US20220275379A9 - Plasmid addiction system to drive desired gene expression - Google Patents

Abstract

The present invention relates to a Plasmid Addiction System for the stabilization of expression plasmids encoding proteins of interest. The invention uses a succinate cycle optimization to ensure the expression of plasmid(s) of interest. By ensuring that plasmids of interest contain genes necessary in the succinate cycle, the system ensures that the passage of the plasmid to daughters and therefore improves the efficiency of production and expression of genes and/or products of interest.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims priority to U.S. Provisional Patent Applications No. 62/697531, filed Jul. 13, 2018, entitled PLASMID ADDICTION SYSTEM TO DRIVE DESIRED GENE EXPRESSION; and No.:62/535596, filed Jul. 21, 2017, entitled PLASMID ADDICTION SYSTEM TO DRIVE DESIRED GENE EXPRESSION, the disclosures of both of which are hereby incorporated by reference in their entirety.
FIELD OF THE INVENTION
• The field of the invention relates to methods and processes useful in maintaining extrachromosomal elements of interest in a microbial production strain using genes from the succinate pathway to ensure inclusion and expression of the elements in daughter cells. More specifically, it relates to the use of a plasmid addiction system that ensures that modified microbial cells will maintain plasmids carrying genes involved in producing desired expression products.
BACKGROUND OF THE INVENTION
• The present invention is directed to a method of manipulating microbial cells in culture to maintain at least one extrachromosomal element of interest containing at least one gene of interest. Typically, this extrachromosomal element is a plasmid, though phages, prophages, phagemids, cosmids, bacterial artificial chromosomes (BACs) also contain extrachromosomal elements to contain transgenes of heterologous interest. Though naturally occurring in bacteria, not all wild type plasmids contain genetic information that is required to maintain the viability of the host cell in normal conditions. However, plasmids can contain genetic information that provides selective advantages to the host under specific environmental challenges such as antibiotic resistance or resistance to noxious compounds present in the environment. However, in those situations where adverse environmental conditions are not present, the presence of the plasmid is, in fact, a metabolic burden upon the cell (Nordstrom and Austin, 1989). In other words, the metabolic activity required to maintain plasmids exerts a small but real metabolic cost to the host cell relative to those cells not carrying the plasmid in question. This metabolic burden is why many daughter cells tend to ‘lose’ the plasmid of interest over time if they can continue to exist or reproduce without it. This process of loss or limited replication of the extrachromosomal element(s) also leads to diminished efficiency in those experiments that require the presence of a plasmid genetic component to produce a product of interest and therefore cultures with significant amounts of daughter cells that do not have the plasmid(s) of interest provide a reduced efficiency for the experiment being conducted. This is particularly acute in those fermentation experiments that rely upon economies of scale and consistent production of a molecule of interest to make their cost targets. Daughter cells deficient in the desired plasmids or extrachromosomal elements represent a media and energy sink in overall production and contribute to the economic benefits of fermentation costs.
• In the biotechnology industry, plasmids and similar extrachromosomal elements have become very important tools in the genetic engineering of microbes and in the expression of proteins of interest and commercial synthetic biology. Such elements can be manipulated and designed to force the host cell to carry them forward or perish. (Balbas 2001; Baba 2006). In this sense, the cells become irreversibly ‘addicted’ to maintaining the extrachromosomal element in the cell despite the consequent metabolic burden (hence the term, Plasmid Addiction System or “PAS”). With such a system in hand the researcher can then focus on driving the host cell culture not just to maintain and express the PAS system genes, but to express all the genes contained on such an extrachromosomal element. According to the current invention, this can entail the expression of a number of genes and potential gene products of interest in microbial systems.
Plasmid Addiction Systems and Alternatives
• Given the power of such techniques to drive the expression of proteins of interest, it is not surprising that a variety of approaches have been developed to ensure the stable maintenance of plasmids in cells (Nordstrom and Austin, 1989). This includes: (i) site-specific recombination systems functioning as plasmid maintenance systems for high-copy plasmid systems (Grindley et al., 2006); (ii) active partition systems (Funnell and Slavcev, 2004); and, as mentioned above, (iii) plasmid addiction systems (PAS), like the invention provided herein, that prevent the continuing survival/replication of cells not containing and expressing the genes of the plasmid of interest (Gerdes et al., 2005).
Site-Specific Recombination Control Systems
• Site-specific recombination is a type of genetic recombination in which a DNA strand exchange takes place between segments possessing at least a certain degree of sequence homology. In this system, a site-specific recombinase(s) (SSRs) performs rearrangements of DNA segments by recognizing and binding to short DNA sequences (sites), at which they cleave the DNA backbone, exchange the two DNA helices involved and then rejoin the DNA strands. (Datsenko and Wanner, 2000). While in some site-specific recombination systems just a single recombinase enzyme and the corresponding recombination sites is enough to perform all these reactions, in other systems a number of accessory proteins and/or accessory sites are also needed—each addition adding to the complexity and thereby decreasing both the reliability and versatility of this system. (Baba et al., 2006). In addition, the constitutive expression of the required recombinases can also lead to undesired genotypic changes and the use of the system in terms of its initial development can be challenging in terms of the transfer of the recombinases genes to progeny.
Plasmid Instability
• As mentioned above, microbes tend towards eliminating plasmids or limiting the reproduction of plasmids in cells due to the ongoing metabolic burden of both maintaining the plasmid itself and of expressing the gene(s) contained therein. (Rosano et al., 2014). Additionally, cells may not favor plasmid replication and expression when the plasmids in question may contain genes, that when expressed, produce toxic products in the cell or in its immediate environment of the cell. Of course, the interest to those utilizing such microbial systems is the maintenance of the engineered genetic changes and consequent expression of the inserted genes. In this sense, stable inheritance of the plasmid and host generally requires that: (1) the plasmid must replicate once each generation; (2) copy number deviations must be rapidly corrected before cell division; and, (3) upon cell division, the products of plasmid replication must be distributed to both daughter cells in a reliable and consistent manner. (Balbas et al., 1986).
• In general, the stable maintenance of low-copy-number plasmids in bacteria is actively driven by partition mechanisms that are responsible for the positioning of plasmids inside the cell prior to replication. Various such partition systems are ubiquitous in the microbial world and are encoded by many bacterial chromosomes as well as plasmids. These systems, although different in sequence and mechanism, typically consist of two proteins and a DNA partition site or prokaryotic centromere on the plasmid in question. One protein binds to the centromere to form a partition complex, and the other protein uses the energy of nucleotide binding and hydrolysis to transport the plasmid as needed. For plasmids, this minimal cassette is sufficient to conduct appropriate segregation. In an optimal setting the strain selected to carry a plasmid of interest will have a partition system that provides or consistent and reliable plasmid reproduction. (Balbas et al., 1986; Rawlings 1999).
Engineered Plasmid Stabilization Systems
• There are systems engineered to stably maintain the plasmids of interest. One particularly common system is the use of antibiotics as selection tools. In such systems, the antibiotic resistance gene in the plasmid of interest protects the cell carrying it, at the same time it effectively “forces” the cell to maintain it when the bacterial cell is grown in a media-enriched with the corresponding antibiotic. (Cranenburgh, R. M. et al., 2001). However, this method is subject to a number of difficulties and concerns. The antibiotic resistance approach is expensive, requiring the use of costly antibiotics and some may find it objectionable as a culture method in when used in industrial production methods could be a way that accelerates and/or spreads the development of bacterial antibiotic resistance that could affect human and/or animal populations negatively. Moreover, in large-scale production applications, the use of antibiotics may impose other limitations. With respect to commercial bioreactors, antibiotic resistance mechanisms can degrade the antibiotic itself and permit a substantial population of plasmid-less cells to persist in the culture. Such plasmid-less cells are unproductive and decrease the overall output of the bioreactor, thereby increasing cost and decreasing efficiency. (Balbas 2001; Baba 2006).
Segregational Plasmid Maintenance Functions
• Stable lower copy number plasmids typically employ a partitioning function that actively distributes plasmid copies between daughter cells. Examples of partitioning mechanisms include: pSC101, F factor, P1 prophage, and IncFII drug resistance plasmids. Such functions act to physically segregate plasmids during replication. In terms of functionality many small plasmids rely on a high copy number, distributed throughout the cell, to ensure at least one copy is maintained by each daughter cell upon division. Many large, low-copy number plasmids, on the other hand, encode active segregation systems to avoid stochastic loss. A variety of partitioning systems exist, but most rely on three components: a centromeric DNA region, a cytomotive filament, and an adaptor protein linking the two. In type II segregation bacterial actin-like protein (ALP) filaments drive plasmid separation. (Balbas et al., 2001; Balbas 1986; Schumacher 2014).
Post-Segregational Killing (PSK) Functions
• Naturally occurring PSK plasmid maintenance functions typically employ a two-component toxin-antitoxin system and generally operate as follows: The plasmid encodes both a toxin and an antitoxin. The antitoxins are less stable than the toxins, which tend to be quite stable. In a plasmid-less daughter cell, the toxins and anti-toxins are no longer being produced; however, the less stable antitoxins quickly degrade, thereby freeing the toxin to kill the cells in the surrounding area without the antitoxins being present. (Gerdes 1990).
• The toxins are generally small proteins and the antitoxins are either small proteins or antisense RNAs which bind to the toxin-encoding mRNAs preventing their synthesis (EX: antisense systems such as hok-sok). In antisense maintenance systems, the antitoxins are antisense RNAs that inhibit translation of toxin-encoding mRNAs. Like the antitoxin peptides, the antisense RNAs are less stable than the toxin-encoding mRNA. Loss of the plasmid permits existing antitoxins to degrade, thereby permitting synthesis of the toxin which kills the host cell. A limitation of the hok-sok system is that a significant number of plasmid-less cells can arise when the hok-sok system is inactivated by mutations within the Hok open reading frame. (Gerdes 1990).
Balanced Lethal Systems
• In a balanced-lethal system (a PSK function), a chromosomal gene encoding an essential structural protein or enzyme is deleted from the bacterial chromosome or is mutated such that the gene can no longer operate (Fu., 2000). The removed or damaged gene is then replaced by a plasmid comprising a fully operating gene. Loss of the plasmid results in an insufficiency of the essential protein and the death of the plasmid-less cell. Balanced-lethal systems based on catalytic enzyme production are subject to a number of deficiencies. In particular, since complementation of the chromosomal gene deletion requires only a single gene copy, it is inherently difficult to maintain more than a few copies of an expression plasmid. The plasmid less host strain must be grown on special media to chemically complement the existing metabolic deficiency. (Fu 2000).
Commercial Efforts & Need
• Biotechnical production processes often operate with plasmid-based expression systems in well-established prokaryotic and eukaryotic hosts such as Escherichia coli or Saccharomyces cerevisiae, respectively. Genetically engineered organisms produce important chemicals, biopolymers, biofuels and high-value proteins like insulin. In those bioprocesses plasmids in recombinant hosts have an essential impact on productivity. (Kroll J., 2010). Plasmid-free cells lead to losses in the entire product recovery and decrease the profitability of the whole process (Table 1). Often, the use of antibiotics in industrial fermentations is not an available or desirable option to maintain plasmid stability. Especially in pharmaceutical or GMP-based fermentation processes, deployed antibiotics must be inactivated and removed. As stated above, they are also costly. Several plasmid addiction systems (PAS) have been described in the literature and referenced above. The current PAS provides a new method that is antibiotic free, remains absolutely necessary for cellular replication and homestasis and allows multiple gene carrying plasmids, or the like, to be maintained efficiently in culture.
• Given the above, there remains a need in the art for a new PAS that is reliant on a balanced lethal system, not requiring antibiotics is useful to industry and can drive the production of high volumes of compounds of interest in a commercially efficient way.
SUMMARY OF THE INVENTION
• The present invention encompasses improved methods of devising a plasmid addiction system that can enhance the production of proteins of interest and do so at commercial scale.
• According to the current invention, a biosynthetic method is provided for the production of one or more proteins of interest in a microbial system.
• Recombinant plasmids carrying the gene of interest are obtained by cultivation of bacteria. For selecting bacterial transformants, and in order to ensure the maintenance of the plasmids in the bacterial host cell, an antibiotic resistance gene is traditionally included in the plasmid backbone. Selection for plasmids is achieved by growing the cells in a medium containing the respective antibiotic, in which only plasmid bearing cells are able to grow, often with a marker gene included. A number of plasmid addiction systems (PAS) already exist, mainly as toxin-antitoxin systems that limit the plasmids to single copy or aimed for use in open environments like bioremediation contexts. However, there are few examples of nutrition-based plasmid addiction systems, or ones exhibiting long-term stability in an industrial setting. The current invention provides both.
• According to the current invention a plasmid addiction system utilizing the succinate pathway as the conditional mutant where key chromosomal genes have been removed and placed in the plasmids to be expressed and maintained in daughter cells. Such a system could be used for the production of specific amylases, pathway genes, lipases, proteases, vitamins or antibiotics, and according to the current invention could be forced to maintain up to four different plasmids.
• According to the preferred embodiments of the invention, the applicants provide a plasmid addiction system based on the synthetic lethal deletion of either the double mutant sucAD or the quadruple mutant sucABCD, wherein the native mutations are complemented on one or more plasmids. The plasmid(s) of interest allows for near wild-type growth without supplementation of DAP or any other intermediate and is retained for many generations in the absence of selective markers. It is useful in a laboratory context, as transformants can be grown LB plates without any additional supplementation; the parent strains cannot grow without supplementation with DAP. It is useful in an industrial context wherein neither antibiotics nor their requisite selection marker genes are wanted or desired. Given the inclusion of up to four required genes this means that four plasmids of different compositions can be retained in a fermentation of interest and at low cost. That is, a single plasmid can be maintained with a single gene of interest or up to four different plasmid types, each with one of the four required genes, carrying other genes of interest can be provided in the current system efficiently and with low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIGS. 1A-1B. Show succinate and succinyl-CoA in context of central E. coli metabolism and cell wall biosynthesis (FIGS. 1A and 1B).
• FIGS. 2A-2C. Show the multiple deletions sucAD (FIG. 2B) and sucABCD (FIG. 2C), which are synthetic lethal in the E. coli chromosome. The genomic context for the native E. coli strain of the invention—BW25113 and its succinyl-CoA operon is shown in FIG. 2A; FIG. 2B provides a schematic of the genomic context of E. coli BW25113 ΔsucAD; and FIG. 2C provides a schematic of the genomic context of E. coli BW25113 ΔsucABCD.
• FIGS. 3A-3E. Show plasmid maps of pDvS and pDvQ plasmids, cloning vectors designed to express sucAB and sucABCD complements rather than antibiotic resistance markers. pDvK-sucAD (FIG. 3A); pDvK-sucABCD (FIG. 3B); pDvS-Kan-dropout (FIG. 3C); and pDvQ-Kan-dropout (FIG. 3D); pDvK-sucBC (FIG. 3E)
• FIGS. 4A-4B. Show succinate pathway knockout mutants, such as BW25113 ΔsucAD (FIG. 4A) and BW25113 ΔsucABCD (FIG. 4B), cannot grow on rich fermentation media.
• FIG. 5. Growth curves of relevant cells on nonselective media. Shows differences between complementation of double- or quadruple knockouts
• FIGS. 6A-6B. Plasmid maps of succinate addiction vectors engineered to express GFP. dvp-a8-skb-sfgfp (FIG. 6A); and pDvQ-GFP (FIG. 6B).
• FIG. 7. Shows the production levels of GFP according to the transformed cellular system of the invention.
DETAILED DESCRIPTION OF THE INVENTION
• The following abbreviations have designated meanings in the specification:
Explanation of Terms:
• Cellular system is any cells that provide for the expression of ectopic proteins. It included bacteria, yeast, plant cells and animal cells. It includes both prokaryotic and eukaryotic cells. It also includes the in vitro expression of proteins based on cellular components, such as ribosomes.
• Growing the Cellular System. Growing includes providing an appropriate medium that would allow cells to multiply and divide given the changes to the succinate pathway. It also includes providing resources so that cells or cellular components can translate and make recombinant proteins. According to the current invention the cells grow on LB media. Such cells do not unless they are supplied with 120 μM DAP.
• Protein Expression. Protein production can occur after requisite gene expression. It consists of the stages after DNA has been transcribed to messenger RNA (mRNA). The mRNA is then translated into polypeptide chains, which are ultimately folded into proteins. DNA is present in the cells through transfection—a process of deliberately introducing nucleic acids into cells. The term is often used for non-viral methods in eukaryotic cells. It may also refer to other methods and cell types, although other terms are preferred: “transformation” is more often used to describe non-viral DNA transfer in bacteria, non-animal eukaryotic cells, including plant cells. In animal cells, transfection is the preferred term as transformation is also used to refer to progression to a cancerous state (carcinogenesis) in these cells. Transduction is often used to describe virus-mediated DNA transfer. Transformation, transduction, and viral infection are included under the definition of transfection for this application.
• Acronyms:
• • TCA—Tricarboxylic Acid
  • DAP—Diaminopimelic Acid
  • PAS—Plasmid addiction system
  • TB—Terrific Broth
  • LB—Luria Broth
  • Y(E)PD—Yeast Extract Peptone Dextrose (medium)
  • sucA—E. coli gene encoding the E1 component of the 2-oxoglutarate dehydrogenase enzyme
  • sucB—E. coli gene encoding the E2 component of the 2-oxoglutarate dehydrogenase enzyme
  • sucC—E. coli gene encoding the β subunit of the succinyl-CoA synthetase enzyme
  • sucD—E. coli gene encoding the α subunit of the succinyl-CoA synthetase enzyme
Alternative Marker Genes
• If marker genes are required for one or more genes of the current invention examples include: genes encoding restriction nucleases (e.g. CviAII, a restriction endonuclease originating from Chlorella virus PBCV-1; Zhang et al., 1992), EcoRI (Tones et al., 2000), genes encoding toxins that interact with proteins, e.g. streptavidin or stv13 (a truncated, easy soluble streptavidin variant), as described by Szafransky et al., 1997; Kaplan et al., 1999; Sano et al., 1995, which act by deprivation of biotin, an essential protein in cell growth); genes encoding proteins that damage membranes (the E gene protein of φX174 (Ronchel et al., 1998; Haidinger et al., 2002), gef (Jensen et al., 1993; Klemm et al., 1995), relF (Knudsen et al., 1995); genes that encode other bacterial toxins, e.g. the ccdb gene (Bernard and Couturier, 1992) that encodes a potent cell killing protein from the F-plasmid trapping the DNA gyrase or sacB from Bacillus subtilis (Gay et al., 1983); or genes that encode eukaryotic toxins that are toxic to the bacterial host (e.g. FUS; Crozat et al., 1993). When using toxic genes, it is essential that their expression can be modulated by an inducible promoter. This promoter must not be active without an inductor, but provide expression upon induction, sufficient to inhibit cell growth.
• In certain embodiments, the marker gene is selected from genes encoding restriction nucleases, streptavidin or genes that have an indirect toxic effect, e.g. sacB, as described above.
• A repressor is a protein that binds to an operator located within the promoter of an operon, thereby down-regulation transcription of the gene(s) located within said operon. Examples for repressors suitable in the present invention are the tetracycline repressor (tet) protein TetR, which regulates transcription of a family of tetracycline resistance determinants in Gram-negative bacteria and binds to tetracycline (Williams, et al., 1998; Beck, et al., 1982; Postle et al., 1984), the tryptophan repressor (trp), which binds to the operator of the trp operon, which contains the tryptophan biosynthesis gene (Yanofski et al., 1987).
• Examples for inducible promoters are promoters, where transcription starts upon addition of a substance, thus being regulatable by the environment, e.g. the lac promoter, which is inducible by IPTG (Jacob and Monod, 1961), the arabinose-promoter (pBAD), inducible by arabinose (Guzman et al., 1995), copper-inducible promoters (Rouch and Brown, 1997), and cumate-inducible promoters (Choi et al 2010).
• Alternately, constitutive promoters may be used, wherein transcription of the desired transgene is always driven on, regardless of the growth phase or environmental variables.
• In an alternative embodiment, one could monitor the expression of a single gene of interest through the use of a marker gene as a reporter gene. Genes that could be used to provide this functionality include genes encoding GFP (Green Fluorescent Protein), hSOD (human superoxide dismutase), lacZ (beta-glucosidase), CAT (chloramphenicol acetyltransferase), nptII (neomycin phosphotransferase) or luciferase.
• A reporter gene is useful in cultivation processes whenever information on the presence or absence of a plasmid in a host cell or on plasmid copy number is needed. Such information is particularly useful when fermentation processes are to be optimized with regard to control of plasmid copy number. A reporter gene may also serve as a surrogate of a toxic marker gene and may thus be used in experimental settings that aim at proving the functionality of constructs to be employed for the gene-regulating or silencing and to determine their effect on a toxic marker gene.
• In certain embodiments of the invention, the marker gene may be an endogenous host gene, which may be any gene of interest that is intended to be regulated. In this case, the host cell is engineered such that the sequence encoding the sequence is operably associated with the relevant host gene.
• While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawing and will herein be described in detail. It should be understood, however, that the drawings and detailed description presented herein are not intended to limit the disclosure to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
• Other features and advantages of this invention will become apparent in the following detailed description of preferred embodiments of this invention, taken with reference to the accompanying drawings.
• The present invention relates to a system for an improved production method for proteins of interest in a microbial system that does not require markers, antibiotics and can produce proteins of interest at a high-level.
Bacterial Strains and Growth Conditions
• BW25113 and the deletions for ΔsucA::KanR and ΔsucD::KanR were obtained from the E. coli Genetic Stock Center (CGSC). Cells were typically grown in Luria Broth (LB), but experiments were also performed in TB, YPD, YEPD, Nutrient Broth with corn steep liquor, and other rich media (Miller, 1972). Diaminopimelic acid (Sigma D1377) was used at 120 μM to aid in screening as the ΔsucAD double deletion is synthetic lethal (Mattozzi et al., 2013; Yu et al., 2006).
• Construction of Strains with Chromosomal Mutations
• P1vir transduction (Miller, 1972) was used to create kanamycin-resistant double knockout strains of E. coli BW25113 and screened with 120 μM DAP on LB kanamycin plates. These were screened for deletions of ΔsucA and ΔsucD via colony PCR. This KanR donor strain was also used to create double knockouts of E. coli strains BL21, BL21(DE3), MG1655, MG1655(DE3) ΔlacY, and W3110. Plasmid pCP20 was used to remove the kanamycin resistance markers using its FLP/FRT-based recombinase (Baba et al., 2006; Datsenko and Wanner, 2000). Since sucA and sucD are separated by only 6 kb, Kan sensitive cells exhibiting the quadruple deletion ΔsucABCD were usually isolated after the pCP20 FLP recombinase step (Datsenko and Wanner, 2000).
Construction of Recombinant Plasmids
• Codon-optimized sequences encoding sucA, sucB, sucC, and sucD were synthesized (Quintara Bioworks, Emeryville Calif.). CIDAR E. coli Modular cloning (Iverson et al., 2016), was used to generate versions of sucABCD natural operon and the sucAD synthetic operon. Both versions were based on the E. coli MG1655 native sequence, but with illegal BsaI and BpiI sites replaced in-frame so as not to affect protein sequences. Additional codon optimization was performed to minimize recombination effects. Operons sucABCD and sucAD were identical except that the sequence between the start codon of sucB and the stop codon of sucC were deleted. (Yu et al., 2005).
• According to the current invention, plasmids were transformed into ΔsucAD and ΔsucABCD strains via electroporation and selected on LB plates without any additional supplementation; the parent strains cannot grow without supplementation with DAP. Clones were confirmed by sequence.
Cultivation of Plasmid-Addicted Strains
• Plasmid-bearing E. coli strains were grown in LB without additional supplementation in 24-well plates and in a BioLector flower plates (Funke et al., 2009).
• The present invention can be widely used in state-of-the-art fermentations, both for plasmid DNA production and for producing recombinant proteins.
• Several approaches for fermentation of pDNA have been described that are useful for applying the present invention. The methods for plasmid DNA production differ with regard to the level of control imposed upon the cells and the numerous factors that influence fermentation.
• To obtain higher quantities of plasmids, the cells can be cultivated in controlled fermenters in so-called “batch fermentations”, in which all nutrients are provided at the beginning and in which no nutrients are added during cultivation. (Reinikainen, P., et al; 1988). Cultivations of this type may be carried out with culture media containing so called “complex components” as carbon and nitrogen sources, as described e.g. by O'Kennedy et al., 2003, and Lahijani et al., 1996, and in WO 96/40905, U.S. Pat. No. 5,487,986 and WO 02/064752. Alternatively, synthetic media may be used for pDNA production, e.g. defined culture media that are specifically designed for pDNA production (Wang et al., 2001; WO 02/064752).
• The present invention may also be used in fed batch fermentations of E. coli, in which one or more nutrients are supplied to the culture by feeding, typically by using a feed-back control algorithm by feeding nutrients in order to control a process parameter at a defined set point. Feed-back control is hence directly related to cell activities throughout fermentation. Control parameters which may be used for feed-back control of fermentations include pH value, on line measured cell density or dissolved oxygen tension (DOT). A feed-back algorithm for controlling the dissolved oxygen tension at a defined set point by the feeding rate was described in WO 99/61633.
• Alternatively, the invention may be applied in a process for producing plasmid DNA, in which E. coli cells are first grown in a pre-culture and subsequently fermented in a main culture, the main culture being a fed-batch process comprising a batch phase and a feeding phase. The culture media of the batch phase and the culture medium added during the feeding phase are chemically defined, and the culture medium of the feeding phase contains a growth-limiting substrate and is added at a feeding rate that follows a pre-defined exponential function, thereby controlling the specific growth rate at a pre-defined value.
• When the marker gene is under the control of an inducible promoter, the inducer may be added to the batch at the beginning and/or pulse-wise (both in a batch and in fed-batch cultivations). During the feed phase, the inducer may be added pulse-wise or continuously.
• At the end of the fermentation process, the cells are harvested and the plasmid DNA is isolated and purified according to processes known in the art, e.g. by methods based on anion exchange and gel permeation chromatography, as described in U.S. Pat. No. 5,981,735 or by using two chromatographic steps, i.e. an anion exchange chromatography as the first step and reversed phase chromatography as the second step, as described in U.S. Pat. No. 6,197,553. Another suitable method for manufacturing plasmid DNA is described in WO 03/051483, which uses two different chromatographic steps, combined with a monolithic support.
• In addition to applying the invention for plasmid production, e.g. for production of plasmids for gene therapy applications, it is also useful for recombinant protein production. (Rawlings 1999).
• With regard to recombinant protein production, in principle, any method may be used that has proven useful for expressing a gene of interest in E. coli, in particular from a ColE1 type plasmid (see, for review, e.g. Jonasson et al., 2002; Balbas, 2001). The protein may be obtained intracellularly (completely or partially soluble or as inclusion bodies) or by secretion (into the cell culture medium or the periplasmic space) from batch fermentations or, preferably, fed-batch cultivations, using complex, synthetic or semisynthetic media.
• In plasmid DNA production, usually plasmid DNA for gene therapy applications, the gene of interest is not expressed in the bacterial host cell. In view of its application in mammals, preferably in humans, where it is to be ultimately expressed, the gene of interest is usually operably associated with a eukaryotic promoter. In contrast, for recombinant production of proteins in E. coli, the gene of interest is to be expressed in the host cell therefore under the control of a prokaryotic promoter.
• For recombinant protein production, the two promoters, i.e. the promoter controlling the marker gene and the promoter controlling the gene of interest, may be different or the same, as long as no interference occurs that disturbs expression of either one.
• Advantageously, since their activity is independent of each other concerning time-point and level of transcription, the promoters are differently regulated. Preferably, the promoter controlling the marker gene is active at the start of the fermentation process and produces moderate amounts of mRNA, while the promoter of the gene of interest is rather strong and activated at a chosen time-point during fermentation. If inducible promoters are used for both the gene of interest and the marker gene, they are usually chosen such that they are turned on by different inducers. Alternatively, the marker gene may be under an inducible promoter and the gene of interest under a constitutive promoter, or vice versa. This applies both for methods in which the marker gene construct is integrated in the bacterial host genome and in which the marker gene construct is contained in a plasmid or phage, as described above.
• With regard to induction of the promoter in the various phases of fermentation, the principle described above for plasmid DNA production applies.
• The invention has the great advantage that all replicated plasmids are devoid of antibiotic resistance genes and are therefore, in addition to gene therapy applications, suitable for all applications for which the absence of antibiotic resistance genes is required or desirable, e.g. for the generation of recombinant yeast strains that are intended for human and animal food production or for the generation of recombinant plants.
Expression and Maintenance During Fermentation
• Maintenance of heterologous DNA presents a major challenge in industrial systems. A number of systems already exist, but there are drawbacks to each of them. Integrating genes into the genome can be slow, require extensive screening, and is limited to a single copy per cell. Larger DNA loops like cosmids and bacterial artificial chromosomes (BACs) can be difficult to isolate from chromosomal DNA or cell debris pellets, and again are limited by copy number. Phages can be difficult to keep contained to the cell types of interest. They could become lytic unexpectedly, causing drastic consequences on a factory-scale. Thus, the most common way to introduce and maintain heterologous DNA into E. coli and other bacterial cultures is via plasmid, wherein the gene(s) of interest are maintained on a small loop of DNA containing sequences comprising an origin of replication and, typically, an antibiotic resistance marker. This marker can be problematic: antibiotics in the media can be expensive and can contaminate final small-molecule products with similar chemical properties. As well, the genes encoding these markers pose a biosafety issue: the antibiotics used in fermentation are the same or similar to the ones used in clinical settings. Though laboratory containment is usually good, large-scale use of antibiotic resistance genes could encourage the spread of dangerous resistant bacteria like methicillin-resistant Staphylococcus aureus (MRSA).
• The principle of the invention, i.e. the metabolic context of the succinyl-CoA synthetic lethal deletions is shown in FIG. 1.
• In embodiments of the invention, the following components are useful:
Host Cells
• Since their replication depends on the host machinery, many plasmids are plasmids with a narrow host range. Replication is often limited to E. coli and related bacteria such as Salmonella and Klebsiella (Kues and Stahl, 1989). However, according to the current invention a great variety of functional hosts are available including eukaryotic systems. Other suitable hosts include: cells of the genera Corynebacterium, Bacillus, Pseudomonas, Vibrio, Bulkholderia, and really any other bacterium that can stably maintain a heterologous plasmid and has a peptidoglycan cell wall.
• Preferred genetic features of the host cell are mutations that improve plasmid stability and quality or recovery of intact recombinant protein. Examples of desirable genetic deletions are:
• • sucA—E. coli gene encoding the E1 component of the 2-oxoglutarate dehydrogenase enzyme
  • sucB—E. coli gene encoding the E2 component of the 2-oxoglutarate dehydrogenase enzyme
  • sucC—E. coli gene encoding the β subunit of the succinyl-CoA synthetase enzyme
  • sucD—E. coli gene encoding the α subunit of the succinyl-CoA synthetase enzyme.
• Each of the genes in this operon encodes part of a heterodimeric enzyme within the TCA cycle. Since sucAB and sucCD are synthetic lethal (Yu et al 2006), either sucAB OR sucCD pair may be deleted and still allow cell growth; albeit with reduced growth rates due to the inability of the cells to use oxygen as a terminal electron acceptor. This can eventually cause cell death, a reduced growth rate, low maximum cell density, and inefficient usage of carbon source. Deletion of at least three of the genes within the sucABCD cluster (or two from opposite conjugate pairs, e.g. ΔsucAD) creates a cell that is auxotrophic for succinyl-CoA. Because succinyl-CoA itself is unstable and expensive to procure commercially, it was discovered that supplementation of DAP in the medium can allow the cells to grow. This is because the external DAP can be incorporated into the cell walls, negating the need for the succinyl-CoA cofactor (FIG. 1). The cells can still grow, but albeit with a growth defect due to their inability to fully utilize oxygen as a terminal electron acceptor.
Constructs for Engineering the Host Cells
• The principle of a construct suitable for engineering the host cells is shown in FIG. 2: The host strains were generated via P1 transduction (above), and the plasmids were produced via Gibson assembly, cloning, Golden Gate and/or modular cloning.
Characteristics of Plasmids for the System
• The plasmids are required to express the genes specifically deleted in the host strain. In this example, codon-optimized versions of E. coli sucAD and sucABCD are expressed on plasmids, complementing the deletions made to BW25113 ΔsucAD and ΔsucABCD respectively.
EXAMPLES
• Two or four key genes expressing essential proteins for the tricarboxylic acid (TCA) cycle were deleted from the E. coli genome. Previously these genes have been shown to be synthetic lethal (Yu et al., 2006). These cells are thus auxotrophic for succinyl-CoA. The cells can make up the energetic needs of the TCA cycle simply through fermentative growth, but the lack of a complete TCA cycle causes inefficient growth, and accumulation of toxic fermentative byproducts ethanol and acetate because the cells are unable to effectively use oxygen as a terminal electron acceptor. This can eventually cause cell death, a reduced growth rate, low maximum cell density, and inefficient usage of carbon source. In addition to the TCA cycle, succinyl-CoA is also used as a cofactor in many metabolic pathways. Perhaps the most important is the lysine synthesis pathway, wherein succinyl-CoA is required as an essential cofactor for generating diaminopimelic acid (DAP). DAP is a key monomer in the murein or peptidoglycan cell wall and was thus required for growth.
• Previously, we built a system taking advantage of this fact (Mattozzi et al., 2013), as a test of a carbon fixation system. However, the knockouts were only used as a proxy for cell metabolic processes from Chloroflexus aurantiacus, not the ability of the cells to retain the plasmid or drive the production of proteins of interest. Double mutant ΔsucAD cells containing a plasmid expressing a succinyl-CoA:(S)-malyl-CoA transferase operon reduced but did not entirely remove the need for DAP in the system.
Bacterial Strains and Growth Conditions
• BW25113 and the deletions for ΔsucA::KanR and ΔsucD::KanR were obtained from the E. coli Genetic Stock Center (CGSC) at Yale University. Cells were typically grown in Luria Broth (LB), but experiments were also performed in TB, YPD, YEPD, Nutrient Broth with corn steep liquor, and other rich media (Miller, 1972). Diaminopimelic acid (Sigma D1377) was used at 120 μM to aid in screening as the ΔsucA(B) Δsuc(C)D double deletion is synthetic lethal (Mattozzi et al., 2013; Yu et al., 2006).
• Construction of Strains with Chromosomal Mutations
• P1vir transduction (Miller, 1972) was used to create kanamycin-resistant double knockout strains of E. coli BW25113 and screened with 120 μM DAP on LB kanamycin plates. These were screened for deletions of ΔsucA and ΔsucD via colony PCR. This KanR donor strain was also used to create double knockouts of E. coli strains BL21, BL21(DE3), BL21*(DE3), MG1655, MG1655(DE3) ΔlacY, C41, and W3110. Plasmid pCP20 was used to remove the kanamycin resistance markers using its FLP/FRT-based recombinase (Baba et al., 2006; Datsenko and Wanner, 2000). Since sucA and sucD are separated by only 6 kb, Kan sensitive cells exhibiting the quadruple deletion ΔsucABCD were usually isolated after the pCP20 FLP recombinase step (Datsenko and Wanner, 2000).
Construction of Recombinant Plasmids
• CIDAR E. coli Modular cloning (Iverson et al., 2016), a Golden Gate based technology, was used to generate versions of sucABCD natural operon and the sucAD synthetic operon. Both versions were based on the E. coli MG1655 native sequence, but with illegal BsaI and BpiI sites replaced in-frame so as not to affect protein sequences. Operons sucABCD and sucAD were identical except that the sequence between the start codon of sucB and the stop codon of sucC were deleted. Plasmids were transformed into sucAD and sucABCD strains via electroporation and selected on LB plates without any additional supplementation; the parent strains cannot grow without supplementation with DAP. Clones were confirmed by sequence.
• Plasmids were transformed into ΔsucAD and ΔsucABCD strains via electroporation and selected on LB plates without any additional supplementation; the parent strains cannot grow without supplementation with DAP. Clones were confirmed by sequence.
• In FIG. 1A, we see the general metabolic context of succinyl-CoA, diaminopimelic acid, and peptidoglycan on murein cell walls. Succinyl-CoA generated by the gene products of sucAB and sucCD is used to produce lysine and its immediate biochemical precursor, diaminopimelate (DAP), critically required for E. coli cell wall (peptidoglycan or murein) biosynthesis. FIG. 1B provides the detailed metabolic context of the succinyl-CoA cofactor in diaminopimelate and lysine metabolism (Excerpted from Michel and Schomberg 2012). In FIG. 2A, the genomic context for the native E. coli strain of the invention—BW25113 and its succinyl-CoA operon are provided. According to the current invention the DNA sequence for this is (SEQ ID NO: 1).
• FIG. 2B provides a schematic of the genomic context of E. coli BW25113 ΔsucAD. This is the result of a P1 transduction in the E. coli genome wherein ΔsucA::kanR was used as a donor. Recipient strain was E. coli BW25113 ΔsucD::kanS, generated by removing kanamycin resistance via pCP20-mediated FRT excision (thereby providing SEQ ID NO: 2). FIG. 2C provides a schematic of the genomic context of E. coli BW25113 ΔsucABCD. The result is the removal of kanamycin resistance via pCP20-mediated FRT excision. Since sucA and sucD are within 6 kb, deletions of the entire sucABCD operon were isolated in the purification process (SEQ ID NO: 3).
• In FIG. 3A, a map of plasmid pDvK-SucAD, according to the current invention is provided. It was used to test for plasmid retention in nonselective media, as hosted in ΔsucAD cells. In this case, the plasmid retains kanamycin resistance markers for later testing. Although promoters, RBS, and terminators are specifically enumerated here, the experiments have shown effectively no difference in expression upon varying these (SEQ ID NO: 4). In FIG. 3B, we provide a map of plasmid pDvK-SucABCD, used to test for plasmid retention in nonselective media, as hosted in ΔsucABCD cells. According to the current invention, the plasmid retains kanamycin resistance markers for later testing. Although promoters, RBS, and terminators are specifically enumerated here, the experiments have shown effectively no difference in expression upon varying these (SEQ ID NO: 5). In FIG. 3C, we see the plasmid map of pDvS-Kan of the invention, wherein the kanamycin resistance marker is easily removed by the gene of interest, and the genes sucAD can instead be used as a selection marker. Although promoters, RBS, and terminators are specifically enumerated here, the experiments have shown effectively no difference in expression upon varying these (SEQ ID NO: 6). In FIG. 3E, a map of plasmid pDvK-SucBC, according to the current invention is provided. It was used to test for plasmid retention in nonselective media, as hosted in ΔsucABCD cells in combination with pDvK-SucAD. In this case, the plasmid retains kanamycin resistance markers for later testing. Although promoters, RBS, and terminators are specifically enumerated here, the experiments have shown effectively no difference in expression upon varying these sequences (SEQ ID NO: 10).
• In FIG. 4A, applicants show the succinate pathway knockout mutant BW25113 ΔsucAD cannot grow on rich fermentation media Luria Broth. However, supplanting the media with diaminopimelic acid (DAP) allows for an increase in growth rate, correlating to the concentration of DAP provided. According to the current invention, the plasmid map of pDvQ-Kan is provided in FIG. 3D, wherein the kanamycin resistance marker is easily removed by the gene of interest, and the genes sucABCD can instead be used as a selection marker. Although promoters, RBS, and terminators are specifically enumerated here, the experiments have shown effectively no difference in expression upon varying these (SEQ ID NO: 7). In FIG. 4B, applicants demonstrate that the succinate pathway knockout mutant BW25113 ΔsucABCD cannot grow on rich fermentation media Luria Broth. However, supplanting the media with diaminopimelic acid (DAP) allows for an increase in growth rate, correlating to the concentration of DAP provided.
• In FIG. 5, we provide the rescue of growth phenotypes with plasmid-borne sucA(BC)D in artificial operons. Deletions of sucAD and sucABCD from E. coli BW25113 do not grow at all on rich fermentation media Luria Broth. However, supplying the cells with plasmids pDvK-SucAD and pDvK-SucABCD, respectively, allows the cells to reach densities of close to that of wild-type BW25113. In FIG. 6A, the plasmid map of pDvS-GFP contains a sequence encoding the green fluorescent protein cloned into the pDvS vector, wherein the kanamycin resistance marker is easily removed by the gene of interest. (SEQ ID NO: 8) is provided. In FIG. 6B, a plasmid map of pDvQ-GFP containing a sequence encoding the green fluorescent protein cloned into the pDvQ vector (SEQ ID NO: 9) is provided. In FIG. 7, we see the production levels of green fluorescent protein (GFP), normalized by cell density according to the transformed cellular system of the invention. The cells containing the deletions and corresponding complements (open symbols, solid lines) exhibit more GFP per unit cell density than those with wild-type backgrounds (filled symbols, dotted lines), or those without plasmids (open symbols, dashed lines). In Table 1 we see that over time in the absence of kanamycin selection, the cells lacking the deletions lose kanamycin resistance (borne on the plasmids) within a few days, whereas the deletion mutants retain their resistance and their plasmids over the entire course of the study.
• In addition, in Table 1, Applicants demonstrate that the Fraction of colony forming units (cfu) that retains a KanR plasmid over days. E. coli BW25113 was transformed with three Kan resistant plasmids (pDvK-sucAD, pDvK-sucABCD, and pDvK, rows A-D). E. coli BW25113 deletions in sucAD and sucABCD were also transformed with complement plasmids (pDvK-sucAD, pDvK-sucABCD, respectively, rows E-F). 50-mL cultures were grown in LB without kanamycin as selective pressure. Aliquots of cells were plated on kanamycin and non-selective plates and cfu calculated daily. The fraction of KanR cfu over total cfu is reported.
• Over time in the absence of kanamycin selection, the cells lacking the deletions lose kanamycin resistance (borne on the plasmids) within a few days, whereas the deletion mutants retain their resistance and their plasmids over the entire course of the study.

• TABLE 1
  Table of growth characteristics for the retention of a single plasmid in the system. Fraction of cfu that retain kanamycin
  sensitivity (and thus maintain the plasmid expressing succinate pathway and kanamycin resistance genes) over time.

  Day

  Strain

  Plasmid

  	1	2	3	4	5	6	7	8

  BW25113		0	0	0	0	0	0	0	0
  BW25113		0	0	0	0	0	0	0	0
  ΔsucAD
  BW25113
  		0	0	0	0	0	0	0	0
  ΔsucABCD
  BW25113	pDvK-sucAD	<1.0	1.35 ± 0.53	0.75 ± 0.17	0.48 ± 0.03	0.09 ± 0.03	0.08 ± 0.08	~0	~0
  BW25113	pDvK-sucABCD	<1.0	<1.0	0.04 ± 0.06	0.04 ± 0.00	0.16 ± 0.05	~0	~0	~0
  BW25113	pDvK	<1.0	0.96 ± 0.12	0.63 ± 0.17	0.55 ± 0.19	0.44 ± 0.15	0.50 ± 0.37	0.08 ± 0.07	0.12 ± 0.15
  BW25113	pDvK-sucAD	0.99 ± 0.23	1.93 ± 0.12	0.84 ± 0.17	1.05 ± 0.42	1.06 ± 0.04	1.30 ± 0.61	1.15 ± 0.30	1.11 ± 0.19
  ΔsucAD
  BW25113	pDvK-sucABCD	0.86 ± 0.02	0.99 ± 0.27	0.98 ± 0.17	1.26 ± 0.44	1.02 ± 0.02	0.94 ± 0.21	1.23 ± 0.24	1.19 ± 0.01
  ΔsucABCD

Maintenance of Multiple Plasmids in the System
• A similar experiment was performed to test the maintenance of multiple plasmids in the system. Cells of BW25113 ΔsucABCD should not be able to grow in LB without supplementation of DAP, unless at least two of the genes sucAB and sucCD are expressed on plasmids. Plasmids pDVK-sucAD and pDVK-sucBC, were constructed. Neither of these plasmids has a sufficient set of genes to allow growth of BW25113 ΔsucABCD without DAP supplementation, but they will in combination. Without supplementation with DAP, the cells retained their kanamycin resistance, and thus their ability to maintain both plasmids (Tables 2, 3).

• TABLE 2
  Retention of Two-Plasmids. Fraction of cfu that retain kanamycin
  sensitivity (and thus maintain the plasmids expressing succinate
  pathway and kanamycin resistance genes) over time).

  Strain	Plasmid(s)	Day 1
  BW25113	pDVK	0.49 ± 0.27
  BW25113 ΔsucABCD	pDVK-sucBC and pDVP-sucAD	0.69 ± 0.37

• Retention of both plasmids utilized according to the current invention is shown in patch plates, wherein colonies of each strain/plasmid combination were struck on LB agar plates of different media conditions. Only with a complimentary and/or complete set of genes sucAB sucCD can E. coli BW25113 ΔsucABCD grow without DAP supplementation. Kanamycin resistance shows maintenance of the plasmids, here two, as KanR is linked to the succinate operon genes.

• TABLE 3
  Retention of Two-Plasmids. Patch growth of plasmids on different
  media. Cultures of each strain/plasmid were grown in LB + DAP overnight and diluted to
  OD600 = 1.0. Ten μL of this dilution (and serial 50-fold dilutions) were plated onto the media
  conditions in each column. − = no growth. + = growth patch observed with OD600 = 1.0 cells. ++ =
  growth patch observed from 50-fold serial dilution (OD600 = 0.02). +++ = growth patch
  observed from 2500-fold serial dilution (OD600 = 0.0004). ++++ = growth patch observed from
  125,000-fold serial dilution (OD600 = 0.000008).

  Strain	Plasmid(s)	LB	LB + Kan	LB + DAP	LB + Kan50 + DAP
  BW25113		++++	−	++++	−
  BW25113 ΔsucABCD		−	−	++++	−
  BW25113 ΔsucABCD	pDVK-sucAD	+	−	++++	++++
  BW25113 ΔsucABCD	pDVK-sucBC	−	−	++++	++++
  BW25113 ΔsucABCD	pDVK-sucAD and pDVK-	+++	+++	++++	+++
  	sucBC

Cultivation of Plasmid-Addicted Strains
• Plasmid-bearing E. coli strains were grown in LB without additional supplementation in 24-well plates and in a BioLector flower plates (Funke et al., 2009).
• To achieve tight regulation of toxic gene expression, a tightly regulable promoter like the arabinose-inducible PBAD promoter (Guzman et al., 1995) is preferably used, in particular in the case that the marker protein is per se toxic to the cells.
• Another way to control expression of the marker gene is by using constitutive promoters in combination with a gene that is non-toxic (e.g. a reporter gene) or only toxic under defined conditions, e.g. the Bacillus subtilis sacB gene, which is only toxic to E. coli when sucrose is present.
• The promoter is chosen in coordination with the effect of the marker gene product and the required efficiency of down-regulation or silencing effect. For example, for a construct containing a non-toxic or less toxic marker gene, a stronger promoter is desirable.
Additional Embodiments
• As is evident from the foregoing description, certain aspects of the present disclosure are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. It is accordingly intended that the claims shall cover all such modifications and applications that do not depart from the spirit and scope of the present disclosure.
• Moreover, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. Although any methods and materials equivalent to or those described herein can be used in the practice or testing of the present disclosure, the preferred methods and materials are described above.
• Although the foregoing invention has been described in some detail by way of illustration and example for purposes of understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced. Therefore, the description and examples should not be construed as limiting the scope of the invention, which is delineated by the appended claims.
• Accordingly, it is to be understood that the embodiments of the invention herein providing for the production of specific molecules are merely illustrative of the application of the principles of the invention. It will be evident from the foregoing description that changes in the form, methods of use, and applications of the elements of the disclosed production methods and selected microbial strains may be resorted to without departing from the spirit of the invention, or the scope of the appended claims.
STATEMENT OF INDUSTRIAL APPLICABILITY/TECHNICAL FIELD
• This disclosure has applicability in the commercial production of food ingredients, fragrances, medicines and pharmaceuticals. This disclosure relates generally to a method for enhanced and more precisely controlled biosynthetic production of desired end products via selected microbial strains.
LITERATURE CITED AND INCORPORATED BY REFERENCE
• Baba, T., et al., Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection, MOL. SYST. BIOL. 2, 2006.
• Balbas, P., et al; Understanding the Art of Producing Protein and Nonprotein Molecules in Escherichia coli; MOLECULAR BIOTECHNOLOGY (2001) vol. 19, (3) pp. 251-67.
• Balbas, P. et al; Plasmid vector pBR322 and its special purpose derivatives—a review; GENE (1986) vol. 50 pp. 3-40.
• Beck, C. F. et al; A Multifunctional Gene (tetR) Controls Tn10-encoded Tetracycline Resistance; JOURNAL OF BACTERIOLOGY (1982) vol. 150 No. 2 pp. 633-42.
• Brantl, S., Antisense RNAs in plasmids: control of replication and maintenance, Academic Press, PLASMID 48 (2002) pp. 165-173.
• Brosius, J., et al; Construction and Fine Mapping of Recombinant Plasmids Containing the rrnB Ribosomal RNA Operon of E. coli; PLASMID (1981) vol. 6 No. 1 pp. 112-18.
• Chang, A. C. Y., et al., Construction and Characterization of Amplifiable Multicopy DNA Cloning Vehicles Derived for the P15A Cryptic Miniplasmid; J. BACTERIOLOGY (1978) vol. 134 No. 3 pp. 1141-56.
• Choi Y. J., et al; Novel, Versatile, and Tightly Regulated Expression System for Escherichia coli Strains. APPLIED AND E NVIRONMENTAL MICROBIOLOGY (2010) vol 76, No. 15, pp. 5058-66.
• Cranenburgh, R. M. et al., Escherichia coli strains that allow antibiotic free plasmid selection and maintenance by repressor titration, NUCLEIC ACIDS RESEARCH, 2001 vol. 29, No. 5, 1-6.
• Datsenko, K. A., and Wanner, B. L., One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products, PROC. NATL. ACAD. SCI. U. S. A. 97, 6640-5. (2000)
• Deboy, R. T., et al; Target Site Selection by Tn7: attTn7 Transcription and Target Activity; JOURNAL OF BACTERIOLOGY (2000) vol. 182 No. 11 pp. 3310-3313.
• Del Solar, Gloria et al., Replication and Control of Circular Bacterial Plasmids, MICROBIOLOLOGY AND MOLECULAR BIOLOGY REVIEWS (1998) vol. 62, No. 2, pp. 434-64.
• Eguchi, Yutaka., et al., Complexes Formed by Complementary RNA Stem-loops. Their Formation, Structure and Interaction with ColE1 Rom Protein, JOURNAL MOLECULAR BIOLOGY (1991) vol. 220 pp. 831-842.
• Fu X., et al., Development of a Chromosome-Plasmid Balanced Lethal System of Lactobacillus Acidophilus with thyA Gene as Selective Marker, MICROBIOL. IMMUNOL., 44(7) p551-56 (2000).
• Funke, M. et al., The baffled microtiter plate: Increased oxygen transfer and improved online monitoring in small scale fermentations, BIOTECHNOL. BIOENG. (2009) 103, 1118-28.
• Furste, J. P., et al., Molecular Cloning of the Plasmid RP4 Primase Region in a Multi-Host-Range tacP Expression Vector, GENE (1986) vol. 48 pp. 119-131.
• Gerdes K., et al., Mechanism of post-segregational killing by the hok/sok system of plasmid R1: sok antisense RNA regulates formation of a hok mRNA species correlated with killing of plasmid-free cells, MOL. MICROBIOL. (1990) 4(11): 1807-18.
• Gerdes, S. Y., et al., Experimental Determination and System Level Analysis of Essential Genes in Escherichia coli MG1655, JOURNAL OF BACTERIOLOGY (2003) vol. 185 No. 19 pp. 5673-5684.
• Haegg, P., et al., A Host/Plasmid System that is not Dependent on Antibiotics and Antibiotic Genes for Stable Plasmid Maintenance in Eschericia coli., JOURNAL OF BIO TECHNOLOGY (2004) vol. 111 pp. 17-30.
• Helinski, D. R., et al; Replication Control and Other Stable Maintenance Mechanisms of Plasmids (1996) American Society for Microbiology Press, Washington, DC, pp. 2295-2324.
• Hiszczynska-Sawicka, Elzbieta., et al., Effect of Integration Host Factor on RNA II Synthesis in Replication of Plasmid Containing orip15A, PLASMID (1998) vol. 40 pp. 150-157.
• Herring, Christopher D., et al., Conditional Lethal Amber Mutations in Essential Escherichia coli Genes, JOURNAL OF BACTERIOLOGY (2004) vol. 186, No. 9 pp. 2673-2681.
• Jensen, L. Bogo., et al., A Substrate-Dependent Biological Containment System for Pseudonomas Putida Based on the Escherichia coli gef Gene, APPLIED AND ENVIRONMENTAL MICROBIOLOGY (1993) vol. 59, No. 11 pp. 3713-3717.
• Knudsen, Steen., et al., Development and Testing of Improved Suicide Functions for Biological Containment of Bacteria, APPLIED AND ENVIRONMENTAL MICROBIOLOGY (1995) vol. 61, No. 3 pp. 985-991.
• Kroll, J., et al., Plasmid Addiction Systems: Perspectives and Applications in Biotechnology, MICROB. BIOTECHNOL., 3(6) pp 634-57 (2010).
• Kues, U., et al., Replication of Plasmids in Gram-Negative Bacteria, MICROBIOLOGICAL REVIEWS (1989) vol. 53, No. 4 pp. 491-516.
• Mairhofer, Jurgen et al.; A novel antibotic free plasmid selection system: Advances in safe and efficient DNA therapy, BIOTECHNOLOGY JOURNAL (2008) 3, pp. 83-89.
• Mattozzi, M. D. et al., Expression of the sub pathways of the Chloroflexus aurantiacus 3-hydroxypropionate carbon fixation bicycle in E. coli: Toward horizontal transfer of autotrophic growth, METAB. ENG. 16, 130-139. (2013).
• Merlin, S., et al., Assessment of Quantitative Models for Plasmid ColE1 Copy Number Control, J. MOL. BIOL. (1995) vol. 248 pp. 211-19.
• Michel, Gerhard and Dietmar Schomberg; METABOLIC PATHWAYS. (2012) John Wiley and Sons, New York
• O'Kennedy, R. D., et al., Effects of Fermentation Strategy on the Characteristics of Plasmid DNA Production, BIOTECHNOLOGY APPL. B IOCHEM. (2003) vol. 37 pp. 83-90.
• O'Kennedy, R. D., et al., Effects of Growth Medium Selection on Plasmid DNA Production and Initial Processing Steps, JOURNAL OF BIOTECHNOLOGY (2000) vol. 76 pp. 175-183.
• Postle, K., et al; Nucleotide Sequence of the Repressor Gene of the TN10 Tetracycline Resistance Determinant; NUCLEIC ACIDS RESEARCH (1984) vol. 12, No. 12 pp. 4849-4863.
• Pfaffenzeller, I., Using ColE1-derived RNA I for suppression of a bacterially encoded gene: implication for a novel plasmid addiction system, BIOTECH. J. (2006), pp. 1-7.
• Rawlings, D. E.; Protein Toxin-Antitoxin, Bacterial Plasmid Addiction Systems and their evolution with Special reference to the pas System of pTF-FC2; FEMS Microbiology Letters (1999) vol. 176 pp. 269-77.
• Reinikainen, P., et al; Escherichia coli Plasmid Production in Fermenter; BIOTECHNOLOGY BIOENGINERING (1988) vol. 33 pp. 386-93.
• Ronchel, M. Carmen., et al; Characterization of Cell Lysis in Pseudomonas putida induced Upon Expression of Heterologous Killing Genes, APPLIED AND ENVIRONMENTAL MICROBIOLOGY, (1998) vol. 64, No. 12 pp. 4904-11.
• Germán L. Rosano and Eduardo A. Ceccarelli, Recombinant protein expression in Escherichia coli: advances and challenges, MICROBIOL. (2014); 5:172.
• Schumacher M. A., Bacterial plasmid partition machinery: a minimalist approach to survival, CURR OPIN STRUCT BIOL., (2012) Feb;22(1):72-9
• Tomizawa, Jun-Ichi., et al; Plasmid ColE1 Incompatibility Determined by Interaction of RNA I with Primer Transcript; PROC. NATL. ACAD. SCI. USA (1981) vol. 78, No. 10 pp. 6096-6100.
• Tomizawa, Jun-Ichi, Control of ColE1 Plasmid replication: The Process of Binding of RNA I to the Primer Transcript, CELL (1984) vol. 38 pp. 861-870.
• Tomizawa, Jun-Ichi; Control of ColE1 Plasmid Replication: Binding of RNA I to RNA II and Inhibition of Primer Formation, CELL (1986) vol. 47 pp. 89-97.
• Torres, B., et al., As Gene Containment Strategy Based on a Restriction Modification System, ENVIRONMENTAL MICROBIOLOGY (2000) vol. 2, No. 5 pp. 555-63.
• Vieira, J., et al; The pUC Plasmids, an M13mp7-Derived System for Insertion Mutagenesis and Sequencing with Synthetic Universal Primers; GENE (1982) vol. 19 pp. 259-68.
• Williams, S. G., et al., Repressor Titration: A Novel System for Selection and Stable Maintenance of Recombinant Plasmids, NUCLEIC ACIDS RESEARCH (1998) vol. 26, No. 9 pp. 2120-24.
• Yu., B. J., et al., sucAB and sucCD are mutually essential genes in Escherichia coli., FEMS MICROBIOL. LETT. (2005) 254, 245-50.
• Yu, D., et al; An Efficient Recombination System for Chromosome Engineering in Escherichia coli; PNAS (2000) vol. 97, No. 11 pp. 5978-83.

• Sequences of Interest:

  SEQ ID NO: 1 SE operon and genomic context sequence

  ccggtcaggcactgactgtgaatgagaaaggcgaagatgtggttgttccgggactgtttgccgttggtgaaatcgct

  tgtgtatcggtacacggcgctaaccgtctgggcggcaactcgctgctggacctggtggtctttggtcgcgcggcagg

  tctgcatctgcaagagtctatcgccgagcagggcgcactgcgcgatgccagcgagtctgatgttgaagcgtctctgg

  atcgcctgaaccgctggaacaataatcgtaacggtgaagatccggtggcgatccgtaaagcgctgcaagaatgtatg

  cagcataacttctcggtcttccgtgaaggtgatgcgatggcgaaagggcttgagcagttgaaagtgatccgcgagcg

  tctgaaaaatgcccgtctggatgacacttccagcgagttcaacacccagcgcgttgagtgcctggaactggataacc

  tgatggaaacggcgtatgcaacggctgtttctgccaacttccgtaccgaaagccgtggcgcgcatagccgcttcgac

  ttcccggatcgtgatgatgaaaactggctgtgccactccctgtatctgccagagtcggaatccatgacgcgccgaag

  cgtcaacatggaaccgaaactgcgcccggcattcccgccgaagattcgtacttactaatgcggagacaggaaaatga

  gactcgagttttcaatttatcgctataacccggatgttgatgatgctccgcgtatgcaggattacaccctggaagcg

  gatgaaggtcgcgacatgatgctgctggatgcgcttatccagctaaaagagaaagatcccagcctgtcgttccgccg

  ctcctgccgtgaaggtgtgtgcggttccgacggtctgaacatgaacggcaagaatggtctggcctgtattaccccga

  tttcggcactcaaccagccgggcaagaagattgtgattcgcccgctgccaggtttaccggtgatccgcgatttggtg

  gtagacatgggacaattctatgcgcaatatgagaaaattaagccttacctgttgaataatggacaaaatccgccagc

  tcgcgagcatttacagatgccagagcagcgcgaaaaactcgacgggctgtatgaatgtattctctgcgcatgttgtt

  caacctcttgtccgtctttctggtggaatcccgataagtttatcggcccggcaggcttgttagcggcatatcgtttc

  ctgattgatagccgtgataccgagactgacagccgcctcgacggtttgagtgatgcattcagcgtattccgctgtca

  cagcatcatgaactgcgtcagtgtatgtccgaaggggctgaacccgacgcgcgccatcggccatatcaagtcgatgt

  tgttgcaacgtaatgcgtaaaccgtaggcctgataagacgcgcaagcgtcgcatcaggcaaccagtgccggatgcgg

  cgtgaacgccttatccggcctacaagtcattacccgtaggcctgataagcgcagcgcatcaggcgtaacaaagaaat

  gcaggaaatctttaaaaactgcccctgacactaagacagtttttaaaggttccttcgcgagccactacgtagacaag

  agctcgcaagtgaaccccggcacgcacatcactgtgcgtggtagtatccacggcgaagtaagcataaaaaagatgct

  taagggatcacgatgcagaacagcgctttgaaagcctggttggactcttcttacctctctggcgcaaaccagagctg

  gatagaacagctctatgaagacttcttaaccgatcctgactcggttgacgctaactggcgttcgacgttccagcagt

  tacctggtacgggagtcaaaccggatcaattccactctcaaacgcgtgaatatttccgccgcctggcgaaagacgct

  tcacgttactcttcaacgatctccgaccctgacaccaatgtgaagcaggttaaagtcctgcagctcattaacgcata

  ccgcttccgtggtcaccagcatgcgaatctcgatccgctgggactgtggcagcaagataaagtggccgatctggatc

  cgtctttccacgatctgaccgaagcagacttccaggagaccttcaacgtcggttcatttgccagcggcaaagaaacc

  atgaaactcggcgagctgctggaagccctcaagcaaacctactgcggcccgattggtgccgagtatatgcacattac

  cagcaccgaagaaaaacgctggatccaacagcgtatcgagtctggtcgcgcgactttcaatagcgaagagaaaaaac

  gcttcttaagcgaactgaccgccgctgaaggtcttgaacgttacctcggcgcaaaattccctggcgcaaaacgcttc

  tcgctggaaggcggtgacgcgttaatcccgatgcttaaagagatgatccgccacgctggcaacagcggcacccgcga

  agtggttctcgggatggcgcaccgtggtcgtctgaacgtgctggtgaacgtgctgggtaaaaaaccgcaagacttgt

  tcgacgagttcgccggtaaacataaagaacacctcggcacgggtgacgtgaaataccacatgggcttctcgtctgac

  ttccagaccgatggcggcctggtgcacctggcgctggcgtttaacccgtctcaccttgagattgtaagcccggtagt

  tatcggttctgttcgtgcccgtctggacagacttgatgagccgagcagcaacaaagtgctgccaatcaccatccacg

  gtgacgccgcagtgaccgggcagggcgtggttcaggaaaccctgaacatgtcgaaagcgcgtggttatgaagttggc

  ggtacggtacgtatcgttatcaacaaccaggttggtttcaccacctctaatccgctggatgcccgttctacgccgta

  ctgtactgatatcggtaagatggttcaggccccgattttccacgttaacgcggacgatccggaagccgttgcctttg

  tgacccgtctggcgctcgatttccgtaacacctttaaacgtgatgtcttcatcgacctggtgtgctaccgccgtcac

  ggccacaacgaagccgacgagccgagcgcaacccagccgctgatgtatcagaaaatcaaaaaacatccgacaccgcg

  caaaatctacgctgacaagctggagcaggaaaaagtggcgacgctggaagatgccaccgagatggttaacctgtacc

  gcgatgcgctggatgctggcgattgcgtagtggcagagtggcgtccgatgaacatgcactctttcacctggtcgccg

  tacctcaaccacgaatgggacgaagagtacccgaacaaagttgagatgaagcgcctgcaggagctggcgaaacgcat

  cagcacggtgccggaagcagttgaaatgcagtctcgcgttgccaagatttatggcgatcgccaggcgatggctgccg

  gtgagaaactgttcgactggggcggtgcggaaaacctcgcttacgccacgctggttgatgaaggcattccggttcgc

  ctgtcgggtgaagactccggtcgcggtaccttcttccaccgccacgcggtgatccacaaccagtctaacggttccac

  ttacacgccgctgcaacatatccataacgggcagggcgcgttccgtgtctgggactccgtactgtctgaagaagcag

  tgctggcgtttgaatatggttatgccaccgcagaaccacgcactctgaccatctgggaagcgcagttcggtgacttc

  gccaacggtgcgcaggtggttatcgaccagttcatctcctctggcgaacagaaatggggccggatgtgtggtctggt

  gatgttgctgccgcacggttacgaagggcaggggccggagcactcctccgcgcgtctggaacgttatctgcaacttt

  gtgctgagcaaaacatgcaggtttgcgtaccgtctaccccggcacaggtttaccacatgctgcgtcgtcaggcgctg

  cgcgggatgcgtcgtccgctggtcgtgatgtcgccgaaatccctgctgcgtcatccgctggcggtttccagcctcga

  agaactggcgaacggcaccttcctgccagccatcggtgaaatcgacgagcttgatccgaagggcgtgaagcgcgtag

  tgatgtgttctggtaaggtttattacgacctgctggaacagcgtcgtaagaacaatcaacacgatgtcgccattgtg

  cgtatcgagcaactctacccgttcccgcataaagcgatgcaggaagtgttgcagcagtttgctcacgtcaaggattt

  tgtctggtgccaggaagagccgctcaaccagggcgcatggtactgcagccagcatcatttccgtgaagtgattccgt

  ttggggcttctctgcgttatgcaggccgcccggcctccgcctctccggcggtagggtatatgtccgttcaccagaaa

  cagcaacaagatctggttaatgacgcgctgaacgtcgaataaataaaggatacacaatgagtagcgtagatattctg

  gtccctgacctgcctgaatccgtagccgatgccaccgtcgcaacctggcataaaaaacccggcgacgcagtcgtacg

  tgatgaagtgctggtagaaatcgaaactgacaaagtggtactggaagtaccggcatcagcagacggcattctggatg

  cggttctggaagatgaaggtacaacggtaacgtctcgtcagatccttggtcgcctgcgtgaaggcaacagcgccggt

  aaagaaaccagcgccaaatctgaagagaaagcgtccactccggcgcaacgccagcaggcgtctctggaagagcaaaa

  caacgatgcgttaagcccggcgatccgtcgcctgctggctgaacacaatctcgacgccagcgccattaaaggcaccg

  gtgtgggtggtcgtctgactcgtgaagatgtggaaaaacatctggcgaaagccccggcgaaagagtctgctccggca

  gcggctgctccggcggcgcaaccggctctggctgcacgtagtgaaaaacgtgtcccgatgactcgcctgcgtaagcg

  tgtggcagagcgtctgctggaagcgaaaaactccaccgccatgctgaccacgttcaacgaagtcaacatgaagccga

  ttatggatctgcgtaagcagtacggtgaagcgtttgaaaaacgccacggcatccgtctgggctttatgtccttctac

  gtgaaagcggtggttgaagccctgaaacgttacccggaagtgaacgcttctatcgacggcgatgacgtggtttacca

  caactatttcgacgtcagcatggcggtttctacgccgcgcggcctggtgacgccggttctgcgtgatgtcgataccc

  tcggcatggcagacatcgagaagaaaatcaaagagctggcagtcaaaggccgtgacggcaagctgaccgttgaagat

  ctgaccggtggtaacttcaccatcaccaacggtggtgtgttcggttccctgatgtctacgccgatcatcaacccgcc

  gcagagcgcaattctgggtatgcacgctatcaaagatcgtccgatggcggtgaatggtcaggttgagatcctgccga

  tgatgtacctggcgctgtcctacgatcaccgtctgatcgatggtcgcgaatccgtgggcttcctggtaacgatcaaa

  gagttgctggaagatccgacgcgtctgctgctggacgtgtagtagtttaagtttcacctgcactgtagaccggataa

  ggcattatcgccttctccggcaattgaagcctgatgcgacgctgacgcgtcttatcaggcctacgggaccaccaatg

  taggtcggataaggcgcaagcgccgcatccgacaagcgatgcctgatgtgacgtttaacgtgtcttatcaggcctac

  gggtgaccgacaatgcccggaagcgatacgaaatattcGGTCTACGGTTTAAAAGATAACGATTACTGAAGGATGGA

  CAGAACACatgaacttacatgaatatcaggcaaaacaactttttgcccgctatggcttaccagcaccggtgggttat

  gcctgtactactccgcgcgaagcagaagaagccgcttcaaaaatcggtgccggtccgtgggtagtgaaatgtcaggt

  tcacgctggtggccgcggtaaagcgggcggtgtgaaagttgtaaacagcaaagaagacatccgtgcttttgcagaaa

  actggctgggcaagcgtctggtaacgtatcaaacagatgccaatggccaaccggttaaccagattctggttgaagca

  gcgaccgatatcgctaaagagctgtatctcggtgccgttgttgaccgtagttcccgtcgtgtggtctttatggcctc

  caccgaaggcggcgtggaaatcgaaaaagtggcggaagaaactccgcacctgatccataaagttgcgcttgatccgc

  tgactggcccgatgccgtatcagggacgcgagctggcgttcaaactgggtctggaaggtaaactggttcagcagttc

  accaaaatcttcatgggcctggcgaccattttcctggagcgcgacctggcgttgatcgaaatcaacccgctggtcat

  caccaaacagggcgatctgatttgcctcgacggcaaactgggcgctgacggcaacgcactgttccgccagcctgatc

  tgcgcgaaatgcgtgaccagtcgcaggaagatccgcgtgaagcacaggctgcacagtgggaactgaactacgttgcg

  ctggacggtaacatcggttgtatggttaacggcgcaggtctggcgatgggtacgatggacatcgttaaactgcacgg

  cggcgaaccggctaacttccttgacgttggcggcggcgcaaccaaagaacgtgtaaccgaagcgttcaaaatcatcc

  tctctgacgacaaagtgaaagccgttctggttaacatcttcggcggtatcgttcgttgcgacctgatcgctgacggt

  atcatcggcgcggtagcagaagtgggtgttaacgtaccggtcgtggtacgtctggaaggtaacaacgccgaactcgg

  cgcgaagaaactggctgacagcggcctgaatattattgcagcaaaaggtctgacggatgcagctcagcaggttgttg

  ccgcagtggaggggaaataatgtccattttaatcgataaaaacaccaaggttatctgccagggctttaccggtagcc

  aggggactttccactcagaacaggccattgcatacggcactaaaatggttggcggcgtaaccccaggtaaaggcggc

  accacccacctcggcctgccggtgttcaacaccgtgcgtgaagccgttgctgccactggcgctaccgcttctgttat

  ctacgtaccagcaccgttctgcaaagactccattctggaagccatcgacgcaggcatcaaactgattatcaccatca

  ctgaaggcatcccgacgctggatatgctgaccgtgaaagtgaagctggatgaagcaggcgttcgtatgatcggcccg

  aactgcccaggcgttatcactccgggtgaatgcaaaatcggtatccagcctggtcacattcacaaaccgggtaaagt

  gggtatcgtttcccgttccggtacactgacctatgaagcggttaaacagaccacggattacggtttcggtcagtcga

  cctgtgtcggtatcggcggtgacccgatcccgggctctaactttatcgacattctcgaaatgttcgaaaaagatccg

  cagaccgaagcgatcgtgatgatcggtgagatcggcggtagcgctgaagaagaagcagctgcgtacatcaaagagca

  cgttaccaagccagttgtgggttacatcgctggtgtgactgcgccgaaaggcaaacgtatgggccacgcgggtgcca

  tcattgccggtgggaaagggactgcggatgagaaattcgctgctctggaagccgcaggcgtgaaaaccgttcgcagc

  ctggcggatatcggtgaagcactgaaaactgttctgaaataaatatctgtaataagaaatagccctcgccgcttccc

  tctacaggaatggcgaagggctgtcggtttcgacatggttggccatcgtatgatggccttttttgtgcttatcgcga

  tgattttcgctgcgctatcagggtaaatttatagtcatcggtattaaaagcgttgcggctatattcaaacacccgac

  catcaactaaatatccacgcgatactttttcaagaatcggctttgtctggctgatattaagcagacggctcatctct

  tcggttggcatcagaggaatgatttcctgttcgctacgatcgataaccattttcttcacttcttcgataaagtgata

  tttcgaattttccatgacctgccaggtgagatccgggaacaacgcaagcggcatccaggtttcttccagcgccattg

  gcttttgcttgcgatagcgcacgcgcttcacatgccacacacgatcctgcggggtgatttgtagctgttgctgaaga

  aaatcgtcagccggaatcacttcgaatatcagaacttcactgtgtgtatcgacgtgacggtccgacagtttttcatc

  aaaactggttaactgaaaaatatcgtaattgacccgctcttctttgacgtaagtcccgctgccctgaatgctttcga

  ggatctgctgctcgactagctggcgcaaagcctgacgcaccgtaacccggctgacgccaaactctgtttgtagcgct

  gattcagtgggtaacgcatcgccaggtttaagctcgccacgcgcaatttgttcacgaatgcgatcggcaatctgccg

  gtataagggcttgtgtcccatttttagtatctcattaatacgaatttaaccattatgcccgataaattcatcctgta

  aataatacaaatacaatacaaataatttcaatcaagtgaaattgatcacataatggtattgttttatcg

  SEQ ID NO: 2. Sequence of the genomic context of E. coli BW25113 ΔsucAD.

  ccggtcaggcactgactgtgaatgagaaaggcgaagatgtggttgttccgggactgtttgccgttggtgaaatcgct

  tgtgtatcggtacacggcgctaaccgtctgggcggcaactcgctgctggacctggtggtctttggtcgcgcggcagg

  tctgcatctgcaagagtctatcgccgagcagggcgcactgcgcgatgccagcgagtctgatgttgaagcgtctctgg

  atcgcctgaaccgctggaacaataatcgtaacggtgaagatccggtggcgatccgtaaagcgctgcaagaatgtatg

  cagcataacttctcggtcttccgtgaaggtgatgcgatggcgaaagggcttgagcagttgaaagtgatccgcgagcg

  tctgaaaaatgcccgtctggatgacacttccagcgagttcaacacccagcgcgttgagtgcctggaactggataacc

  tgatggaaacggcgtatgcaacggctgtttctgccaacttccgtaccgaaagccgtggcgcgcatagccgcttcgac

  ttcccggatcgtgatgatgaaaactggctgtgccactccctgtatctgccagagtcggaatccatgacgcgccgaag

  cgtcaacatggaaccgaaactgcgcccggcattcccgccgaagattcgtacttactaatgcggagacaggaaaatga

  gactcgagttttcaatttatcgctataacccggatgttgatgatgctccgcgtatgcaggattacaccctggaagcg

  gatgaaggtcgcgacatgatgctgctggatgcgcttatccagctaaaagagaaagatcccagcctgtcgttccgccg

  ctcctgccgtgaaggtgtgtgcggttccgacggtctgaacatgaacggcaagaatggtctggcctgtattaccccga

  tttcggcactcaaccagccgggcaagaagattgtgattcgcccgctgccaggtttaccggtgatccgcgatttggtg

  gtagacatgggacaattctatgcgcaatatgagaaaattaagccttacctgttgaataatggacaaaatccgccagc

  tcgcgagcatttacagatgccagagcagcgcgaaaaactcgacgggctgtatgaatgtattctctgcgcatgttgtt

  caacctcttgtccgtctttctggtggaatcccgataagtttatcggcccggcaggcttgttagcggcatatcgtttc

  ctgattgatagccgtgataccgagactgacagccgcctcgacggtttgagtgatgcattcagcgtattccgctgtca

  cagcatcatgaactgcgtcagtgtatgtccgaaggggctgaacccgacgcgcgccatcggccatatcaagtcgatgt

  tgttgcaacgtaatgcgtaaaccgtaggcctgataagacgcgcaagcgtcgcatcaggcaaccagtgccggatgcgg

  cgtgaacgccttatccggcctacaagtcattacccgtaggcctgataagcgcagcgcatcaggcgtaacaaagaaat

  gcaggaaatctttaaaaactgcccctgacactaagacagtttttaaaggttccttcgcgagccactacgtagacaag

  agctcgcaagtgaaccccggcacgcacatcactgtgcgtggtagtatccacggcgaagtaagcataaaaaagatgct

  taagggatcacgagtgtaggctggagctgcttcgaagttcctatactttctagagaataggaacttcggaataggaa

  cttcaagatccccttattagaagaactcgtcaagaaggcgatagaaggcgatgcgctgcgaatcgggagcggcgata

  ccgtaaagcacgaggaagcggtcagcccattcgccgccaagctcttcagcaatatcacgggtagccaacgctatgtc

  ctgatagcggtccgccacacccagccggccacagtcgatgaatccagaaaagcggccattttccaccatgatattcg

  gcaagcaggcatcgccatgggtcacgacgagatcctcgccgtcgggcatgcgcgccttgagcctggcgaacagttcg

  gctggcgcgagcccctgatgctcttcgtccagatcatcctgatcgacaagaccggcttccatccgagtacgtgctcg

  ctcgatgcgatgtttcgcttggtggtcgaatgggcaggtagccggatcaagcgtatgcagccgccgcattgcatcag

  ccatgatggatactttctcggcaggagcaaggtgagatgacaggagatcctgccccggcacttcgcccaatagcagc

  cagtcccttcccgcttcagtgacaacgtcgagcacagctgcgcaaggaacgcccgtcgtggccagccacgatagccg

  cgctgcctcgtcctgcagttcattcagggcaccggacaggtcggtcttgacaaaaagaaccgggcgcccctgcgctg

  acagccggaacacggcggcatcagagcagccgattgtctgttgtgcccagtcatagccgaatagcctctccacccaa

  gcggccggagaacctgcgtgcaatccatcttgttcaatcatgcgaaacgatcctcatcctgtctcttgatcagatct

  tgatcccctgcgccatcagatccttggcggcaagaaagccatccagtttactttgcagggcttcccaaccttaccag

  agggcgccccagctggcaattccggttcgcttgctgtccataaaaccgcccagtctagctatcgccatgtaagccca

  ctgcaagctacctgctttctctttgcgcttgcgttttcccttgtccagatagcccagtagctgacattcatccgggg

  tcagcaccgtttctgcggactggctttctacgtgttccgcttcctttagcagcccttgcgccctgagtgcttgcggc

  agcgtgagcttcaaaagcgctctgaagttcctatactttctagagaataggaacttcgaactgcaggtcgacggatc

  cccggaattaattctcatgtttgacagaaaggatacacaatgagtagcgtagatattctggtccctgacctgcctga

  atccgtagccgatgccaccgtcgcaacctggcataaaaaacccggcgacgcagtcgtacgtgatgaagtgctggtag

  aaatcgaaactgacaaagtggtactggaagtaccggcatcagcagacggcattctggatgcggttctggaagatgaa

  ggtacaacggtaacgtctcgtcagatccttggtcgcctgcgtgaaggcaacagcgccggtaaagaaaccagcgccaa

  atctgaagagaaagcgtccactccggcgcaacgccagcaggcgtctctggaagagcaaaacaacgatgcgttaagcc

  cggcgatccgtcgcctgctggctgaacacaatctcgacgccagcgccattaaaggcaccggtgtgggtggtcgtctg

  actcgtgaagatgtggaaaaacatctggcgaaagccccggcgaaagagtctgctccggcagcggctgctccggcggc

  gcaaccggctctggctgcacgtagtgaaaaacgtgtcccgatgactcgcctgcgtaagcgtgtggcagagcgtctgc

  tggaagcgaaaaactccaccgccatgctgaccacgttcaacgaagtcaacatgaagccgattatggatctgcgtaag

  cagtacggtgaagcgtttgaaaaacgccacggcatccgtctgggctttatgtccttctacgtgaaagcggtggttga

  agccctgaaacgttacccggaagtgaacgcttctatcgacggcgatgacgtggtttaccacaactatttcgacgtca

  gcatggcggtttctacgccgcgcggcctggtgacgccggttctgcgtgatgtcgataccctcggcatggcagacatc

  gagaagaaaatcaaagagctggcagtcaaaggccgtgacggcaagctgaccgttgaagatctgaccggtggtaactt

  caccatcaccaacggtggtgtgttcggttccctgatgtctacgccgatcatcaacccgccgcagagcgcaattctgg

  gtatgcacgctatcaaagatcgtccgatggcggtgaatggtcaggttgagatcctgccgatgatgtacctggcgctg

  tcctacgatcaccgtctgatcgatggtcgcgaatccgtgggcttcctggtaacgatcaaagagttgctggaagatcc

  gacgcgtctgctgctggacgtgtagtagtttaagtttcacctgcactgtagaccggataaggcattatcgccttctc

  cggcaattgaagcctgatgcgacgctgacgcgtcttatcaggcctacgggaccaccaatgtaggtcggataaggcgc

  aagcgccgcatccgacaagcgatgcctgatgtgacgtttaacgtgtcttatcaggcctacgggtgaccgacaatgcc

  cggaagcgatacgaaatattcggtctacggtttaaaagataacgattactgaaggatggacagaacacatgaactta

  catgaatatcaggcaaaacaactttttgcccgctatggcttaccagcaccggtgggttatgcctgtactactccgcg

  cgaagcagaagaagccgcttcaaaaatcggtgccggtccgtgggtagtgaaatgtcaggttcacgctggtggccgcg

  gtaaagcgggcggtgtgaaagttgtaaacagcaaagaagacatccgtgcttttgcagaaaactggctgggcaagcgt

  ctggtaacgtatcaaacagatgccaatggccaaccggttaaccagattctggttgaagcagcgaccgatatcgctaa

  agagctgtatctcggtgccgttgttgaccgtagttcccgtcgtgtggtctttatggcctccaccgaaggcggcgtgg

  aaatcgaaaaagtggcggaagaaactccgcacctgatccataaagttgcgcttgatccgctgactggcccgatgccg

  tatcagggacgcgagctggcgttcaaactgggtctggaaggtaaactggttcagcagttcaccaaaatcttcatggg

  cctggcgaccattttcctggagcgcgacctggcgttgatcgaaatcaacccgctggtcatcaccaaacagggcgatc

  tgatttgcctcgacggcaaactgggcgctgacggcaacgcactgttccgccagcctgatctgcgcgaaatgcgtgac

  cagtcgcaggaagatccgcgtgaagcacaggctgcacagtgggaactgaactacgttgcgctggacggtaacatcgg

  ttgtatggttaacggcgcaggtctggcgatgggtacgatggacatcgttaaactgcacggcggcgaaccggctaact

  tccttgacgttggcggcggcgcaaccaaagaacgtgtaaccgaagcgttcaaaatcatcctctctgacgacaaagtg

  aaagccgttctggttaacatcttcggcggtatcgttcgttgcgacctgatcgctgacggtatcatcggcgcggtagc

  agaagtgggtgttaacgtaccggtcgtggtacgtctggaaggtaacaacgccgaactcggcgcgaagaaactggctg

  acagcggcctgaatattattgcagcaaaaggtctgacggatgcagctcagcaggttgttgccgcagtggaggggaaa

  taatgATTCCGGGGATCCGTCGACCTGCAGTTCGAAGTTCCTATCTAGAAAGTATAGGAACTTCGAAGCAGCTCCAG

  CCTACActgaaaactgttctgaaataaatatctgtaataagaaatagccctcgccgcttccctctacaggaatggcg

  aagggctgtcggtttcgacatggttggccatcgtatgatggccttttttgtgcttatcgcgatgattttcgctgcgc

  tatcagggtaaatttatagtcatcggtattaaaagcgttgcggctatattcaaacacccgaccatcaactaaatatc

  cacgcgatactttttcaagaatcggctttgtctggctgatattaagcagacggctcatctcttcggttggcatcaga

  ggaatgatttcctgttcgctacgatcgataaccattttcttcacttcttcgataaagtgatatttcgaattttccat

  gacctgccaggtgagatccgggaacaacgcaagcggcatccaggtttcttccagcgccattggcttttgcttgcgat

  agcgcacgcgcttcacatgccacacacgatcctgcggggtgatttgtagctgttgctgaagaaaatcgtcagccgga

  atcacttcgaatatcagaacttcactgtgtgtatcgacgtgacggtccgacagtttttcatcaaaactggttaactg

  aaaaatatcgtaattgacccgctcttctttgacgtaagtcccgctgccctgaatgctttcgaggatctgctgctcga

  ctagctggcgcaaagcctgacgcaccgtaacccggctgacgccaaactctgtttgtagcgctgattcagtgggtaac

  gcatcgccaggtttaagctcgccacgcgcaatttgttcacgaatgcgatcggcaatctgccggtataagggcttgtg

  tcccatttttagtatctcattaatacgaatttaaccattatgcccgataaattcatcctgtaaataatacaaataca

  atacaaataatttcaatcaagtgaaattgatcacataatggtattgttttatcg

  SEQ ID NO: 3. Sequence of the genomic context of E. coli BW25113 ΔsucABCD

  ccggtcaggcactgactgtgaatgagaaaggcgaagatgtggttgttccgggactgtttgccgttggtgaaatcgct

  tgtgtatcggtacacggcgctaaccgtctgggcggcaactcgctgctggacctggtggtctttggtcgcgcggcagg

  tctgcatctgcaagagtctatcgccgagcagggcgcactgcgcgatgccagcgagtctgatgttgaagcgtctctgg

  atcgcctgaaccgctggaacaataatcgtaacggtgaagatccggtggcgatccgtaaagcgctgcaagaatgtatg

  cagcataacttctcggtcttccgtgaaggtgatgcgatggcgaaagggcttgagcagttgaaagtgatccgcgagcg

  tctgaaaaatgcccgtctggatgacacttccagcgagttcaacacccagcgcgttgagtgcctggaactggataacc

  tgatggaaacggcgtatgcaacggctgtttctgccaacttccgtaccgaaagccgtggcgcgcatagccgcttcgac

  ttcccggatcgtgatgatgaaaactggctgtgccactccctgtatctgccagagtcggaatccatgacgcgccgaag

  cgtcaacatggaaccgaaactgcgcccggcattcccgccgaagattcgtacttactaatgcggagacaggaaaatga

  gactcgagttttcaatttatcgctataacccggatgttgatgatgctccgcgtatgcaggattacaccctggaagcg

  gatgaaggtcgcgacatgatgctgctggatgcgcttatccagctaaaagagaaagatcccagcctgtcgttccgccg

  ctcctgccgtgaaggtgtgtgcggttccgacggtctgaacatgaacggcaagaatggtctggcctgtattaccccga

  tttcggcactcaaccagccgggcaagaagattgtgattcgcccgctgccaggtttaccggtgatccgcgatttggtg

  gtagacatgggacaattctatgcgcaatatgagaaaattaagccttacctgttgaataatggacaaaatccgccagc

  tcgcgagcatttacagatgccagagcagcgcgaaaaactcgacgggctgtatgaatgtattctctgcgcatgttgtt

  caacctcttgtccgtctttctggtggaatcccgataagtttatcggcccggcaggcttgttagcggcatatcgtttc

  ctgattgatagccgtgataccgagactgacagccgcctcgacggtttgagtgatgcattcagcgtattccgctgtca

  cagcatcatgaactgcgtcagtgtatgtccgaaggggctgaacccgacgcgcgccatcggccatatcaagtcgatgt

  tgttgcaacgtaatgcgtaaaccgtaggcctgataagacgcgcaagcgtcgcatcaggcaaccagtgccggatgcgg

  cgtgaacgccttatccggcctacaagtcattacccgtaggcctgataagcgcagcgcatcaggcgtaacaaagaaat

  gcaggaaatctttaaaaactgcccctgacactaagacagtttttaaaggttccttcgcgagccactacgtagacaag

  agctcgcaagtgaaccccggcacgcacatcactgtgcgtggtagtatccacggcgaagtaagcataaaaaagatgAT

  TCCGGGGATCCGTCGACCTGCAGTTCGAAGTTCCTATCTAGAAAGTATAGGAACTTCGAAGCAGCTCCAGCCTACAc

  tgaaaactgttctgaaataaatatctgtaataagaaatagccctcgccgcttccctctacaggaatggcgaagggct

  gtcggtttcgacatggttggccatcgtatgatggccttttttgtgcttatcgcgatgattttcgctgcgctatcagg

  gtaaatttatagtcatcggtattaaaagcgttgcggctatattcaaacacccgaccatcaactaaatatccacgcga

  tactttttcaagaatcggctttgtctggctgatattaagcagacggctcatctcttcggttggcatcagaggaatga

  tttcctgttcgctacgatcgataaccattttcttcacttcttcgataaagtgatatttcgaattttccatgacctgc

  caggtgagatccgggaacaacgcaagcggcatccaggtttcttccagcgccattggcttttgcttgcgatagcgcac

  gcgcttcacatgccacacacgatcctgcggggtgatttgtagctgttgctgaagaaaatcgtcagccggaatcactt

  cgaatatcagaacttcactgtgtgtatcgacgtgacggtccgacagtttttcatcaaaactggttaactgaaaaata

  tcgtaattgacccgctcttctttgacgtaagtcccgctgccctgaatgctttcgaggatctgctgctcgactagctg

  gcgcaaagcctgacgcaccgtaacccggctgacgccaaactctgtttgtagcgctgattcagtgggtaacgcatcgc

  caggtttaagctcgccacgcgcaatttgttcacgaatgcgatcggcaatctgccggtataagggcttgtgtcccatt

  tttagtatctcattaatacgaatttaaccattatgcccgataaattcatcctgtaaataatacaaatacaatacaaa

  taatttcaatcaagtgaaattgatcacataatggtattgttttatcg

  SEQ ID NO: 4. Sequence of Plasmid pDVK-SucAD, used for testing plasmid retention

  in nonselective media

  ccacccatctgggtttgccggtatttaataccgtgcgtgaggcggttgccgcaaccggtgccacggcttcagttatc

  tatgttcctgccccattttgtaaagattcaattctggaagctattgatgcgggcatcaaattgattattacgattac

  cgaaggtatccctacgctggatatgttgacggttaaagtgaaacttgatgaagcgggggtacgcatgattggtccga

  attgtccgggcgttattactccaggtgagtgcaaaattggtattcagccgggtcatattcacaaacctgggaaagtc

  ggaattgtgtctcgttctggcactctgacgtatgaggcagttaaacagaccacagattatggctttgggcagagtac

  ctgtgtcggcatcggaggcgatcctattccggggagtaattttatcgatattctggaaatgtttgagaaagatccgc

  agaccgaggcaatcgtcatgattggcgagattggcggttccgcggaagaagaagctgcagcctatatcaaagaacat

  gtcacaaaaccggtagtgggctatatcgcgggagtcacggccccaaaaggtaaacgtatgggccatgccggagcgat

  catcgcgggcggcaaaggcactgcagatgaaaaatttgcagcccttgaggccgctggcgtaaaaacggtccgttccc

  ttgctgatattggtgaagcactgaaaaccgtgttgaaataaAGGTccaggcatcaaataaaacgaaaggctcagtcg

  aaagactgggcctttcgttttatctgttgtttgtcggtgaacgctctctactagagtcacactggctcaccttcggg

  tgggcctttctgcgtttatatgccatgtcttctactagtagcggccgctgcagtccggcaaaaaagggcaaggtgtc

  accaccctgccctttttctttaaaaccgaaaagattacttcgcgttatgcaggcttcctcgctcactgactcgctgc

  gctcggtcgttcggctgcggcgagcggtatcagctcactcaaaggcggtaatacggttatccacagaatcaggggat

  aacgcaggaaagaacatgtgagcaaaaggccagcaaaaggccaggaaccgtaaaaaggccgcgttgctggcgttttt

  ccacaggctccgcccccctgacgagcatcacaaaaatcgacgctcaagtcagaggtggcgaaacccgacaggactat

  aaagataccaggcgtttccccctggaagctccctcgtgcgctctcctgttccgaccctgccgcttaccggatacctg

  tccgcctttctcccttcgggaagcgtggcgctttctcatagctcacgctgtaggtatctcagttcggtgtaggtcgt

  tcgctccaagctgggctgtgtgcacgaaccccccgttcagcccgaccgctgcgccttatccggtaactatcgtcttg

  agtccaacccggtaagacacgacttatcgccactggcagcagccactggtaacaggattagcagagcgaggtatgta

  ggcggtgctacagagttcttgaagtggtggcctaactacggctacactagaagaacagtatttggtatctgcgctct

  gctgaagccagttaccttcggaaaaagagttggtagctcttgatccggcaaacaaaccaccgctggtagcggtggtt

  tttttgtttgcaagcagcagattacgcgcagaaaaaaaggatctcaagaagatcctttgatcttttctacggggtct

  gacgctcagtggaacgaaaactcacgttaagggattttggtcatgagattatcaaaaaggatcttcacctagatcct

  tttaaattaaaaatgaagttttaaatcaatctaaagtatatatgagtaaacttggtctgacagctcgagtcccgtca

  agtcagcgtaatgctctgccagtgttacaaccaattaaccaattctgattagaaaaactcatcgagcatcaaatgaa

  actgcaatttattcatatcaggattatcaataccatatttttgaaaaagccgtttctgtaatgaaggagaaaactca

  ccgaggcagttccataggatggcaagatcctggtatcggtctgcgattccgactcgtccaacatcaatacaacctat

  taatttcccctcgtcaaaaataaggttatcaagtgagaaatcaccatgagtgacgactgaatccggtgagaatggca

  aaagcttatgcatttctttccagacttgttcaacaggccagccattacgctcgtcatcaaaatcactcgcatcaacc

  aaaccgttattcattcgtgattgcgcctgagcgagacgaaatacgcgatcgctgttaaaaggacaattacaaacagg

  aatcgaatgcaaccggcgcaggaacactgccagcgcatcaacaatattttcacctgaatcaggatattcttctaata

  cctggaatgctgttttcccggggatcgcagtggtgagtaaccatgcatcatcaggagtacggataaaatgcttgatg

  gtcggaagaggcataaattccgtcagccagtttagtctgaccatctcatctgtaacatcattggcaacgctaccttt

  gccatgtttcagaaacaactctggcgcatcgggcttcccatacaatcgatagattgtcgcacctgattgcccgacat

  tatcgcgagcccatttatacccatataaatcagcatccatgttggaatttaatcgcggcctggagcaagacgtttcc

  cgttgaatatggctcataacaccccttgtattactgtttatgtaagcagacagttttattgttcatgatgatatatt

  tttatcttgtgcaatgtaacatcagagattttgagacacaacgtggctttgttgaataaatcgaacttttgctgagt

  tgaaggatcagctcgagtgccacctgacgtctaagaaaccattattatcatgacattaacctataaaaataggcgta

  tcacgaggcagaatttcagataaaaaaaatccttagctttcgctaaggatgatttctggaattcgcggccgcttcta

  gagactagtggaagacatCGCTttgacagctagctcagtcctaggtactgtgctagcTACTttaaactccccgagca

  atagtaatgcagaactcagcattgaaagcatggcttgatagctcctatttatcaggtgctaaccagagctggattga

  acagctgtatgaagattttctgacagatccggattcagtggatgcgaattggcgcagcacttttcagcagttgcctg

  gcaccggtgtaaaaccggatcagtttcattcccagacgcgggagtattttcgtcgtctggcgaaagatgcgagccgg

  tattcaagtacaatttctgatccggatacgaatgtaaaacaggtgaaagtgcttcagttaattaatgcgtatcgctt

  tagaggccatcagcatgcgaatctggatccgctgggcttatggcagcaggataaagtcgcggatctggatccaagtt

  ttcacgatttaacggaagctgattttcaggaaacctttaacgtcggctcattcgcaagtgggaaagaaacaatgaaa

  ctgggcgaacttcttgaggcgctgaaacagacttattgtggccctattggtgcggaatatatgcatattacctcaac

  tgaagagaaacgttggattcagcagagaatcgagagtggccgcgcgacttttaactccgaagaaaaaaaaagattcc

  tgtcagaactgacagccgcggaaggcttagagcggtatttgggtgccaaattcccaggagcaaaacggttcagcctg

  gagggcggtgatgcgctgatcccgatgctgaaagaaatgattcggcatgcgggaaatagcggaactcgggaagtggt

  gttaggaatggcacaccgcggccgtttgaatgtactggttaacgtattaggaaaaaaacctcaggatttatttgatg

  agttcgcgggaaaacataaagaacatctgggcactggtgatgtcaaatatcacatgggcttctcaagtgattttcag

  acggatggaggtctggttcacctggcactggcatttaatccttctcatctggaaatcgtaagtccggtcgttattgg

  ttccgtgcgcgctcgcttagatcggttagatgaacctagctcaaacaaagttttaccaatcacgatccatggggatg

  cagctgttaccggacagggtgttgtgcaggagactttgaatatgtccaaagcgcgcgggtatgaggtgggtggtacg

  gtgcgtattgttatcaataatcaggtgggttttacaaccagtaaccctctggatgctcgctctacgccgtattgcac

  tgatattggtaaaatggtgcaggcaccaatttttcacgtcaatgccgatgatccggaagctgttgcctttgttacgc

  gcctggctctggattttcgtaacactttcaaacgtgatgtatttatcgatttagtatgctatcgtcgtcatggtcat

  aatgaggctgatgaacctagcgctacccagccactgatgtatcagaaaattaaaaaacatcctacccctcgtaaaat

  ttatgcggataaactggagcaggaaaaagtggctactcttgaagatgctactgaaatggtcaatctttatcgggatg

  cattggatgcgggtgattgcgtggtcgcggaatggcgcccgatgaatatgcattcatttacttggtcaccgtattta

  aatcatgagtgggatgaggaatatccgaataaagtggagatgaaacgcctgcaggaattagcaaaacgtattagcac

  agtacctgaagcggttgagatgcagtctagagttgccaaaatctatggagatcgccaggccatggcagcaggggaaa

  aactttttgattgggggggagccgaaaacctggcatatgcgacgctggtagatgagggcattccggtgcgcctttct

  ggtgaagattctgggcgcggtactttttttcatcggcacgctgttattcataaccagtctaacggtagtacttatac

  tccgctgcagcacatccacaatggtcagggtgcgttccgtgtatgggattccgtgctgagtgaagaagcggttcttg

  cgtttgagtatgggtatgcaactgccgagccacgcacgctgacgatctgggaagcccagtttggcgattttgcaaat

  ggtgcccaggtggtaatcgatcagtttattagctccggcgaacagaaatgggggcggatgtgtggtttagttatgtt

  gttaccgcatggctatgaaggtcagggacctgagcacagctcagcgcgcctggaacgctatcttcagctgtgtgcgg

  aacagaacatgcaggtatgcgttccttccacgccggctcaggtttatcatatgttaagacgtcaggccttgcgcggt

  atgcggcgcccgttggtcgtgatgtccccgaaaagtttactgcgccatccgttagcagttagcagcctggaggaact

  ggcaaacggtacgttcttgccagctatcggcgaaatcgatgaactggatcctaaaggggtgaaacgcgttgttatgt

  gttctggtaaagtgtattatgatcttttggaacagcgtcgcaaaaataatcagcacgatgtagctattgtgcggatc

  gagcagctgtatccgttcccgcacaaagcaatgcaggaagtgctgcagcagttcgcacatgtcaaagattttgtctg

  gtgtcaggaggaaccgcttaatcagggggcctggtattgtagtcagcaccatttccgggaggtgatcccgtttgggg

  cgtccttacggtatgctggtcgccctgcctccgcaagtccggccgtgggatatatgagcgttcaccagaaacagcag

  caggatttggtgaatgatgctttgaatgtggaatgaatgtccatcctgatcgacaaaaacactaaagtaatttgtca

  gggctttaccggttcccagggcacatttcactcagagcaggccatcgcttatgggaccaaaatggtgggtggtgtaa

  cgcctggtaaaggaggca

  SEQ ID NO: 5. Sequence of Plasmid pDVK-SucABCD, used for testing plasmid retention

  in nonselective media

  ccggcgaaagagtctgctccggcagcggctgctccggcggcgcaaccggctctggctgcacgtagtgaaaaacgtgt

  cccgatgactcgcctgcgtaagcgtgtggcagagcgtctgctggaagcgaaaaactccaccgccatgctgaccacgt

  tcaacgaagtcaacatgaagccgattatggatctgcgtaagcagtacggtgaagcgtttgaaaaacgccacggcatc

  cgtctgggctttatgtccttctacgtgaaagcggtggttgaagccctgaaacgttacccggaagtgaacgcttctat

  cgacggcgatgacgtggtttaccacaactatttcgacgtcagcatggcggtttctacgccgcgcggcctggtgacgc

  cggttctgcgtgatgtcgataccctcggcatggcagacatcgagaagaaaatcaaagagctggcagtcaaaggccgt

  gacggcaagctgaccgttgaagatctgaccggtggtaacttcaccatcaccaacggtggtgtgttcggttccctgat

  gtctacgccgatcatcaacccgccgcagagcgcaattctgggtatgcacgctatcaaagatcgtccgatggcggtga

  atggtcaggttgagatcctgccgatgatgtacctggcgctgtcctacgatcaccgtctgatcgatggtcgcgaatcc

  gtgggcttcctggtaacgatcaaagagttgctggaagatccgacgcgtctgctgctggacgtgtagtagtttaagtt

  tcacctgcactgtagaccggataaggcattatcgccttctccggcaattgaagcctgatgcgacgctgacgcgtctt

  atcaggcctacgggaccaccaatgtaggtcggataaggcgcaagcgccgcatccgacaagcgatgcctgatgtgacg

  tttaacgtgtcttatcaggcctacgggtgaccgacaatgcccggaagcgatacgaaatattcGGTCTACGGTTTAAA

  AGATAACGATTACTGAAGGATGGACAGAACACatgaacttacatgaatatcaggcaaaacaactttttgcccgctat

  ggcttaccagcaccggtgggttatgcctgtactactccgcgcgaagcagaagaagccgcttcaaaaatcggtgccgg

  tccgtgggtagtgaaatgtcaggttcacgctggtggccgcggtaaagcgggcggtgtgaaagttgtaaacagcaaaG

  AGgacatccgtgcttttgcagaaaactggctgggcaagcgtctggtaacgtatcaaacagatgccaatggccaaccg

  gttaaccagattctggttgaagcagcgaccgatatcgctaaagagctgtatctcggtgccgttgttgaccgtagttc

  ccgtcgtgtggtctttatggcctccaccgaaggcggcgtggaaatcgaaaaagtggcggaagaaactccgcacctga

  tccataaagttgcgcttgatccgctgactggcccgatgccgtatcagggacgcgagctggcgttcaaactgggtctg

  gaaggtaaactggttcagcagttcaccaaaatcttcatgggcctggcgaccattttcctggagcgcgacctggcgtt

  gatcgaaatcaacccgctggtcatcaccaaacagggcgatctgatttgcctcgacggcaaactgggcgctgacggca

  acgcactgttccgccagcctgatctgcgcgaaatgcgtgaccagtcgcaggaagatccgcgtgaagcacaggctgca

  cagtgggaactgaactacgttgcgctggacggtaacatcggttgtatggttaacggcgcaggtctggcgatgggtac

  gatggacatcgttaaactgcacggcggcgaaccggctaacttccttgacgttggcggcggcgcaaccaaagaacgtg

  taaccgaagcgttcaaaatcatcctctctgacgacaaagtgaaagccgttctggttaacatcttcggcggtatcgtt

  cgttgcgacctgatcgctgacggtatcatcggcgcggtagcagaagtgggtgttaacgtaccggtcgtggtacgtct

  ggaaggtaacaacgccgaactcggcgcgaagaaactggctgacagcggcctgaatattattgcagcaaaaggtctga

  cggatgcagctcagcaggttgttgccgcagtggaggggaaataatgtccattttaatcgataaaaacaccaaggtta

  tctgccagggctttaccggtagccaggggactttccactcagaacaggccattgcatacggcactaaaatggttggc

  ggcgtaaccccaggtaaaggcggcaccacccacctcggcctgccggtgttcaacaccgtgcgtgaagccgttgctgc

  cactggcgctaccgcttctgttatctacgtaccagcaccgttctgcaaagactccattctggaagccatcgacgcag

  gcatcaaactgattatcaccatcactgaaggcatcccgacgctggatatgctgaccgtgaaagtgaagctggatgaa

  gcaggcgttcgtatgatcggcccgaactgcccaggcgttatcactccgggtgaatgcaaaatcggtatccagcctgg

  tcacattcacaaaccgggtaaagtgggtatcgtttcccgttccggtacactgacctatgaagcggttaaacagacca

  cggattacggtttcggtcagtcgacctgtgtcggtatcggcggtgacccgatcccgggctctaactttatcgacatt

  ctcgaaatgttcgaaaaagatccgcagaccgaagcgatcgtgatgatcggtgagatcggcggtagcgctgaagaaga

  agcagctgcgtacatcaaagagcacgttaccaagccagttgtgggttacatcgctggtgtgactgcgccgaaaggca

  aacgtatgggccacgcgggtgccatcattgccggtgggaaagggactgcggatgagaaattcgctgctctggaagcc

  gcaggcgtgaaaaccgttcgcagcctggcggatatcggtgaagcactgaaaactgttctgaaataaaggtccaggca

  tcaaataaaacgaaaggctcagtcgaaagactgggcctttcgttttatctgttgtttgtcggtgaacgctctctact

  agagtcacactggctcaccttcgggtgggcctttctgcgtttatatgccatgtcttctactagtagcggccgctgca

  gtccggcaaaaaagggcaaggtgtcaccaccctgccctttttctttaaaaccgaaaagattacttcgcgttatgcag

  gcttcctcgctcactgactcgctgcgctcggtcgttcggctgcggcgagcggtatcagctcactcaaaggcggtaat

  acggttatccacagaatcaggggataacgcaggaaagaacatgtgagcaaaaggccagcaaaaggccaggaaccgta

  aaaaggccgcgttgctggcgtttttccacaggctccgcccccctgacgagcatcacaaaaatcgacgctcaagtcag

  aggtggcgaaacccgacaggactataaagataccaggcgtttccccctggaagctccctcgtgcgctctcctgttcc

  gaccctgccgcttaccggatacctgtccgcctttctcccttcgggaagcgtggcgctttctcatagctcacgctgta

  ggtatctcagttcggtgtaggtcgttcgctccaagctgggctgtgtgcacgaaccccccgttcagcccgaccgctgc

  gccttatccggtaactatcgtcttgagtccaacccggtaagacacgacttatcgccactggcagcagccactggtaa

  caggattagcagagcgaggtatgtaggcggtgctacagagttcttgaagtggtggcctaactacggctacactagaa

  gaacagtatttggtatctgcgctctgctgaagccagttaccttcggaaaaagagttggtagctcttgatccggcaaa

  caaaccaccgctggtagcggtggtttttttgtttgcaagcagcagattacgcgcagaaaaaaaggatctcaagaaga

  tcctttgatcttttctacggggtctgacgctcagtggaacgaaaactcacgttaagggattttggtcatgagattat

  caaaaaggatcttcacctagatccttttaaattaaaaatgaagttttaaatcaatctaaagtatatatgagtaaact

  tggtctgacagctcgagtcccgtcaagtcagcgtaatgctctgccagtgttacaaccaattaaccaattctgattag

  aaaaactcatcgagcatcaaatgaaactgcaatttattcatatcaggattatcaataccatatttttgaaaaagccg

  tttctgtaatgaaggagaaaactcaccgaggcagttccataggatggcaagatcctggtatcggtctgcgattccga

  ctcgtccaacatcaatacaacctattaatttcccctcgtcaaaaataaggttatcaagtgagaaatcaccatgagtg

  acgactgaatccggtgagaatggcaaaagcttatgcatttctttccagacttgttcaacaggccagccattacgctc

  gtcatcaaaatcactcgcatcaaccaaaccgttattcattcgtgattgcgcctgagcgagacgaaatacgcgatcgc

  tgttaaaaggacaattacaaacaggaatcgaatgcaaccggcgcaggaacactgccagcgcatcaacaatattttca

  cctgaatcaggatattcttctaatacctggaatgctgttttcccggggatcgcagtggtgagtaaccatgcatcatc

  aggagtacggataaaatgcttgatggtcggaagaggcataaattccgtcagccagtttagtctgaccatctcatctg

  taacatcattggcaacgctacctttgccatgtttcagaaacaactctggcgcatcgggcttcccatacaatcgatag

  attgtcgcacctgattgcccgacattatcgcgagcccatttatacccatataaatcagcatccatgttggaatttaa

  tcgcggcctggagcaagacgtttcccgttgaatatggctcataacaccccttgtattactgtttatgtaagcagaca

  gttttattgttcatgatgatatatttttatcttgtgcaatgtaacatcagagattttgagacacaacgtggctttgt

  tgaataaatcgaacttttgctgagttgaaggatcagctcgagtgccacctgacgtctaagaaaccattattatcatg

  acattaacctataaaaataggcgtatcacgaggcagaatttcagataaaaaaaatccttagctttcgctaaggatga

  tttctggaattcgcggccgcttctagagactagtggaagacatcgctaccgtaggcctgataagacgcgcaagcgtc

  gcatcaggcaaccagtgccggatgcggcgtgaacgccttatccggcctacaagtcattacccgtaggcctgataagc

  gcagcgcatcaggcgtaacaaagaaatgcaggaaatctttaaaaactgcccctgacactaagacagtttttaaaggt

  tccttcgcgagccactacgtagacaagagctcgcaagtgaaccccggcacgcacatcactgtgcgtggtagtatcca

  cggcgaagtaagcataaaaaagatgcttaagggatcacgAATGcagaacagcgctttgaaagcctggttggactctt

  cttacctctctggcgcaaaccagagctggatagaacagctctatgaaGATttcttaaccgatcctgactcggttgac

  gctaactggcgttcgacgttccagcagttacctggtacgggagtcaaaccggatcaattccactctcaaacgcgtga

  atatttccgccgcctggcgaaagacgcttcacgttactcttcaacgatctccgaccctgacaccaatgtgaagcagg

  ttaaagtcctgcagctcattaacgcataccgcttccgtggtcaccagcatgcgaatctcgatccgctgggactgtgg

  cagcaagataaagtggccgatctggatccgtctttccacgatctgaccgaagcagacttccaggagACTttcaacgt

  cggttcatttgccagcggcaaagaaaccatgaaactcggcgagctgctggaagccctcaagcaaacctactgcggcc

  cgattggtgccgagtatatgcacattaccagcaccgaagaaaaacgctggatccaacagcgtatcgagtctggtcgc

  gcgactttcaatagcgaagagaaaaaacgcttcttaagcgaactgaccgccgctgaaggtcttgaacgttacctcgg

  cgcaaaattccctggcgcaaaacgcttctcgctggaaggcggtgacgcgttaatcccgatgcttaaagagatgatcc

  gccacgctggcaacagcggcacccgcgaagtggttctcgggatggcgcaccgtggtcgtctgaacgtgctggtgaac

  gtgctgggtaaaaaaccgcaagacttgttcgacgagttcgccggtaaacataaagaacacctcggcacgggtgacgt

  gaaataccacatgggcttctcgtctgacttccagaccgatggcggcctggtgcacctggcgctggcgtttaacccgt

  ctcaccttgagattgtaagcccggtagttatcggttctgttcgtgcccgtctggacagacttgatgagccgagcagc

  aacaaagtgctgccaatcaccatccacggtgacgccgcagtgaccgggcagggcgtggttcaggaaaccctgaacat

  gtcgaaagcgcgtggttatgaagttggcggtacggtacgtatcgttatcaacaaccaggttggtttcaccacctcta

  atccgctggatgcccgttctacgccgtactgtactgatatcggtaagatggttcaggccccgattttccacgttaac

  gcggacgatccggaagccgttgcctttgtgacccgtctggcgctcgatttccgtaacacctttaaacgtgatGTTtt

  catcgacctggtgtgctaccgccgtcacggccacaacgaagccgacgagccgagcgcaacccagccgctgatgtatc

  agaaaatcaaaaaacatccgacaccgcgcaaaatctacgctgacaagctggagcaggaaaaagtggcgacgctggaa

  gatgccaccgagatggttaacctgtaccgcgatgcgctggatgctggcgattgcgtagtggcagagtggcgtccgat

  gaacatgcactctttcacctggtcgccgtacctcaaccacgaatgggacgaagagtacccgaacaaagttgagatga

  agcgcctgcaggagctggcgaaacgcatcagcacggtgccggaagcagttgaaatgcagtctcgcgttgccaagatt

  tatggcgatcgccaggcgatggctgccggtgagaaactgttcgactggggcggtgcggaaaacctcgcttacgccac

  gctggttgatgaaggcattccggttcgcctgtcgggtGAGgactccggtcgcggtaccttcttccaccgccacgcgg

  tgatccacaaccagtctaacggttccacttacacgccgctgcaacatatccataacgggcagggcgcgttccgtgtc

  tgggactccgtactgtctgaagaagcagtgctggcgtttgaatatggttatgccaccgcagaaccacgcactctgac

  catctgggaagcgcagttcggtgacttcgccaacggtgcgcaggtggttatcgaccagttcatctcctctggcgaac

  agaaatggggccggatgtgtggtctggtgatgttgctgccgcacggttacgaagggcaggggccggagcactcctcc

  gcgcgtctggaacgttatctgcaactttgtgctgagcaaaacatgcaggtttgcgtaccgtctaccccggcacaggt

  ttaccacatgctgcgtcgtcaggcgctgcgcgggatgcgtcgtccgctggtcgtgatgtcgccgaaatccctgctgc

  gtcatccgctggcggtttccagcctcgaagaactggcgaacggcaccttcctgccagccatcggtgaaatcgacgag

  cttgatccgaagggcgtgaagcgcgtagtgatgtgttctggtaaggtttattacgacctgctggaacagcgtcgtaa

  gaacaatcaacacgatgtcgccattgtgcgtatcgagcaactctacccgttcccgcataaagcgatgcaggaagtgt

  tgcagcagtttgctcacgtcaaggattttgtctggtgccaggaagagccgctcaaccagggcgcatggtactgcagc

  cagcatcatttccgtgaagtgattccgtttggggcttctctgcgttatgcaggccgcccggcctccgcctctccggc

  ggtagggtatatgtccgttcaccagaaacagcaacaagatctggttaatgacgcgctgaacgtcgaataaataaagg

  atacacaatgagtagcgtagatattctggtccctgacctgcctgaatccgtagccgatgccaccgtcgcaacctggc

  ataaaaaacccggcgacgcagtcgtacgtgatgaagtgctggtagaaatcgaaactgacaaagtggtactggaagta

  ccggcatcagcagacggcattctggatgcggttctggaagatgaaggtacaacggtaacgtctcgtcagatccttgg

  tcgcctgcgtgaaggcaacagcgccggtaaagaaaccagcgccaaatctgaagagaaagcgtccactccggcgcaac

  gccagcaggcgtctctggaagagcaaaacaacgatgcgttaagcccggcgatccgtcgcctgctggctgaacacaat

  ctcgacgccagcgccattaaaggcaccggtgtgggtggtcgtctgactcgtgaagatgtggaaaaacatctggcgaa

  agcc

  SEQ ID NO: 6. Sequence of the pDvS vector, designed for facile cloning with a

  modular cloning system. It contains the sucAD gene pair instead of an antibiotic

  resistance marker.

  cgcgttgctggcgtttttccacaggctccgcccccctgacgagcatcacaaaaatcgacgctcaagtcagaggtggc

  gaaacccgacaggactataaagataccaggcgtttccccctggaagctccctcgtgcgctctcctgttccgaccctg

  ccgcttaccggatacctgtccgcctttctcccttcgggaagcgtggcgctttctcatagctcacgctgtaggtatct

  cagttcggtgtaggtcgttcgctccaagctgggctgtgtgcacgaaccccccgttcagcccgaccgctgcgccttat

  ccggtaactatcgtcttgagtccaacccggtaagacacgacttatcgccactggcagcagccactggtaacaggatt

  agcagagcgaggtatgtaggcggtgctacagagttcttgaagtggtggcctaactacggctacactagaagaacagt

  atttggtatctgcgctctgctgaagccagttaccttcggaaaaagagttggtagctcttgatccggcaaacaaacca

  ccgctggtagcggtggtttttttgtttgcaagcagcagattacgcgcagaaaaaaaggatctcaagaagatcctttg

  atcttttctacggggtctgacgctcagtggaacgaaaactcacgttaagggattttggtcatgagattatcaaaaag

  gatcttcacctagatccttttaaattaaaaatgaagttttaaatcaatctaaagtatatatgagtaaacttggtctg

  acagctcgagtttacggctagctcagtcctaggtatagtgctagcTACTtgttagaaaagagaagcacgtaatgcag

  aactcagcattgaaagcatggcttgatagctcctatttatcaggtgctaaccagagctggattgaacagctgtatga

  agattttctgacagatccggattcagtggatgcgaattggcgcagcacttttcagcagttgcctggcaccggtgtaa

  aaccggatcagtttcattcccagacgcgggagtattttcgtcgtctggcgaaagatgcgagccggtattcaagtaca

  atttctgatccggatacgaatgtaaaacaggtgaaagtgcttcagttaattaatgcgtatcgctttagaggccatca

  gcatgcgaatctggatccgctgggcttatggcagcaggataaagtcgcggatctggatccaagttttcacgatttaa

  cggaagctgattttcaggaaacctttaacgtcggctcattcgcaagtgggaaagaaacaatgaaactgggcgaactt

  cttgaggcgctgaaacagacttattgtggccctattggtgcggaatatatgcatattacctcaactgaagagaaacg

  ttggattcagcagagaatcgagagtggccgcgcgacttttaactccgaagaaaaaaaaagattcctgtcagaactga

  cagccgcggaaggcttagagcggtatttgggtgccaaattcccaggagcaaaacggttcagcctggagggcggtgat

  gcgctgatcccgatgctgaaagaaatgattcggcatgcgggaaatagcggaactcgggaagtggtgttaggaatggc

  acaccgcggccgtttgaatgtactggttaacgtattaggaaaaaaacctcaggatttatttgatgagttcgcgggaa

  aacataaagaacatctgggcactggtgatgtcaaatatcacatgggcttctcaagtgattttcagacggatggaggt

  ctggttcacctggcactggcatttaatccttctcatctggaaatcgtaagtccggtcgttattggttccgtgcgcgc

  tcgcttagatcggttagatgaacctagctcaaacaaagttttaccaatcacgatccatggggatgcagctgttaccg

  gacagggtgttgtgcaggagactttgaatatgtccaaagcgcgcgggtatgaggtgggtggtacggtgcgtattgtt

  atcaataatcaggtgggttttacaaccagtaaccctctggatgctcgctctacgccgtattgcactgatattggtaa

  aatggtgcaggcaccaatttttcacgtcaatgccgatgatccggaagctgttgcctttgttacgcgcctggctctgg

  attttcgtaacactttcaaacgtgatgtatttatcgatttagtatgctatcgtcgtcatggtcataatgaggctgat

  gaacctagcgctacccagccactgatgtatcagaaaattaaaaaacatcctacccctcgtaaaatttatgcggataa

  actggagcaggaaaaagtggctactcttgaagatgctactgaaatggtcaatctttatcgggatgcattggatgcgg

  gtgattgcgtggtcgcggaatggcgcccgatgaatatgcattcatttacttggtcaccgtatttaaatcatgagtgg

  gatgaggaatatccgaataaagtggagatgaaacgcctgcaggaattagcaaaacgtattagcacagtacctgaagc

  ggttgagatgcagtctagagttgccaaaatctatggagatcgccaggccatggcagcaggggaaaaactttttgatt

  gggggggagccgaaaacctggcatatgcgacgctggtagatgagggcattccggtgcgcctttctggtgaagattct

  gggcgcggtactttttttcatcggcacgctgttattcataaccagtctaacggtagtacttatactccgctgcagca

  catccacaatggtcagggtgcgttccgtgtatgggattccgtgctgagtgaagaagcggttcttgcgtttgagtatg

  ggtatgcaactgccgagccacgcacgctgacgatctgggaagcccagtttggcgattttgcaaatggtgcccaggtg

  gtaatcgatcagtttattagctccggcgaacagaaatgggggcggatgtgtggtttagttatgttgttaccgcatgg

  ctatgaaggtcagggacctgagcacagctcagcgcgcctggaacgctatcttcagctgtgtgcggaacagaacatgc

  aggtatgcgttccttccacgccggctcaggtttatcatatgttaagacgtcaggccttgcgcggtatgcggcgcccg

  ttggtcgtgatgtccccgaaaagtttactgcgccatccgttagcagttagcagcctggaggaactggcaaacggtac

  gttcttgccagctatcggcgaaatcgatgaactggatcctaaaggggtgaaacgcgttgttatgtgttctggtaaag

  tgtattatgatcttttggaacagcgtcgcaaaaataatcagcacgatgtagctattgtgcggatcgagcagctgtat

  ccgttcccgcacaaagcaatgcaggaagtgctgcagcagttcgcacatgtcaaagattttgtctggtgtcaggagga

  accgcttaatcagggggcctggtattgtagtcagcaccatttccgggaggtgatcccgtttggggcgtccttacggt

  atgctggtcgccctgcctccgcaagtccggccgtgggatatatgagcgttcaccagaaacagcagcaggatttggtg

  aatgatgctttgaatgtggaatgaatgtccatcctgatcgacaaaaacactaaagtaatttgtcagggctttaccgg

  ttcccagggcacatttcactcagagcaggccatcgcttatgggaccaaaatggtgggtggtgtaacgcctggtaaag

  gaggcaccacccatctgggtttgccggtatttaataccgtgcgtgaggcggttgccgcaaccggtgccacggcttca

  gttatctatgttcctgccccattttgtaaagattcaattctggaagctattgatgcgggcatcaaattgattattac

  gattaccgaaggtatccctacgctggatatgttgacggttaaagtgaaacttgatgaagcgggggtacgcatgattg

  gtccgaattgtccgggcgttattactccaggtgagtgcaaaattggtattcagccgggtcatattcacaaacctggg

  aaagtcggaattgtgtctcgttctggcactctgacgtatgaggcagttaaacagaccacagattatggctttgggca

  gagtacctgtgtcggcatcggaggcgatcctattccggggagtaattttatcgatattctggaaatgtttgagaaag

  atccgcagaccgaggcaatcgtcatgattggcgagattggcggttccgcggaagaagaagctgcagcctatatcaaa

  gaacatgtcacaaaaccggtagtgggctatatcgcgggagtcacggccccaaaaggtaaacgtatgggccatgccgg

  agcgatcatcgcgggcggcaaaggcactgcagatgaaaaatttgcagcccttgaggccgctggcgtaaaaacggtcc

  gttcccttgctgatattggtgaagcactgaaaaccgtgttgaaataaAGGTccaggcatcaaataaaacgaaaggct

  cagtcgaaagactgggcctttcgttttatctgttgtttgtcggtgaacgctctctactagagtcacactggctcacc

  ttcgggtgggcctttctgcgtttatactcgagtgccacctgacgtctaagaaaccattattatcatgacattaacct

  ataaaaataggcgtatcacgaggcagaatttcagataaaaaaaatccttagctttcgctaaggatgatttctggaat

  tcgcggccgcttctagagactagtggaagacatcgctagagacctgcaccatatgcggtgtgaaataccgcacagat

  gcgtaaggagaaaataccgcatcaggcgccattcgccattcaggctgcgcaactgttgggaagggcgatcggtgcgg

  gcctcttcgctattacgccagctggcgaaagggggatgtgctgcaaggcgattaagttgggtaacgccagggttttc

  ccagtcacgacgttgtaaaacgacggccagtgaattcgagctcggtacccggggatcctctagagtcgacctgcagg

  catgcaagcttggcgtaatcatggtcatagctgtttcctgtgtgaaattgttatccgctcacaattccacacaacat

  acgagccggaagcataaagtgtaaagcctggggtgcctaatgagtgagctaactcacattaattgcgttgcgctcac

  tgcccgctttccagtcgggaaacctgtcgtgccagctgcattaatgaatcggccaacgcgcgggggtttataaaatc

  ccgtcaagtcagcgtaatgctctgccagtgttacaaccaattaaccaattctgattagaaaaactcatcgagcatca

  aatgaaactgcaatttattcatatcaggattatcaataccatatttttgaaaaagccgtttctgtaatgaaggagaa

  aactcaccgaggcagttccataggatggcaagatcctggtatcggtctgcgattccgactcgtccaacatcaataca

  acctattaatttcccctcgtcaaaaataaggttatcaagtgagaaatcaccatgagtgacgactgaatccggtgaga

  atggcaaaagcttatgcatttctttccagacttgttcaacaggccagccattacgctcgtcatcaaaatcactcgca

  tcaaccaaaccgttattcattcgtgattgcgcctgagcgagacgaaatacgcgatcgctgttaaaaggacaattaca

  aacaggaatcgaatgcaaccggcgcaggaacactgccagcgcatcaacaatattttcacctgaatcaggatattctt

  ctaatacctggaatgctgttttcccggggatcgcagtggtgagtaaccatgcatcatcaggagtacggataaaatgc

  ttgatggtcggaagaggcataaattccgtcagccagtttagtctgaccatctcatctgtaacatcattggcaacgct

  acctttgccatgtttcagaaacaactctggcgcatcgggcttcccatacaatcgatagattgtcgcacctgattgcc

  cgacattatcgcgagcccatttatacccatataaatcagcatccatgttggaatttaatcgcggcctggagcaagac

  gtttcccgttgaatatggctcataacaccccttgtattactgtttatgtaagcagacagttttattgttcatgatga

  tatatttttatcttgtgcaatgtaacatcagagattttgagacacaacgtggctttgttgaataaatcgaacttttg

  ctgagttgaaggatcagggtctcttgccatgtcttctactagtagcggccgctgcagtccggcaaaaaagggcaagg

  tgtcaccaccctgccctttttctttaaaaccgaaaagattacttcgcgttatgcaggcttcctcgctcactgactcg

  ctgcgctcggtcgttcggctgcggcgagcggtatcagctcactcaaaggcggtaatacggttatccacagaatcagg

  ggataacgcaggaaagaacatgtgagcaaaaggccagcaaaaggccaggaaccgtaaaaaggc

  SEQ ID NO: 7. Sequence of the pDvQ vector, designed for facile cloning with a

  modular cloning system. It contains the entire sucABCD operon including native

  5′ UTR instead of an antibiotic resistance marker.

  cgcgttgctggcgtttttccacaggctccgcccccctgacgagcatcacaaaaatcgacgctcaagtcagaggtggc

  gaaacccgacaggactataaagataccaggcgtttccccctggaagctccctcgtgcgctctcctgttccgaccctg

  ccgcttaccggatacctgtccgcctttctcccttcgggaagcgtggcgctttctcatagctcacgctgtaggtatct

  cagttcggtgtaggtcgttcgctccaagctgggctgtgtgcacgaaccccccgttcagcccgaccgctgcgccttat

  ccggtaactatcgtcttgagtccaacccggtaagacacgacttatcgccactggcagcagccactggtaacaggatt

  agcagagcgaggtatgtaggcggtgctacagagttcttgaagtggtggcctaactacggctacactagaagaacagt

  atttggtatctgcgctctgctgaagccagttaccttcggaaaaagagttggtagctcttgatccggcaaacaaacca

  ccgctggtagcggtggtttttttgtttgcaagcagcagattacgcgcagaaaaaaaggatctcaagaagatcctttg

  atcttttctacggggtctgacgctcagtggaacgaaaactcacgttaagggattttggtcatgagattatcaaaaag

  gatcttcacctagatccttttaaattaaaaatgaagttttaaatcaatctaaagtatatatgagtaaacttggtctg

  acagctcgaggtaggcctgataagacgcgcaagcgtcgcatcaggcaaccagtgccggatgcggcgtgaacgcctta

  tccggcctacaagtcattacccgtaggcctgataagcgcagcgcatcaggcgtaacaaagaaatgcaggaaatcttt

  aaaaactgcccctgacactaagacagtttttaaaggttccttcgcgagccactacgtagacaagagctcgcaagtga

  accccggcacgcacatcactgtgcgtggtagtatccacggcgaagtaagcataaaaaagatgcttaagggatcacgA

  ATGcagaacagcgctttgaaagcctggttggactcttcttacctctctggcgcaaaccagagctggatagaacagct

  ctatgaaGATttcttaaccgatcctgactcggttgacgctaactggcgttcgacgttccagcagttacctggtacgg

  gagtcaaaccggatcaattccactctcaaacgcgtgaatatttccgccgcctggcgaaagacgcttcacgttactct

  tcaacgatctccgaccctgacaccaatgtgaagcaggttaaagtcctgcagctcattaacgcataccgcttccgtgg

  tcaccagcatgcgaatctcgatccgctgggactgtggcagcaagataaagtggccgatctggatccgtctttccacg

  atctgaccgaagcagacttccaggagACTttcaacgtcggttcatttgccagcggcaaagaaaccatgaaactcggc

  gagctgctggaagccctcaagcaaacctactgcggcccgattggtgccgagtatatgcacattaccagcaccgaaga

  aaaacgctggatccaacagcgtatcgagtctggtcgcgcgactttcaatagcgaagagaaaaaacgcttcttaagcg

  aactgaccgccgctgaaggtcttgaacgttacctcggcgcaaaattccctggcgcaaaacgcttctcgctggaaggc

  ggtgacgcgttaatcccgatgcttaaagagatgatccgccacgctggcaacagcggcacccgcgaagtggttctcgg

  gatggcgcaccgtggtcgtctgaacgtgctggtgaacgtgctgggtaaaaaaccgcaagacttgttcgacgagttcg

  ccggtaaacataaagaacacctcggcacgggtgacgtgaaataccacatgggcttctcgtctgacttccagaccgat

  ggcggcctggtgcacctggcgctggcgtttaacccgtctcaccttgagattgtaagcccggtagttatcggttctgt

  tcgtgcccgtctggacagacttgatgagccgagcagcaacaaagtgctgccaatcaccatccacggtgacgccgcag

  tgaccgggcagggcgtggttcaggaaaccctgaacatgtcgaaagcgcgtggttatgaagttggcggtacggtacgt

  atcgttatcaacaaccaggttggtttcaccacctctaatccgctggatgcccgttctacgccgtactgtactgatat

  cggtaagatggttcaggccccgattttccacgttaacgcggacgatccggaagccgttgcctttgtgacccgtctgg

  cgctcgatttccgtaacacctttaaacgtgatGTTttcatcgacctggtgtgctaccgccgtcacggccacaacgaa

  gccgacgagccgagcgcaacccagccgctgatgtatcagaaaatcaaaaaacatccgacaccgcgcaaaatctacgc

  tgacaagctggagcaggaaaaagtggcgacgctggaagatgccaccgagatggttaacctgtaccgcgatgcgctgg

  atgctggcgattgcgtagtggcagagtggcgtccgatgaacatgcactctttcacctggtcgccgtacctcaaccac

  gaatgggacgaagagtacccgaacaaagttgagatgaagcgcctgcaggagctggcgaaacgcatcagcacggtgcc

  ggaagcagttgaaatgcagtctcgcgttgccaagatttatggcgatcgccaggcgatggctgccggtgagaaactgt

  tcgactggggcggtgcggaaaacctcgcttacgccacgctggttgatgaaggcattccggttcgcctgtcgggtGAG

  gactccggtcgcggtaccttcttccaccgccacgcggtgatccacaaccagtctaacggttccacttacacgccgct

  gcaacatatccataacgggcagggcgcgttccgtgtctgggactccgtactgtctgaagaagcagtgctggcgtttg

  aatatggttatgccaccgcagaaccacgcactctgaccatctgggaagcgcagttcggtgacttcgccaacggtgcg

  caggtggttatcgaccagttcatctcctctggcgaacagaaatggggccggatgtgtggtctggtgatgttgctgcc

  gcacggttacgaagggcaggggccggagcactcctccgcgcgtctggaacgttatctgcaactttgtgctgagcaaa

  acatgcaggtttgcgtaccgtctaccccggcacaggtttaccacatgctgcgtcgtcaggcgctgcgcgggatgcgt

  cgtccgctggtcgtgatgtcgccgaaatccctgctgcgtcatccgctggcggtttccagcctcgaagaactggcgaa

  cggcaccttcctgccagccatcggtgaaatcgacgagcttgatccgaagggcgtgaagcgcgtagtgatgtgttctg

  gtaaggtttattacgacctgctggaacagcgtcgtaagaacaatcaacacgatgtcgccattgtgcgtatcgagcaa

  ctctacccgttcccgcataaagcgatgcaggaagtgttgcagcagtttgctcacgtcaaggattttgtctggtgcca

  ggaagagccgctcaaccagggcgcatggtactgcagccagcatcatttccgtgaagtgattccgtttggggcttctc

  tgcgttatgcaggccgcccggcctccgcctctccggcggtagggtatatgtccgttcaccagaaacagcaacaagat

  ctggttaatgacgcgctgaacgtcgaataaataaaggatacacaatgagtagcgtagatattctggtccctgacctg

  cctgaatccgtagccgatgccaccgtcgcaacctggcataaaaaacccggcgacgcagtcgtacgtgatgaagtgct

  ggtagaaatcgaaactgacaaagtggtactggaagtaccggcatcagcagacggcattctggatgcggttctggaag

  atgaaggtacaacggtaacgtctcgtcagatccttggtcgcctgcgtgaaggcaacagcgccggtaaagaaaccagc

  gccaaatctgaagagaaagcgtccactccggcgcaacgccagcaggcgtctctggaagagcaaaacaacgatgcgtt

  aagcccggcgatccgtcgcctgctggctgaacacaatctcgacgccagcgccattaaaggcaccggtgtgggtggtc

  gtctgactcgtgaagatgtggaaaaacatctggcgaaagccccggcgaaagagtctgctccggcagcggctgctccg

  gcggcgcaaccggctctggctgcacgtagtgaaaaacgtgtcccgatgactcgcctgcgtaagcgtgtggcagagcg

  tctgctggaagcgaaaaactccaccgccatgctgaccacgttcaacgaagtcaacatgaagccgattatggatctgc

  gtaagcagtacggtgaagcgtttgaaaaacgccacggcatccgtctgggctttatgtccttctacgtgaaagcggtg

  gttgaagccctgaaacgttacccggaagtgaacgcttctatcgacggcgatgacgtggtttaccacaactatttcga

  cgtcagcatggcggtttctacgccgcgcggcctggtgacgccggttctgcgtgatgtcgataccctcggcatggcag

  acatcgagaagaaaatcaaagagctggcagtcaaaggccgtgacggcaagctgaccgttgaagatctgaccggtggt

  aacttcaccatcaccaacggtggtgtgttcggttccctgatgtctacgccgatcatcaacccgccgcagagcgcaat

  tctgggtatgcacgctatcaaagatcgtccgatggcggtgaatggtcaggttgagatcctgccgatgatgtacctgg

  cgctgtcctacgatcaccgtctgatcgatggtcgcgaatccgtgggcttcctggtaacgatcaaagagttgctggaa

  gatccgacgcgtctgctgctggacgtgtagtagtttaagtttcacctgcactgtagaccggataaggcattatcgcc

  ttctccggcaattgaagcctgatgcgacgctgacgcgtcttatcaggcctacgggaccaccaatgtaggtcggataa

  ggcgcaagcgccgcatccgacaagcgatgcctgatgtgacgtttaacgtgtcttatcaggcctacgggtgaccgaca

  atgcccggaagcgatacgaaatattcGGTCTACGGTTTAAAAGATAACGATTACTGAAGGATGGACAGAACACatga

  acttacatgaatatcaggcaaaacaactttttgcccgctatggcttaccagcaccggtgggttatgcctgtactact

  ccgcgcgaagcagaagaagccgcttcaaaaatcggtgccggtccgtgggtagtgaaatgtcaggttcacgctggtgg

  ccgcggtaaagcgggcggtgtgaaagttgtaaacagcaaaGAGgacatccgtgcttttgcagaaaactggctgggca

  agcgtctggtaacgtatcaaacagatgccaatggccaaccggttaaccagattctggttgaagcagcgaccgatatc

  gctaaagagctgtatctcggtgccgttgttgaccgtagttcccgtcgtgtggtctttatggcctccaccgaaggcgg

  cgtggaaatcgaaaaagtggcggaagaaactccgcacctgatccataaagttgcgcttgatccgctgactggcccga

  tgccgtatcagggacgcgagctggcgttcaaactgggtctggaaggtaaactggttcagcagttcaccaaaatcttc

  atgggcctggcgaccattttcctggagcgcgacctggcgttgatcgaaatcaacccgctggtcatcaccaaacaggg

  cgatctgatttgcctcgacggcaaactgggcgctgacggcaacgcactgttccgccagcctgatctgcgcgaaatgc

  gtgaccagtcgcaggaagatccgcgtgaagcacaggctgcacagtgggaactgaactacgttgcgctggacggtaac

  atcggttgtatggttaacggcgcaggtctggcgatgggtacgatggacatcgttaaactgcacggcggcgaaccggc

  taacttccttgacgttggcggcggcgcaaccaaagaacgtgtaaccgaagcgttcaaaatcatcctctctgacgaca

  aagtgaaagccgttctggttaacatcttcggcggtatcgttcgttgcgacctgatcgctgacggtatcatcggcgcg

  gtagcagaagtgggtgttaacgtaccggtcgtggtacgtctggaaggtaacaacgccgaactcggcgcgaagaaact

  ggctgacagcggcctgaatattattgcagcaaaaggtctgacggatgcagctcagcaggttgttgccgcagtggagg

  ggaaataatgtccattttaatcgataaaaacaccaaggttatctgccagggctttaccggtagccaggggactttcc

  actcagaacaggccattgcatacggcactaaaatggttggcggcgtaaccccaggtaaaggcggcaccacccacctc

  ggcctgccggtgttcaacaccgtgcgtgaagccgttgctgccactggcgctaccgcttctgttatctacgtaccagc

  accgttctgcaaagactccattctggaagccatcgacgcaggcatcaaactgattatcaccatcactgaaggcatcc

  cgacgctggatatgctgaccgtgaaagtgaagctggatgaagcaggcgttcgtatgatcggcccgaactgcccaggc

  gttatcactccgggtgaatgcaaaatcggtatccagcctggtcacattcacaaaccgggtaaagtgggtatcgtttc

  ccgttccggtacactgacctatgaagcggttaaacagaccacggattacggtttcggtcagtcgacctgtgtcggta

  tcggcggtgacccgatcccgggctctaactttatcgacattctcgaaatgttcgaaaaagatccgcagaccgaagcg

  atcgtgatgatcggtgagatcggcggtagcgctgaagaagaagcagctgcgtacatcaaagagcacgttaccaagcc

  agttgtgggttacatcgctggtgtgactgcgccgaaaggcaaacgtatgggccacgcgggtgccatcattgccggtg

  ggaaagggactgcggatgagaaattcgctgctctggaagccgcaggcgtgaaaaccgttcgcagcctggcggatatc

  ggtgaagcactgaaaactgttctgaaataaaggtccaggcatcaaataaaacgaaaggctcagtcgaaagactgggc

  ctttcgttttatctgttgtttgtcggtgaacgctctctactagagtcacactggctcaccttcgggtgggcctttct

  gcgtttatactcgagtgccacctgacgtctaagaaaccattattatcatgacattaacctataaaaataggcgtatc

  acgaggcagaatttcagataaaaaaaatccttagctttcgctaaggatgatttctggaattcgcggccgcttctaga

  gactagtggaagacatcgctagagacctgcaccatatgcggtgtgaaataccgcacagatgcgtaaggagaaaatac

  cgcatcaggcgccattcgccattcaggctgcgcaactgttgggaagggcgatcggtgcgggcctcttcgctattacg

  ccagctggcgaaagggggatgtgctgcaaggcgattaagttgggtaacgccagggttttcccagtcacgacgttgta

  aaacgacggccagtgaattcgagctcggtacccggggatcctctagagtcgacctgcaggcatgcaagcttggcgta

  atcatggtcatagctgtttcctgtgtgaaattgttatccgctcacaattccacacaacatacgagccggaagcataa

  agtgtaaagcctggggtgcctaatgagtgagctaactcacattaattgcgttgcgctcactgcccgctttccagtcg

  ggaaacctgtcgtgccagctgcattaatgaatcggccaacgcgcgggggtttataaaatcccgtcaagtcagcgtaa

  tgctctgccagtgttacaaccaattaaccaattctgattagaaaaactcatcgagcatcaaatgaaactgcaattta

  ttcatatcaggattatcaataccatatttttgaaaaagccgtttctgtaatgaaggagaaaactcaccgaggcagtt

  ccataggatggcaagatcctggtatcggtctgcgattccgactcgtccaacatcaatacaacctattaatttcccct

  cgtcaaaaataaggttatcaagtgagaaatcaccatgagtgacgactgaatccggtgagaatggcaaaagcttatgc

  atttctttccagacttgttcaacaggccagccattacgctcgtcatcaaaatcactcgcatcaaccaaaccgttatt

  cattcgtgattgcgcctgagcgagacgaaatacgcgatcgctgttaaaaggacaattacaaacaggaatcgaatgca

  accggcgcaggaacactgccagcgcatcaacaatattttcacctgaatcaggatattcttctaatacctggaatgct

  gttttcccggggatcgcagtggtgagtaaccatgcatcatcaggagtacggataaaatgcttgatggtcggaagagg

  cataaattccgtcagccagtttagtctgaccatctcatctgtaacatcattggcaacgctacctttgccatgtttca

  gaaacaactctggcgcatcgggcttcccatacaatcgatagattgtcgcacctgattgcccgacattatcgcgagcc

  catttatacccatataaatcagcatccatgttggaatttaatcgcggcctggagcaagacgtttcccgttgaatatg

  gctcataacaccccttgtattactgtttatgtaagcagacagttttattgttcatgatgatatatttttatcttgtg

  caatgtaacatcagagattttgagacacaacgtggctttgttgaataaatcgaacttttgctgagttgaaggatcag

  ggtctcttgccatgtcttctactagtagcggccgctgcagtccggcaaaaaagggcaaggtgtcaccaccctgccct

  ttttctttaaaaccgaaaagattacttcgcgttatgcaggcttcctcgctcactgactcgctgcgctcggtcgttcg

  gctgcggcgagcggtatcagctcactcaaaggcggtaatacggttatccacagaatcaggggataacgcaggaaaga

  acatgtgagcaaaaggccagcaaaaggccaggaaccgtaaaaaggc

  SEQ ID NO: 8. Sequence of Plasmid pDvS-GFP containing a sequence encoding the

  green fluorescent protein cloned into the pDvS vector

  tactgcgccatccgttagcagttagcagcctggaggaactggcaaacggtacgttcttgccagctatcggcgaaatc

  gatgaactggatcctaaaggggtgaaacgcgttgttatgtgttctggtaaagtgtattatgatcttttggaacagcg

  tcgcaaaaataatcagcacgatgtagctattgtgcggatcgagcagctgtatccgttcccgcacaaagcaatgcagg

  aagtgctgcagcagttcgcacatgtcaaagattttgtctggtgtcaggaggaaccgcttaatcagggggcctggtat

  tgtagtcagcaccatttccgggaggtgatcccgtttggggcgtccttacggtatgctggtcgccctgcctccgcaag

  tccggccgtgggatatatgagcgttcaccagaaacagcagcaggatttggtgaatgatgctttgaatgtggaatgaa

  tgtccatcctgatcgacaaaaacactaaagtaatttgtcagggctttaccggttcccagggcacatttcactcagag

  caggccatcgcttatgggaccaaaatggtgggtggtgtaacgcctggtaaaggaggcaccacccatctgggtttgcc

  ggtatttaataccgtgcgtgaggcggttgccgcaaccggtgccacggcttcagttatctatgttcctgccccatttt

  gtaaagattcaattctggaagctattgatgcgggcatcaaattgattattacgattaccgaaggtatccctacgctg

  gatatgttgacggttaaagtgaaacttgatgaagcgggggtacgcatgattggtccgaattgtccgggcgttattac

  tccaggtgagtgcaaaattggtattcagccgggtcatattcacaaacctgggaaagtcggaattgtgtctcgttctg

  gcactctgacgtatgaggcagttaaacagaccacagattatggctttgggcagagtacctgtgtcggcatcggaggc

  gatcctattccggggagtaattttatcgatattctggaaatgtttgagaaagatccgcagaccgaggcaatcgtcat

  gattggcgagattggcggttccgcggaagaagaagctgcagcctatatcaaagaacatgtcacaaaaccggtagtgg

  gctatatcgcgggagtcacggccccaaaaggtaaacgtatgggccatgccggagcgatcatcgcgggcggcaaaggc

  actgcagatgaaaaatttgcagcccttgaggccgctggcgtaaaaacggtccgttcccttgctgatattggtgaagc

  actgaaaaccgtgttgaaataaAGGTccaggcatcaaataaaacgaaaggctcagtcgaaagactgggcctttcgtt

  ttatctgttgtttgtcggtgaacgctctctactagagtcacactggctcaccttcgggtgggcctttctgcgtttat

  atcccgtcaagtcagcgtaatgctctgccagtgttacaaccaattaaccaattctgattagaaaaactcatcgagca

  tcaaatgaaactgcaatttattcatatcaggattatcaataccatatttttgaaaaagccgtttctgtaatgaagga

  gaaaactcaccgaggcagttccataggatggcaagatcctggtatcggtctgcgattccgactcgtccaacatcaat

  acaacctattaatttcccctcgtcaaaaataaggttatcaagtgagaaatcaccatgagtgacgactgaatccggtg

  agaatggcaaaagcttatgcatttctttccagacttgttcaacaggccagccattacgctcgtcatcaaaatcactc

  gcatcaaccaaaccgttattcattcgtgattgcgcctgagcgagacgaaatacgcgatcgctgttaaaaggacaatt

  acaaacaggaatcgaatgcaaccggcgcaggaacactgccagcgcatcaacaatattttcacctgaatcaggatatt

  cttctaatacctggaatgctgttttcccggggatcgcagtggtgagtaaccatgcatcatcaggagtacggataaaa

  tgcttgatggtcggaagaggcataaattccgtcagccagtttagtctgaccatctcatctgtaacatcattggcaac

  gctacctttgccatgtttcagaaacaactctggcgcatcgggcttcccatacaatcgatagattgtcgcacctgatt

  gcccgacattatcgcgagcccatttatacccatataaatcagcatccatgttggaatttaatcgcggcctggagcaa

  gacgtttcccgttgaatatggctcataacaccccttgtattactgtttatgtaagcagacagttttattgttcatga

  tgatatatttttatcttgtgcaatgtaacatcagagattttgagacacaacgtggctttgttgaataaatcgaactt

  ttgctgagttgaaggatcagctcgagtgccacctgacgtctaagaaaccattattatcatgacattaacctataaaa

  ataggcgtatcacgaggcagaatttcagataaaaaaaatccttagctttcgctaaggatgatttctggaattcgcgg

  ccgcttctagagactagtggaagacatcgctggaaagtgaaacgtgatttcatgcgtcattttgaacattttgtaaa

  tcttatttaataatgtgtgcggcaattcacatttaatttatgaatgttttcttaacatcgcggcaactcaagaaacg

  gcaggttcggatcttagctactagagaaagaggagaaatactagatgcgtaaaggcgaagagctgttcactggtgtc

  gtccctattctggtggaactggatggtgatgtcaacggtcataagttttccgtgcgtggcgagggtgaaggtgacgc

  aactaatggtaaactgacgctgaagttcatctgtactactggtaaactgccggttccttggccgactctggtaacga

  cgctgacttatggtgttcagtgctttgctcgttatccggaccatatgaagcagcatgacttcttcaagtccgccatg

  ccggaaggctatgtgcaggaacgcacgatttcctttaaggatgacggcacgtacaaaacgcgtgcggaagtgaaatt

  tgaaggcgataccctggtaaaccgcattgagctgaaaggcattgactttaaagaggacggcaatatcctgggccata

  agctggaatacaattttaacagccacaatgtttacatcaccgccgataaacaaaaaaatggcattaaagcgaatttt

  aaaattcgccacaacgtggaggatggcagcgtgcagctggctgatcactaccagcaaaacactccaatcggtgatgg

  tcctgttctgctgccagacaatcactatctgagcacgcaaagcgttctgtctaaagatccgaacgagaaacgcgatc

  atatggttctgctggagttcgtaaccgcagcgggcatcacgcatggtatggatgaactgtacaaatgaccaggcatc

  aaataaaacgaaaggctcagtcgaaagactgggcctttcgttttatctgttgtttgtcggtgaacgctctctactag

  agtcacactggctcaccttcgggtgggcctttctgcgtttatacgtgccatgtcttctactagtagcggccgctgca

  gtccggcaaaaaagggcaaggtgtcaccaccctgccctttttctttaaaaccgaaaagattacttcgcgttatgcag

  gcttcctcgctcactgactcgctgcgctcggtcgttcggctgcggcgagcggtatcagctcactcaaaggcggtaat

  acggttatccacagaatcaggggataacgcaggaaagaacatgtgagcaaaaggccagcaaaaggccaggaaccgta

  aaaaggccgcgttgctggcgtttttccacaggctccgcccccctgacgagcatcacaaaaatcgacgctcaagtcag

  aggtggcgaaacccgacaggactataaagataccaggcgtttccccctggaagctccctcgtgcgctctcctgttcc

  gaccctgccgcttaccggatacctgtccgcctttctcccttcgggaagcgtggcgctttctcatagctcacgctgta

  ggtatctcagttcggtgtaggtcgttcgctccaagctgggctgtgtgcacgaaccccccgttcagcccgaccgctgc

  gccttatccggtaactatcgtcttgagtccaacccggtaagacacgacttatcgccactggcagcagccactggtaa

  caggattagcagagcgaggtatgtaggcggtgctacagagttcttgaagtggtggcctaactacggctacactagaa

  gaacagtatttggtatctgcgctctgctgaagccagttaccttcggaaaaagagttggtagctcttgatccggcaaa

  caaaccaccgctggtagcggtggtttttttgtttgcaagcagcagattacgcgcagaaaaaaaggatctcaagaaga

  tcctttgatcttttctacggggtctgacgctcagtggaacgaaaactcacgttaagggattttggtcatgagattat

  caaaaaggatcttcacctagatccttttaaattaaaaatgaagttttaaatcaatctaaagtatatatgagtaaact

  tggtctgacagctcgagtttacggctagctcagtcctaggtatagtgctagcTACTtgttagaaaagagaagcacgt

  aatgcagaactcagcattgaaagcatggcttgatagctcctatttatcaggtgctaaccagagctggattgaacagc

  tgtatgaagattttctgacagatccggattcagtggatgcgaattggcgcagcacttttcagcagttgcctggcacc

  ggtgtaaaaccggatcagtttcattcccagacgcgggagtattttcgtcgtctggcgaaagatgcgagccggtattc

  aagtacaatttctgatccggatacgaatgtaaaacaggtgaaagtgcttcagttaattaatgcgtatcgctttagag

  gccatcagcatgcgaatctggatccgctgggcttatggcagcaggataaagtcgcggatctggatccaagttttcac

  gatttaacggaagctgattttcaggaaacctttaacgtcggctcattcgcaagtgggaaagaaacaatgaaactggg

  cgaacttcttgaggcgctgaaacagacttattgtggccctattggtgcggaatatatgcatattacctcaactgaag

  agaaacgttggattcagcagagaatcgagagtggccgcgcgacttttaactccgaagaaaaaaaaagattcctgtca

  gaactgacagccgcggaaggcttagagcggtatttgggtgccaaattcccaggagcaaaacggttcagcctggaggg

  cggtgatgcgctgatcccgatgctgaaagaaatgattcggcatgcgggaaatagcggaactcgggaagtggtgttag

  gaatggcacaccgcggccgtttgaatgtactggttaacgtattaggaaaaaaacctcaggatttatttgatgagttc

  gcgggaaaacataaagaacatctgggcactggtgatgtcaaatatcacatgggcttctcaagtgattttcagacgga

  tggaggtctggttcacctggcactggcatttaatccttctcatctggaaatcgtaagtccggtcgttattggttccg

  tgcgcgctcgcttagatcggttagatgaacctagctcaaacaaagttttaccaatcacgatccatggggatgcagct

  gttaccggacagggtgttgtgcaggagactttgaatatgtccaaagcgcgcgggtatgaggtgggtggtacggtgcg

  tattgttatcaataatcaggtgggttttacaaccagtaaccctctggatgctcgctctacgccgtattgcactgata

  ttggtaaaatggtgcaggcaccaatttttcacgtcaatgccgatgatccggaagctgttgcctttgttacgcgcctg

  gctctggattttcgtaacactttcaaacgtgatgtatttatcgatttagtatgctatcgtcgtcatggtcataatga

  ggctgatgaacctagcgctacccagccactgatgtatcagaaaattaaaaaacatcctacccctcgtaaaatttatg

  cggataaactggagcaggaaaaagtggctactcttgaagatgctactgaaatggtcaatctttatcgggatgcattg

  gatgcgggtgattgcgtggtcgcggaatggcgcccgatgaatatgcattcatttacttggtcaccgtatttaaatca

  tgagtgggatgaggaatatccgaataaagtggagatgaaacgcctgcaggaattagcaaaacgtattagcacagtac

  ctgaagcggttgagatgcagtctagagttgccaaaatctatggagatcgccaggccatggcagcaggggaaaaactt

  tttgattgggggggagccgaaaacctggcatatgcgacgctggtagatgagggcattccggtgcgcctttctggtga

  agattctgggcgcggtactttttttcatcggcacgctgttattcataaccagtctaacggtagtacttatactccgc

  tgcagcacatccacaatggtcagggtgcgttccgtgtatgggattccgtgctgagtgaagaagcggttcttgcgttt

  gagtatgggtatgcaactgccgagccacgcacgctgacgatctgggaagcccagtttggcgattttgcaaatggtgc

  ccaggtggtaatcgatcagtttattagctccggcgaacagaaatgggggcggatgtgtggtttagttatgttgttac

  cgcatggctatgaaggtcagggacctgagcacagctcagcgcgcctggaacgctatcttcagctgtgtgcggaacag

  aacatgcaggtatgcgttccttccacgccggctcaggtttatcatatgttaagacgtcaggccttgcgcggtatgcg

  gcgcccgttggtcgtgatgtccccgaaaagtt

  SEQ ID NO: 9. Sequence of Plasmid pDvQ-GFP containing a sequence encoding the

  green fluorescent protein cloned into the pDvQ vector

  cgcgttgctggcgtttttccacaggctccgcccccctgacgagcatcacaaaaatcgacgctcaagtcagaggtggc

  gaaacccgacaggactataaagataccaggcgtttccccctggaagctccctcgtgcgctctcctgttccgaccctg

  ccgcttaccggatacctgtccgcctttctcccttcgggaagcgtggcgctttctcatagctcacgctgtaggtatct

  cagttcggtgtaggtcgttcgctccaagctgggctgtgtgcacgaaccccccgttcagcccgaccgctgcgccttat

  ccggtaactatcgtcttgagtccaacccggtaagacacgacttatcgccactggcagcagccactggtaacaggatt

  agcagagcgaggtatgtaggcggtgctacagagttcttgaagtggtggcctaactacggctacactagaagaacagt

  atttggtatctgcgctctgctgaagccagttaccttcggaaaaagagttggtagctcttgatccggcaaacaaacca

  ccgctggtagcggtggtttttttgtttgcaagcagcagattacgcgcagaaaaaaaggatctcaagaagatcctttg

  atcttttctacggggtctgacgctcagtggaacgaaaactcacgttaagggattttggtcatgagattatcaaaaag

  gatcttcacctagatccttttaaattaaaaatgaagttttaaatcaatctaaagtatatatgagtaaacttggtctg

  acagctcgaggtaggcctgataagacgcgcaagcgtcgcatcaggcaaccagtgccggatgcggcgtgaacgcctta

  tccggcctacaagtcattacccgtaggcctgataagcgcagcgcatcaggcgtaacaaagaaatgcaggaaatcttt

  aaaaactgcccctgacactaagacagtttttaaaggttccttcgcgagccactacgtagacaagagctcgcaagtga

  accccggcacgcacatcactgtgcgtggtagtatccacggcgaagtaagcataaaaaagatgcttaagggatcacgA

  ATGcagaacagcgctttgaaagcctggttggactcttcttacctctctggcgcaaaccagagctggatagaacagct

  ctatgaaGATttcttaaccgatcctgactcggttgacgctaactggcgttcgacgttccagcagttacctggtacgg

  gagtcaaaccggatcaattccactctcaaacgcgtgaatatttccgccgcctggcgaaagacgcttcacgttactct

  tcaacgatctccgaccctgacaccaatgtgaagcaggttaaagtcctgcagctcattaacgcataccgcttccgtgg

  tcaccagcatgcgaatctcgatccgctgggactgtggcagcaagataaagtggccgatctggatccgtctttccacg

  atctgaccgaagcagacttccaggagACTttcaacgtcggttcatttgccagcggcaaagaaaccatgaaactcggc

  gagctgctggaagccctcaagcaaacctactgcggcccgattggtgccgagtatatgcacattaccagcaccgaaga

  aaaacgctggatccaacagcgtatcgagtctggtcgcgcgactttcaatagcgaagagaaaaaacgcttcttaagcg

  aactgaccgccgctgaaggtcttgaacgttacctcggcgcaaaattccctggcgcaaaacgcttctcgctggaaggc

  ggtgacgcgttaatcccgatgcttaaagagatgatccgccacgctggcaacagcggcacccgcgaagtggttctcgg

  gatggcgcaccgtggtcgtctgaacgtgctggtgaacgtgctgggtaaaaaaccgcaagacttgttcgacgagttcg

  ccggtaaacataaagaacacctcggcacgggtgacgtgaaataccacatgggcttctcgtctgacttccagaccgat

  ggcggcctggtgcacctggcgctggcgtttaacccgtctcaccttgagattgtaagcccggtagttatcggttctgt

  tcgtgcccgtctggacagacttgatgagccgagcagcaacaaagtgctgccaatcaccatccacggtgacgccgcag

  tgaccgggcagggcgtggttcaggaaaccctgaacatgtcgaaagcgcgtggttatgaagttggcggtacggtacgt

  atcgttatcaacaaccaggttggtttcaccacctctaatccgctggatgcccgttctacgccgtactgtactgatat

  cggtaagatggttcaggccccgattttccacgttaacgcggacgatccggaagccgttgcctttgtgacccgtctgg

  cgctcgatttccgtaacacctttaaacgtgatGTTttcatcgacctggtgtgctaccgccgtcacggccacaacgaa

  gccgacgagccgagcgcaacccagccgctgatgtatcagaaaatcaaaaaacatccgacaccgcgcaaaatctacgc

  tgacaagctggagcaggaaaaagtggcgacgctggaagatgccaccgagatggttaacctgtaccgcgatgcgctgg

  atgctggcgattgcgtagtggcagagtggcgtccgatgaacatgcactctttcacctggtcgccgtacctcaaccac

  gaatgggacgaagagtacccgaacaaagttgagatgaagcgcctgcaggagctggcgaaacgcatcagcacggtgcc

  ggaagcagttgaaatgcagtctcgcgttgccaagatttatggcgatcgccaggcgatggctgccggtgagaaactgt

  tcgactggggcggtgcggaaaacctcgcttacgccacgctggttgatgaaggcattccggttcgcctgtcgggtGAG

  gactccggtcgcggtaccttcttccaccgccacgcggtgatccacaaccagtctaacggttccacttacacgccgct

  gcaacatatccataacgggcagggcgcgttccgtgtctgggactccgtactgtctgaagaagcagtgctggcgtttg

  aatatggttatgccaccgcagaaccacgcactctgaccatctgggaagcgcagttcggtgacttcgccaacggtgcg

  caggtggttatcgaccagttcatctcctctggcgaacagaaatggggccggatgtgtggtctggtgatgttgctgcc

  gcacggttacgaagggcaggggccggagcactcctccgcgcgtctggaacgttatctgcaactttgtgctgagcaaa

  acatgcaggtttgcgtaccgtctaccccggcacaggtttaccacatgctgcgtcgtcaggcgctgcgcgggatgcgt

  cgtccgctggtcgtgatgtcgccgaaatccctgctgcgtcatccgctggcggtttccagcctcgaagaactggcgaa

  cggcaccttcctgccagccatcggtgaaatcgacgagcttgatccgaagggcgtgaagcgcgtagtgatgtgttctg

  gtaaggtttattacgacctgctggaacagcgtcgtaagaacaatcaacacgatgtcgccattgtgcgtatcgagcaa

  ctctacccgttcccgcataaagcgatgcaggaagtgttgcagcagtttgctcacgtcaaggattttgtctggtgcca

  ggaagagccgctcaaccagggcgcatggtactgcagccagcatcatttccgtgaagtgattccgtttggggcttctc

  tgcgttatgcaggccgcccggcctccgcctctccggcggtagggtatatgtccgttcaccagaaacagcaacaagat

  ctggttaatgacgcgctgaacgtcgaataaataaaggatacacaatgagtagcgtagatattctggtccctgacctg

  cctgaatccgtagccgatgccaccgtcgcaacctggcataaaaaacccggcgacgcagtcgtacgtgatgaagtgct

  ggtagaaatcgaaactgacaaagtggtactggaagtaccggcatcagcagacggcattctggatgcggttctggaag

  atgaaggtacaacggtaacgtctcgtcagatccttggtcgcctgcgtgaaggcaacagcgccggtaaagaaaccagc

  gccaaatctgaagagaaagcgtccactccggcgcaacgccagcaggcgtctctggaagagcaaaacaacgatgcgtt

  aagcccggcgatccgtcgcctgctggctgaacacaatctcgacgccagcgccattaaaggcaccggtgtgggtggtc

  gtctgactcgtgaagatgtggaaaaacatctggcgaaagccccggcgaaagagtctgctccggcagcggctgctccg

  gcggcgcaaccggctctggctgcacgtagtgaaaaacgtgtcccgatgactcgcctgcgtaagcgtgtggcagagcg

  tctgctggaagcgaaaaactccaccgccatgctgaccacgttcaacgaagtcaacatgaagccgattatggatctgc

  gtaagcagtacggtgaagcgtttgaaaaacgccacggcatccgtctgggctttatgtccttctacgtgaaagcggtg

  gttgaagccctgaaacgttacccggaagtgaacgcttctatcgacggcgatgacgtggtttaccacaactatttcga

  cgtcagcatggcggtttctacgccgcgcggcctggtgacgccggttctgcgtgatgtcgataccctcggcatggcag

  acatcgagaagaaaatcaaagagctggcagtcaaaggccgtgacggcaagctgaccgttgaagatctgaccggtggt

  aacttcaccatcaccaacggtggtgtgttcggttccctgatgtctacgccgatcatcaacccgccgcagagcgcaat

  tctgggtatgcacgctatcaaagatcgtccgatggcggtgaatggtcaggttgagatcctgccgatgatgtacctgg

  cgctgtcctacgatcaccgtctgatcgatggtcgcgaatccgtgggcttcctggtaacgatcaaagagttgctggaa

  gatccgacgcgtctgctgctggacgtgtagtagtttaagtttcacctgcactgtagaccggataaggcattatcgcc

  ttctccggcaattgaagcctgatgcgacgctgacgcgtcttatcaggcctacgggaccaccaatgtaggtcggataa

  ggcgcaagcgccgcatccgacaagcgatgcctgatgtgacgtttaacgtgtcttatcaggcctacgggtgaccgaca

  atgcccggaagcgatacgaaatattcGGTCTACGGTTTAAAAGATAACGATTACTGAAGGATGGACAGAACACatga

  acttacatgaatatcaggcaaaacaactttttgcccgctatggcttaccagcaccggtgggttatgcctgtactact

  ccgcgcgaagcagaagaagccgcttcaaaaatcggtgccggtccgtgggtagtgaaatgtcaggttcacgctggtgg

  ccgcggtaaagcgggcggtgtgaaagttgtaaacagcaaaGAGgacatccgtgcttttgcagaaaactggctgggca

  agcgtctggtaacgtatcaaacagatgccaatggccaaccggttaaccagattctggttgaagcagcgaccgatatc

  gctaaagagctgtatctcggtgccgttgttgaccgtagttcccgtcgtgtggtctttatggcctccaccgaaggcgg

  cgtggaaatcgaaaaagtggcggaagaaactccgcacctgatccataaagttgcgcttgatccgctgactggcccga

  tgccgtatcagggacgcgagctggcgttcaaactgggtctggaaggtaaactggttcagcagttcaccaaaatcttc

  atgggcctggcgaccattttcctggagcgcgacctggcgttgatcgaaatcaacccgctggtcatcaccaaacaggg

  cgatctgatttgcctcgacggcaaactgggcgctgacggcaacgcactgttccgccagcctgatctgcgcgaaatgc

  gtgaccagtcgcaggaagatccgcgtgaagcacaggctgcacagtgggaactgaactacgttgcgctggacggtaac

  atcggttgtatggttaacggcgcaggtctggcgatgggtacgatggacatcgttaaactgcacggcggcgaaccggc

  taacttccttgacgttggcggcggcgcaaccaaagaacgtgtaaccgaagcgttcaaaatcatcctctctgacgaca

  aagtgaaagccgttctggttaacatcttcggcggtatcgttcgttgcgacctgatcgctgacggtatcatcggcgcg

  gtagcagaagtgggtgttaacgtaccggtcgtggtacgtctggaaggtaacaacgccgaactcggcgcgaagaaact

  ggctgacagcggcctgaatattattgcagcaaaaggtctgacggatgcagctcagcaggttgttgccgcagtggagg

  ggaaataatgtccattttaatcgataaaaacaccaaggttatctgccagggctttaccggtagccaggggactttcc

  actcagaacaggccattgcatacggcactaaaatggttggcggcgtaaccccaggtaaaggcggcaccacccacctc

  ggcctgccggtgttcaacaccgtgcgtgaagccgttgctgccactggcgctaccgcttctgttatctacgtaccagc

  accgttctgcaaagactccattctggaagccatcgacgcaggcatcaaactgattatcaccatcactgaaggcatcc

  cgacgctggatatgctgaccgtgaaagtgaagctggatgaagcaggcgttcgtatgatcggcccgaactgcccaggc

  gttatcactccgggtgaatgcaaaatcggtatccagcctggtcacattcacaaaccgggtaaagtgggtatcgtttc

  ccgttccggtacactgacctatgaagcggttaaacagaccacggattacggtttcggtcagtcgacctgtgtcggta

  tcggcggtgacccgatcccgggctctaactttatcgacattctcgaaatgttcgaaaaagatccgcagaccgaagcg

  atcgtgatgatcggtgagatcggcggtagcgctgaagaagaagcagctgcgtacatcaaagagcacgttaccaagcc

  agttgtgggttacatcgctggtgtgactgcgccgaaaggcaaacgtatgggccacgcgggtgccatcattgccggtg

  ggaaagggactgcggatgagaaattcgctgctctggaagccgcaggcgtgaaaaccgttcgcagcctggcggatatc

  ggtgaagcactgaaaactgttctgaaataaaggtccaggcatcaaataaaacgaaaggctcagtcgaaagactgggc

  ctttcgttttatctgttgtttgtcggtgaacgctctctactagagtcacactggctcaccttcgggtgggcctttct

  gcgtttatatcccgtcaagtcagcgtaatgctctgccagtgttacaaccaattaaccaattctgattagaaaaactc

  atcgagcatcaaatgaaactgcaatttattcatatcaggattatcaataccatatttttgaaaaagccgtttctgta

  atgaaggagaaaactcaccgaggcagttccataggatggcaagatcctggtatcggtctgcgattccgactcgtcca

  acatcaatacaacctattaatttcccctcgtcaaaaataaggttatcaagtgagaaatcaccatgagtgacgactga

  atccggtgagaatggcaaaagcttatgcatttctttccagacttgttcaacaggccagccattacgctcgtcatcaa

  aatcactcgcatcaaccaaaccgttattcattcgtgattgcgcctgagcgagacgaaatacgcgatcgctgttaaaa

  ggacaattacaaacaggaatcgaatgcaaccggcgcaggaacactgccagcgcatcaacaatattttcacctgaatc

  aggatattcttctaatacctggaatgctgttttcccggggatcgcagtggtgagtaaccatgcatcatcaggagtac

  ggataaaatgcttgatggtcggaagaggcataaattccgtcagccagtttagtctgaccatctcatctgtaacatca

  ttggcaacgctacctttgccatgtttcagaaacaactctggcgcatcgggcttcccatacaatcgatagattgtcgc

  acctgattgcccgacattatcgcgagcccatttatacccatataaatcagcatccatgttggaatttaatcgcggcc

  tggagcaagacgtttcccgttgaatatggctcataacaccccttgtattactgtttatgtaagcagacagttttatt

  gttcatgatgatatatttttatcttgtgcaatgtaacatcagagattttgagacacaacgtggctttgttgaataaa

  tcgaacttttgctgagttgaaggatcagctcgagtgccacctgacgtctaagaaaccattattatcatgacattaac

  ctataaaaataggcgtatcacgaggcagaatttcagataaaaaaaatccttagctttcgctaaggatgatttctgga

  attcgcggccgcttctagagactagtggaagacatcgctggaaagtgaaacgtgatttcatgcgtcattttgaacat

  tttgtaaatcttatttaataatgtgtgcggcaattcacatttaatttatgaatgttttcttaacatcgcggcaactc

  aagaaacggcaggttcggatcttagctactagagaaagaggagaaatactagatgcgtaaaggcgaagagctgttca

  ctggtgtcgtccctattctggtggaactggatggtgatgtcaacggtcataagttttccgtgcgtggcgagggtgaa

  ggtgacgcaactaatggtaaactgacgctgaagttcatctgtactactggtaaactgccggttccttggccgactct

  ggtaacgacgctgacttatggtgttcagtgctttgctcgttatccggaccatatgaagcagcatgacttcttcaagt

  ccgccatgccggaaggctatgtgcaggaacgcacgatttcctttaaggatgacggcacgtacaaaacgcgtgcggaa

  gtgaaatttgaaggcgataccctggtaaaccgcattgagctgaaaggcattgactttaaagaggacggcaatatcct

  gggccataagctggaatacaattttaacagccacaatgtttacatcaccgccgataaacaaaaaaatggcattaaag

  cgaattttaaaattcgccacaacgtggaggatggcagcgtgcagctggctgatcactaccagcaaaacactccaatc

  ggtgatggtcctgttctgctgccagacaatcactatctgagcacgcaaagcgttctgtctaaagatccgaacgagaa

  acgcgatcatatggttctgctggagttcgtaaccgcagcgggcatcacgcatggtatggatgaactgtacaaatgac

  caggcatcaaataaaacgaaaggctcagtcgaaagactgggcctttcgttttatctgttgtttgtcggtgaacgctc

  tctactagagtcacactggctcaccttcgggtgggcctttctgcgtttatacgtgccatgtcttctactagtagcgg

  ccgctgcagtccggcaaaaaagggcaaggtgtcaccaccctgccctttttctttaaaaccgaaaagattacttcgcg

  ttatgcaggcttcctcgctcactgactcgctgcgctcggtcgttcggctgcggcgagcggtatcagctcactcaaag

  gcggtaatacggttatccacagaatcaggggataacgcaggaaagaacatgtgagcaaaaggccagcaaaaggccag

  gaaccgtaaaaaggc

  SEQ ID NO: 10. Sequence of Plasmid pDvK-SucBC, used for testing plasmid retention

  in nonselective media

  GGATGGACAGAACACATGAACTTACATGAATATCAGGCAAAACAACTTTTTGCCCGCTATGGCTTACCAGCACCGGT

  GGGTTATGCCTGTACTACTCCGCGCGAAGCAGAAGAAGCCGCTTCAAAAATCGGTGCCGGTCCGTGGGTAGTGAAAT

  GTCAGGTTCACGCTGGTGGCCGCGGTAAAGCGGGCGGTGTGAAAGTTGTAAACAGCAAAGAGGACATCCGTGCTTTT

  GCAGAAAACTGGCTGGGCAAGCGTCTGGTAACGTATCAAACAGATGCCAATGGCCAACCGGTTAACCAGATTCTGGT

  TGAAGCAGCGACCGATATCGCTAAAGAGCTGTATCTCGGTGCCGTTGTTGACCGTAGTTCCCGTCGTGTGGTCTTTA

  TGGCCTCCACCGAAGGCGGCGTGGAAATCGAAAAAGTGGCGGAAGAAACTCCGCACCTGATCCATAAAGTTGCGCTT

  GATCCGCTGACTGGCCCGATGCCGTATCAGGGACGCGAGCTGGCGTTCAAACTGGGTCTGGAAGGTAAACTGGTTCA

  GCAGTTCACCAAAATCTTCATGGGCCTGGCGACCATTTTCCTGGAGCGCGACCTGGCGTTGATCGAAATCAACCCGC

  TGGTCATCACCAAACAGGGCGATCTGATTTGCCTCGACGGCAAACTGGGCGCTGACGGCAACGCACTGTTCCGCCAG

  CCTGATCTGCGCGAAATGCGTGACCAGTCGCAGGAAGATCCGCGTGAAGCACAGGCTGCACAGTGGGAACTGAACTA

  CGTTGCGCTGGACGGTAACATCGGTTGTATGGTTAACGGCGCAGGTCTGGCGATGGGTACGATGGACATCGTTAAAC

  TGCACGGCGGCGAACCGGCTAACTTCCTTGACGTTGGCGGCGGCGCAACCAAAGAACGTGTAACCGAAGCGTTCAAA

  ATCATCCTCTCTGACGACAAAGTGAAAGCCGTTCTGGTTAACATCTTCGGCGGTATCGTTCGTTGCGACCTGATCGC

  TGACGGTATCATCGGCGCGGTAGCAGAAGTGGGTGTTAACGTACCGGTCGTGGTACGTCTGGAAGGTAACAACGCCG

  AACTCGGCGCGAAGAAACTGGCTGACAGCGGCCTGAATATTATTGCAGCAAAAGGTCTGACGGATGCAGCTCAGCAG

  GTTGTTGCCGCAGTGGAGGGGAAATAAAGGTCCAGGCATCAAATAAAACGAAAGGCTCAGTCGAAAGACTGGGCCTT

  TCGTTTTATCTGTTGTTTGTCGGTGAACGCTCTCTACTAGAGTCACACTGGCTCACCTTCGGGTGGGCCTTTCTGCG

  TTTATAGCTTATGTCTTCTACTAGTAGCGGCCGCTGCAGTCCGGCAAAAAAGGGCAAGGTGTCACCACCCTGCCCTT

  TTTCTTTAAAACCGAAAAGATTACTTCGCGTTATGCAGGCTTCCTCGCTCACTGACTCGCTGCGCTCGGTCGTTCGG

  CTGCGGCGAGCGGTATCAGCTCACTCAAAGGCGGTAATACGGTTATCCACAGAATCAGGGGATAACGCAGGAAAGAA

  CATGTGAGCAAAAGGCCAGCAAAAGGCCAGGAACCGTAAAAAGGCCGCGTTGCTGGCGTTTTTCCACAGGCTCCGCC

  CCCCTGACGAGCATCACAAAAATCGACGCTCAAGTCAGAGGTGGCGAAACCCGACAGGACTATAAAGATACCAGGCG

  TTTCCCCCTGGAAGCTCCCTCGTGCGCTCTCCTGTTCCGACCCTGCCGCTTACCGGATACCTGTCCGCCTTTCTCCC

  TTCGGGAAGCGTGGCGCTTTCTCATAGCTCACGCTGTAGGTATCTCAGTTCGGTGTAGGTCGTTCGCTCCAAGCTGG

  GCTGTGTGCACGAACCCCCCGTTCAGCCCGACCGCTGCGCCTTATCCGGTAACTATCGTCTTGAGTCCAACCCGGTA

  AGACACGACTTATCGCCACTGGCAGCAGCCACTGGTAACAGGATTAGCAGAGCGAGGTATGTAGGCGGTGCTACAGA

  GTTCTTGAAGTGGTGGCCTAACTACGGCTACACTAGAAGAACAGTATTTGGTATCTGCGCTCTGCTGAAGCCAGTTA

  CCTTCGGAAAAAGAGTTGGTAGCTCTTGATCCGGCAAACAAACCACCGCTGGTAGCGGTGGTTTTTTTGTTTGCAAG

  CAGCAGATTACGCGCAGAAAAAAAGGATCTCAAGAAGATCCTTTGATCTTTTCTACGGGGTCTGACGCTCAGTGGAA

  CGAAAACTCACGTTAAGGGATTTTGGTCATGAGATTATCAAAAAGGATCTTCACCTAGATCCTTTTAAATTAAAAAT

  GAAGTTTTAAATCAATCTAAAGTATATATGAGTAAACTTGGTCTGACAGCTCGAGTCCCGTCAAGTCAGCGTAATGC

  TCTGCCAGTGTTACAACCAATTAACCAATTCTGATTAGAAAAACTCATCGAGCATCAAATGAAACTGCAATTTATTC

  ATATCAGGATTATCAATACCATATTTTTGAAAAAGCCGTTTCTGTAATGAAGGAGAAAACTCACCGAGGCAGTTCCA

  TAGGATGGCAAGATCCTGGTATCGGTCTGCGATTCCGACTCGTCCAACATCAATACAACCTATTAATTTCCCCTCGT

  CAAAAATAAGGTTATCAAGTGAGAAATCACCATGAGTGACGACTGAATCCGGTGAGAATGGCAAAAGCTTATGCATT

  TCTTTCCAGACTTGTTCAACAGGCCAGCCATTACGCTCGTCATCAAAATCACTCGCATCAACCAAACCGTTATTCAT

  TCGTGATTGCGCCTGAGCGAGACGAAATACGCGATCGCTGTTAAAAGGACAATTACAAACAGGAATCGAATGCAACC

  GGCGCAGGAACACTGCCAGCGCATCAACAATATTTTCACCTGAATCAGGATATTCTTCTAATACCTGGAATGCTGTT

  TTCCCGGGGATCGCAGTGGTGAGTAACCATGCATCATCAGGAGTACGGATAAAATGCTTGATGGTCGGAAGAGGCAT

  AAATTCCGTCAGCCAGTTTAGTCTGACCATCTCATCTGTAACATCATTGGCAACGCTACCTTTGCCATGTTTCAGAA

  ACAACTCTGGCGCATCGGGCTTCCCATACAATCGATAGATTGTCGCACCTGATTGCCCGACATTATCGCGAGCCCAT

  TTATACCCATATAAATCAGCATCCATGTTGGAATTTAATCGCGGCCTGGAGCAAGACGTTTCCCGTTGAATATGGCT

  CATAACACCCCTTGTATTACTGTTTATGTAAGCAGACAGTTTTATTGTTCATGATGATATATTTTTATCTTGTGCAA

  TGTAACATCAGAGATTTTGAGACACAACGTGGCTTTGTTGAATAAATCGAACTTTTGCTGAGTTGAAGGATCAGCTC

  GAGTGCCACCTGACGTCTAAGAAACCATTATTATCATGACATTAACCTATAAAAATAGGCGTATCACGAGGCAGAAT

  TTCAGATAAAAAAAATCCTTAGCTTTCGCTAAGGATGATTTCTGGAATTCGCGGCCGCTTCTAGAGACTAGTGGAAG

  ACATGGAGTTTACGGCTAGCTCAGTCCTAGGTATAGTGCTAGCTACTTGTTAGAAAAGAGAAGCACGTAATGAGTAG

  CGTAGATATTCTGGTCCCTGACCTGCCTGAATCCGTAGCCGATGCCACCGTCGCAACCTGGCATAAAAAACCCGGCG

  ACGCAGTCGTACGTGATGAAGTGCTGGTAGAAATCGAAACTGACAAAGTGGTACTGGAAGTACCGGCATCAGCAGAC

  GGCATTCTGGATGCGGTTCTGGAAGATGAAGGTACAACGGTAACGTCTCGTCAGATCCTTGGTCGCCTGCGTGAAGG

  CAACAGCGCCGGTAAAGAAACCAGCGCCAAATCTGAAGAGAAAGCGTCCACTCCGGCGCAACGCCAGCAGGCGTCTC

  TGGAAGAGCAAAACAACGATGCGTTAAGCCCGGCGATCCGTCGCCTGCTGGCTGAACACAATCTCGACGCCAGCGCC

  ATTAAAGGCACCGGTGTGGGTGGTCGTCTGACTCGTGAAGATGTGGAAAAACATCTGGCGAAAGCCCCGGCGAAAGA

  GTCTGCTCCGGCAGCGGCTGCTCCGGCGGCGCAACCGGCTCTGGCTGCACGTAGTGAAAAACGTGTCCCGATGACTC

  GCCTGCGTAAGCGTGTGGCAGAGCGTCTGCTGGAAGCGAAAAACTCCACCGCCATGCTGACCACGTTCAACGAAGTC

  AACATGAAGCCGATTATGGATCTGCGTAAGCAGTACGGTGAAGCGTTTGAAAAACGCCACGGCATCCGTCTGGGCTT

  TATGTCCTTCTACGTGAAAGCGGTGGTTGAAGCCCTGAAACGTTACCCGGAAGTGAACGCTTCTATCGACGGCGATG

  ACGTGGTTTACCACAACTATTTCGACGTCAGCATGGCGGTTTCTACGCCGCGCGGCCTGGTGACGCCGGTTCTGCGT

  GATGTCGATACCCTCGGCATGGCAGACATCGAGAAGAAAATCAAAGAGCTGGCAGTCAAAGGCCGTGACGGCAAGCT

  GACCGTTGAAGATCTGACCGGTGGTAACTTCACCATCACCAACGGTGGTGTGTTCGGTTCCCTGATGTCTACGCCGA

  TCATCAACCCGCCGCAGAGCGCAATTCTGGGTATGCACGCTATCAAAGATCGTCCGATGGCGGTGAATGGTCAGGTT

  GAGATCCTGCCGATGATGTACCTGGCGCTGTCCTACGATCACCGTCTGATCGATGGTCGCGAATCCGTGGGCTTCCT

  GGTAACGATCAAAGAGTTGCTGGAAGATCCGACGCGTCTGCTGCTGGACGTGTAGTAGTTTAAGTTTCACCTGCACT

  GTAGACCGGATAAGGCATTATCGCCTTCTCCGGCAATTGAAGCCTGATGCGACGCTGACGCGTCTTATCAGGCCTAC

  GGGACCACCAATGTAGGTCGGATAAGGCGCAAGCGCCGCATCCGACAAGCGATGCCTGATGTGACGTTTAACGTGTC

  TTATCAGGCCTACGGGTGACCGACAATGCCCGGAAGCGATACGAAATATTCGGTCTACGGTTTAAAAGATAACGATT

  ACTGAA

Claims (37)

1. A transformed bacterial host cell containing:

i) an extrachromosomal DNA sequence encoding at least one protein of interest, the expression of which is regulated and operably associated with at least one extrachromosomal element; and,

ii) a DNA sequence encoding at least one necessary succinate pathway gene that has been removed from said bacterial host cell;

iii) where such sequences are complementary to a DNA sequence of interest contained in a plasmid; and,

iv) where both DNA sequences are positioned upstream or downstream of the ribosomal binding site of the DNA sequence.

2. The bacterial cell of claim 1, wherein said DNA sequence is foreign to said cell.

3. The bacterial cell of claim 1, wherein said extrachromosomal DNA sequence encodes more than one polypeptide of interest.

4. The bacterial cell of claim 1, wherein said extrachromosomal DNA sequence encodes more than one essential succinate pathway gene each of which is essential to the central metabolism of said cell.

5. The bacterial cell of claim 1, wherein said foreign DNA sequence is under the control of a promoter.

6. The bacterial cell of claim 1, wherein said extrachromosomal element is a plasmid.

7. A plasmid of claim 6, wherein the origin of replication is derived from pBR322, pMB1, ColE1, pSC101 or p15A.

8. A method of maintaining two or more plasmids in a transformed microbial host cell comprising the bacterial cell of claim 1, wherein each plasmid utilized contains at least one of the needed succinate pathway genes and collectively at least one of the plasmids contains a gene of interest capable of expressing a protein product where said transformed bacterial cell is in the presence of conditions sufficient to permit said cell to grow.

9. A process for producing a recombinant protein of interest in a transformed bacterial host, comprising:

a) introducing at least one recombinant plasmid into said bacterial host cell, wherein said recombinant plasmid comprises a cloned DNA sequence comprising all or part of a gene encoding an essential succinate pathway gene that is integral to the survival of the host cell and also encodes at least one gene of interest coding for a protein product;

b) selecting surviving colonies of the transformed host containing the recombinant plasmid; and,

c) using the surviving colonies for fermenting bacterial colonies to allow the expression of said protein product.

10. The protein product of claim 9, wherein the recombinant protein product additionally comprises an amino acid sequence that will optimize purification, isolation or tagging.

11. The bacterial cell of claim 9, wherein said essential gene is operably linked to a promoter which contains a DNA sequence of interest.

12. The bacterial cell of claim 11, wherein said promoter linked to said essential gene is inducible.

13. The bacterial cell of claim 12, wherein said inducible promoter is independent of any other inducible promoter controlling a foreign DNA sequence.

14. The bacterial cell of claim 1, wherein said DNA sequence ii) is inserted between the ribosomal binding site and the start codon of said DNA sequence i).

15. The bacterial cell of claim 1, wherein said DNA sequence i) and said DNA sequence ii) are transcriptionally coupled.

16. The bacterial cell of claim 15, wherein said cell is selected from a group comprising: a Escherichia coli cell; Corynebacterium spp., Vibrio spp.; Escherichia spp.; Enterobacter spp.; Citrobacter spp.; Erwinia spp.; Bacillus spp.; Pseudomonas spp.; Cyanobacteria spp.; Salmonella spp. and Klebsiella spp.

17. The host-vector system of claim 16, wherein said plasmid additionally contains a second gene of interest coding for a protein product.

18. The bacterial cell of claim 1, wherein said DNA sequence ii) is positioned upstream or downstream of the ribosomal binding site of the DNA sequence of i), upstream of a start codon of said marker gene and downstream of a promoter.

19. The bacterial cell of claim 18, wherein said marker gene is a marker gene that is essential to the central metabolism of said cell.

20. A double-stranded DNA plasmid which upon introduction into a microbial host cell renders the host cell capable of effecting the expression of a DNA encoding at least one desired foreign polypeptide and at least one gene integral in the cellular succinate pathway comprising the following:

a) DNA which includes at least one promoter of interest;

b) a first DNA sequence which encodes at least one polypeptide of interest;

c) a second DNA sequence which encodes at least one gene integral to the functionality of the cellular succinate pathway where such gene has been removed or rendered non-functional in the microbial host cell; and,

d) an initiation codon.

21. The double-stranded DNA plasmid of claim 20, further comprising a DNA sequence comprising an origin of replication from a bacterial plasmid capable of autonomous replication in the host cell and a DNA sequence which contains a gene associated with a protein product of interest which is expressed when the plasmid is present in the microbial host cell.

22. A recombinant host cell according to claim 21, wherein said first coding sequence encodes a polypeptide of interest.

23. A recombinant host cell according to claim 20, wherein expression of said at least one polypeptide of interest leads to the production of at least one protein of interest.

24. A recombinant host cell according to claim 16, wherein said enteric bacterium is a Bacillus cell.

25. A recombinant host cell according to claim 16, wherein said enteric bacterium is an Escherichia coli cell.

26. A recombinant host cell according to claim 16, wherein said enteric bacterium is a Corneybacterium cell.

27. The recombinant host cell according to claim 1, wherein the DNA sequence encoding at least one necessary succinate pathway gene that has been removed from the recombinant host cell is functionally removed via a deletion, a disruption or a mutation that reduces or eliminates the activity of one or more chromosomal genes encoding one or more succinate pathway genes.

28. The recombinant host cell according to claim 27, further comprising at least one plasmid containing at least one necessary gene of the succinate pathway operably linked to a promoter, said plasmid lacking an antibiotic resistance gene, wherein the plasmid is stably maintained in the isolated transformed microbial host cell when grown in the presence of diaminopimelic acid.

29. The recombinant host cell according to claim 28, wherein the growth conditions are aerobic or microaerobic.

30. The recombinant host cell according to claim 28, wherein the growth conditions are anaerobic.

31. The recombinant host cell according to claim 27, further comprising four plasmids each of which contains at least one different gene of the succinate pathway each of which is integral to the survival of the cell and each of which is operably linked to a promoter, each said plasmid lacking an antibiotic resistance gene, wherein the plasmids are stably maintained.

32. The recombinant host of claim 27, further comprising a cell with a quadruple sucABCD deletion, wherein each of the native succinate genes removed are contained in at least one of the plasmids

33. The recombinant host of claim 32, wherein the first plasmid encodes the DNA sequence of sucAD and the second plasmid encodes the DNA sequence of sucBC.

34. The recombinant host of claim 32, wherein the first plasmid encodes the DNA sequence of sucAC and the second plasmid encodes the polypeptide of interest and has the DNA sequence of sucBD.

35. (canceled)

36. The recombinant host cell of claim 33, further comprising each of the two said plasmids contain the DNA sequence encoding a protein of interest.

37. The recombinant host cell of claim 34, further comprising each of the two said plasmids contain the DNA sequence encoding a protein of interest.

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