Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
  • C12N9/0004—Oxidoreductases (1.)
  • C12N9/0012—Oxidoreductases (1.) acting on nitrogen containing compounds as donors (1.4, 1.5, 1.6, 1.7)
  • C12N9/0044—Oxidoreductases (1.) acting on nitrogen containing compounds as donors (1.4, 1.5, 1.6, 1.7) acting on other nitrogen compounds as donors (1.7)
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23K—FODDER
  • A23K10/00—Animal feeding-stuffs
  • A23K10/10—Animal feeding-stuffs obtained by microbiological or biochemical processes
  • A23K10/12—Animal feeding-stuffs obtained by microbiological or biochemical processes by fermentation of natural products, e.g. of vegetable material, animal waste material or biomass
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23K—FODDER
  • A23K20/00—Accessory food factors for animal feeding-stuffs
  • A23K20/10—Organic substances
  • A23K20/142—Amino acids; Derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
  • C07K14/195—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria
  • C07K14/34—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria from Corynebacterium (G)
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P13/00—Preparation of nitrogen-containing organic compounds
  • C12P13/04—Alpha- or beta- amino acids
  • C12P13/12—Methionine; Cysteine; Cystine

Definitions

• the invention provides nucleotide sequences from coryneform bacteria which code for the etF gene and a process for the fermentative preparation of amino acids, in particular L- methionine, using bacteria in which the metF gene is enhanced.
• L-Amino acids in particular L-methionine, are used in human medicine and in the pharmaceuticals industry, in the foodstuffs industry and very particularly in animal nutrition.
• amino acids are prepared by fermentation from strains of coryneform bacteria, in particular Corynebacterium glutamicum. Because of their great importance, work is constantly being undertaken to improve the preparation processes. Improvements to the process can relate to fermentation measures, such as, for example, stirring and supply of oxygen, or the composition of the nutrient media, such as, for example, the sugar concentration during the fermentation, or the working up to the product form by, for example, ion exchange chromatography, or the intrinsic output properties of the microorganism itself.
• fermentation measures such as, for example, stirring and supply of oxygen
• the composition of the nutrient media such as, for example, the sugar concentration during the fermentation
• the working up to the product form by, for example, ion exchange chromatography or the intrinsic output properties of the microorganism itself.
• Strains which are resistant to antimetabolites such as e.g. the methionine analogue ⁇ - methyl-methionine, ethionine, norleucine, N- acetylnorleucine, S-trifluoromethylhomocysteine, 2-amino-5- heprenoitic acid, seleno-methionine, ethionine- sulfoximine, methoxine, 1-aminocyclopentane-carboxylic acid, or are auxotrophic for metabolites of regulatory importance and produce amino acid, such as e.g. - methionine, are obtained in this manner.
• antimetabolites such as e.g. the methionine analogue ⁇ - methyl-methionine, ethionine, norleucine, N- acetylnorleucine, S-trifluoromethylhomocysteine, 2-amino-5- heprenoitic acid, sel
• the inventors had the object of providing new measures for • improved fermentative preparation of amino acids, in particular L-methionine.
• the invention provides an isolated polynucleotide from coryneform bacteria, comprising a polynucleotide sequence which codes for the metF gene, chosen from the group consisting of
• polynucleotide which is identical to the extent of at least 70% to a polynucleotide which codes for a polypeptide which comprises the amino acid sequence of SEQ ID.No. 2,
• polynucleotide which codes for a polypeptide which comprises an amino acid sequence which is identical to the extent of at least 70% to the amino acid sequence of SEQ ID No. 2,
• polynucleotide which is complementary to the polynucleotides of a) or b) , and d) polynucleotide comprising at least 15 successive nucleotides of the polynucleotide sequence of a), b) or c),
• polypeptide preferably having the activity of methylene tetrahydrofolate reductase.
• the invention also provides the above-mentioned polynucleotide, this preferably being a DNA which is capable of replication, comprising:
• the invention also provides
• a vector containing the polynucleotide according to the invention in particular a shuttle vector or plasmid vector, and
• the invention also provides polynucleotides which substantially comprise a polynucleotide sequence, which are obtainable by screening by means of hybridization of a corresponding gene library, which comprises the complete gene with the polynucleotide sequence corresponding to SEQ ID No. 1, with a probe which comprises the sequence of the polynucleotide mentioned, according to SEQ ID No. 1 or a fragment thereof, and isolation of the DNA sequence mentioned.
• Polynucleotides which comprise the sequences according to the invention are suitable as hybridization probes for RNA, cDNA and DNA, in order to isolate, in the full length, nucleic acids or polynucleotides or genes which code for methylene tetrahydrofolate reductase or to isolate those nucleic acids or polynucleotides or genes which have a high similarity of sequence to methylene tetrahydrofolate reductase.
• Polynucleotides which comprise the sequences according to the invention are furthermore suitable as primers with the aid of which DNA of genes which code for methylene tetrahydrofolate reductase can be prepared by the polymerase chain reaction (PCR) .
• PCR polymerase chain reaction
• Such oligonucleotides which serve as probes or primers comprise at least 30, preferably at least 20, very particularly preferably at least 15 successive nucleotides. Oligonucleotides which have a length of at least 40 or 50 nucleotides are also suitable. Oligonucleotides with a length of at least 100, 150, 200, 250 or 300 nucleotides are optionally also suitable.
• Polynucleotide in general relates to polyribonucleotides and polydeoxyribonucleotides, it being possible for these to be non-modified RNA or DNA or modified RNA or DNA.
• Polypeptides are understood as meaning peptides or proteins which comprise two or more amino acids bonded via peptide bonds.
• polypeptides according to the invention include a polypeptide according to SEQ ID No. 2, in particular those with the biological activity of methylene tetrahydrofolate reductase, and also those which are at least 70%, preferably at least 80% and in particular which are at least 90% to 95% identical to the polypeptide according to SEQ ID No. 2 and have the activity mentioned.
• the invention moreover provides a process for- the fermentative preparation of amino acids, in particular L- methionine, using coryneform bacteria which in particular already produce amino acids, and in which the nucleotide sequences which code for the metF gene are enhanced, in particular over-expressed.
• enhancement in this connection describes the increase in the intracellular activity of one or more enzymes in a microorganism which are coded by the corresponding DNA, for example by increasing the number of copies of the gene or genes, using a potent promoter or using a gene which codes for a corresponding enzyme having a high activity, and optionally combining these measures.
• the activity or concentration of the corresponding protein is in general increased by at least 10%, 25%, 50%, 75%, 100%, 150%, 200%, 300%, 400% or 500%, up to a maximum of 1000% or 2000%, based on the starting microorganism.
• the microorganisms which the present invention provides can prepare L-amino acids, in particular L-methionine, from glucose, sucrose, lactose, fructose, maltose, molasses, starch, cellulose or from glycerol and ethanol. They can be representatives of coryneform bacteria, in particular of the genus Corynebacterium. Of the genus Corynebacterium, there may be mentioned in particular the species
• Suitable strains of the genus Corynebacterium in particular of the species Corynebacterium glutamicum (C. glutamicum) , are in particular the known wild-type strains
• L-amino acid-producing mutants or strains prepared therefrom such as, for example, the L-methionine-producing strain
• E. coli Escherichia coli
• the setting up of gene libraries is described in generally known textbooks and handbooks. The textbook by Winnacker: Gene und Klone, Amsterdam Einf ⁇ hrung in die Gentechnologie (Verlag Chemie, Weinheim, Germany, 1990), or the handbook by Sambrook et al.: Molecular Cloning, A Laboratory Manual (Cold Spring Harbor Laboratory Press, 1989) may be mentioned as an example.
• a well-known gene library is that of- the E. coli K-12 strain W3110 set up in ⁇ vectors by Kohara et al. (Cell 50, 495 -508 (1987)).
• plasmids such as pBR322 (Bolivar, Life Sciences, 25, 807-818 (1979)) or pUC9 (Vieira et al., 1982, Gene, 19:259-268).
• Suitable hosts are, in particular, those E. coli strains which are restriction- and recombination- defective.
• An example of these is the strain DH5 ⁇ mcr, which has been described by Grant et al. (Proceedings of the National Academy of Sciences USA, 87 (1990) 4645-4649).
• the long DNA fragments cloned with the aid of cos ids can in turn be subcloned in the usual vectors suitable for sequencing and then sequenced, as is described e.g. by Sanger et al. (Proceedings of the National Academy of Sciences of the United States of America, 74:5463-5467, 1977) .
• the resulting DNA sequences can then be investigated with known algorithms or sequence analysis programs, such as e.g. that of Staden (Nucleic Acids Research 14, 217- 232(1986)), that of Marck (Nucleic Acids Research 16, 1829- 1836 (1988)) or the GCG program of Butler (Methods of Biochemical Analysis 39, 74-97 (1998)).
• the new DNA sequence of C. glutamicum which codes for the metF gene and which, as SEQ ID No. 1, is a constituent of the present invention has been found.
• the amino acid sequence of the corresponding protein has furthermore been derived from the present DNA sequence by the methods described above.
• the resulting amino acid sequence of the metF gene product is shown in SEQ ID No. 2.
• Coding DNA sequences which result from SEQ ID No. 1 by the degeneracy of the genetic code are also a constituent of the invention.
• DNA sequences which hybridize with SEQ ID No. 1 or parts of SEQ ID No. 1 are a constituent of the invention.
• Conservative amino acid exchanges such as e.g. exchange of glycine for alanine or of aspartic acid for glutamic acid in proteins, are furthermore known among experts as "sense mutations" which do not lead to a fundamental change in the activity of the protein, i.e. are of neutral function.
• DNA sequences which hybridize with SEQ ID No. 1 or parts of SEQ ID No. 1 are a constituent of the invention.
• DNA sequences which are prepared by the polymerase chain reaction (PCR) using primers which result from SEQ ID No. 1 are a constituent of the invention.
• PCR polymerase chain reaction
• Such oligonucleotides typically have a length of at least 15 nucleotides.
• PCR polymerase chain reaction
• coryneform bacteria produce amino acids, in particular L-methionine, in an improved manner after over-expression of the metF gene.
• the number of copies of the corresponding genes can be increased, or the promoter and regulation region or the ribosome binding site upstream of the structural gene can be mutated.
• Expression cassettes which are incorporated upstream of the structural gene act in the same way.
• inducible promoters it is additionally possible to increase the expression in the course of fermentative L-methionine production.
• the expression is likewise improved by measures to prolong the life of the m-RNA.
• the enzyme activity is also increased by preventing the degradation of the enzyme protein.
• the genes or gene constructs can either be present in plasmids with a varying number of copies, or can be integrated and amplified in the chromosome. Alternatively, an over- expression of the genes in question can furthermore be achieved by changing the composition of the media and the culture procedure.
• Suitable plasmids are those which are • replicated in coryneform bacteria.
• Numerous known plasmid vectors such as e.g. pZl (Menkel et al., Applied and Environmental Microbiology (1989) 64: 549-554), pEKExl (Eikmanns et al., Gene 102:93-98 (1991)) or pHS2-l (Sonnen et al., Gene 107:69-74 (1991)) are based on the cryptic plasmids pHM1519, pBLl or pGAl .
• plasmid vectors such as e.g. those based on pCG4 (US-A 4,489,160), or pNG2 (Serwold-Davis et al., FEMS Microbiology Letters 66, 119- 124 (1990)), or pAGl (US-A 5,158,891), can be used in the same manner.
• Plasmid vectors which are furthermore suitable are also those with the aid of which the process of gene amplification by integration into the chromosome can be used, as has been described, for example, by Reinscheid et al. (Applied and Environmental Microbiology 60, 126-132 (1994)) for duplication or amplification of the hom-thrB operon.
• the complete gene is cloned in a plasmid vector which can replicate in a host (typically E. coli) , but not in C. glutamicum.
• Possible vectors are, for example, pSUP301 (Simon et al., Bio/Technology 1, 784-791 (1983)), pKl ⁇ mob or pK19mob (Schafer et al., Gene 145, 69- 73 (1994)), pGEM-T (Promega corporation, Madison, WI, USA), PCR2.1-TOPO (Shuman (1994). Journal of Biological Chemistry 269:32678-84; US-A 5, 487, 993) , ⁇ CR®Blunt (Invitrogen,
• the plasmid vector which contains the gene to be amplified is then transferred into the desired strain of C. glutamicum by conjugation or transformation.
• the method of conjugation is described, for example, by Schafer et al. (Applied and Environmental Microbiology 60, 756-759 (1994)). Methods for transformation are described, for example, by Thierbach et al.
• amino acids in particular L-methionine
• amino acids in particular L- methionine
• amino acids in particular L-methionine
• metF gene for one or more genes chosen from the group consisting of
• the term "attenuation" in this connection describes the reduction or elimination of the intracellular activity of one or more enzymes (proteins) in a microorganism which are coded by the corresponding DNA, for example by using a weak promoter ' or using a gene or allele which codes for a corresponding enzyme with a low activity or inactivates the corresponding gene or enzyme (protein) , and optionally combining these measures.
• the activity or concentration of the corresponding protein is in general reduced to 0 to 50%, 0 to 25%, 0 to 10% or 0 to 5% of the activity or concentration of the wild-type protein.
• metF gene it may furthermore be advantageous, for the production of amino acids, in particular L-methionine, to eliminate undesirable side reactions, (Nakayama: “Breeding of Amino Acid Producing Micro-organisms", in: Overproduction of Microbial Products, Krumphanzl, Sikyta, Vanek (eds.), Academic Press, London, UK, 1982) .
• amino acids in particular L-methionine
• microorganisms prepared according to the invention can be cultured continuously or discontinuously in the batch process (batch culture) or in the fed batch (feed process) or repeated fed batch process (repetitive feed process) for the purpose of production of amino acids, in particular L- methionine.
• batch culture batch culture
• feed process fed batch
• repetitive feed process repetition feed process
• a summary of known culture methods is described in the textbook by Chmiel (Bioreatechnik 1. Einfiihrung in die Biovonstechnik (Gustav Fischer Verlag, Stuttgart, 1991) ) or in the textbook by Storhas (Bioreaktoren und periphere bamboo (Vieweg Verlag, Braunschweig/Wiesbaden, 1994) ) .
• the culture medium to be used must meet the requirements of the particular strains in a suitable manner. Descriptions of culture media for various microorganisms are contained in the handbook “Manual of Methods for General Bacteriology” of the American Society for Bacteriology (Washington D.C., USA, 1981).
• Sugars and carbohydrates such as e.g. glucose, sucrose, lactose, fructose, maltose, molasses, starch and cellulose, oils and fats, such as e.g. soya oil, sunflower oil, groundnut oil and coconut fat, fatty acids, such as e.g. palmitic acid, stearic acid and linoleic acid, alcohols, such as e.g. glycerol and ethanol, and organic acids, such as e.g. acetic acid, can be used as the source of carbon. These substance can be used individually or as a mixture.
• oils and fats such as e.g. soya oil, sunflower oil, groundnut oil and coconut fat
• fatty acids such as e.g. palmitic acid, stearic acid and linoleic acid
• alcohols such as e.g. glycerol and ethanol
• organic acids such as e.g. acetic acid
• Organic nitrogen-containing compounds such as peptones, yeast extract, meat extract, malt extract, corn steep liquor, soya bean flour and urea
• inorganic compounds such as ammonium sulfate, ammonium chloride, ammonium phosphate, ammonium carbonate and ammonium nitrate, can be used as the source of nitrogen.
• the sources of nitrogen can be used individually or as a mixture.
• Organic and inorganic sulfur-containing compounds such as, for example, sulfides, sulfites, sulfates and thiosulfates, can be used as a source of sulfur, in particular for the preparation of methionine.
• Phosphoric acid, potassium dihydrogen phosphate or dipotassium hydrogen phosphate or the corresponding sodium- containing salts can be used as the source of phosphorus.
• the culture medium must furthermore comprise salts of metals, such as e. g. magnesium sulfate or iron sulfate, which are necessary for growth.
• essential growth substances such as amino acids and vitamins, can be employed in addition to the above-mentioned substances.
• Suitable precursors can moreover be added to the culture medium.
• the starting substances mentioned can be added to the culture in the form of a single batch, or can be fed in during the culture in a suitable manner.
• Basic compounds such as sodium hydroxide, potassium hydroxide, ammonia or aqueous ammonia, or acid compounds, such as phosphoric acid or sulfuric acid, can be employed in a suitable manner to control the pH of the culture.
• Antifoams such as e.g. fatty acid polyglycol esters, can be employed to control the development of foam.
• Suitable substances having a selective action such as e.g. antibiotics, can be added to the medium to maintain the stability of plasmids.
• oxygen or oxygen-containing gas mixtures such as e.g. air, are introduced into the culture.
• the temperature of the culture is usually 20°C to 45°C, and preferably 25°C to 40°C. Culturing is continued until a maximum of the. desired product has formed. This target is usually reached within 10 hours to 160 hours.
• the fermentation broths obtained in this way in particular containing L-methionine, usually have a dry weight of 7.5 to 25 wt.% and contain L-methionine. It is furthermore also advantageous if the fermentation is conducted in a sugar- limited procedure at least at the end, but in particular over at least 30% of the duration of the fermentation. That is to say, the concentration of utilizable sugar in the fermentation medium is reduced to ⁇ 0 to 3 g/1 during this period.
• the fermentation broth prepared in this manner is then further processed.
• all or some of the biomass can be removed from the fermentation broth by separation methods, such as e.g. centrifugation, filtration, decanting or a combination thereof, or it can be left completely in this.
• This broth is then thickened or concentrated by known methods, such as e.g. with the aid of a rotary evaporator, thin film evaporator, falling film evaporator, by reverse osmosis, or by nanofiltration.
• This concentrated fermentation broth can then be worked up by methods of freeze drying, spray drying, spray granulation or by other processes to give a preferably free-flowing, finely divided powder.
• This free-flowing, finely divided powder can then in turn by converted by suitable compacting or granulating processes into a coarse-grained, readily free-flowing, storable and largely dust-free product.
• suitable compacting or granulating processes into a coarse-grained, readily free-flowing, storable and largely dust-free product.
• organic or inorganic auxiliary substances or carriers such as starch, gelatin, cellulose derivatives or similar substances, such as are conventionally used as binders, gelling agents or thickeners in foodstuffs or feedstuffs processing, or further substances, such as, for example, silicas, silicates or stearates.
• Free-flowing is understood as meaning powders which flow unimpeded out of the vessel with the opening of 5 mm (millimeters) of a series of glass outflow vessels with outflow openings of various sizes (Klein, Seifen, Ole, Fette, Wachse 94, 12 (1968)).
• finely divided means a powder with a predominant content (> 50 %) with a particle size of 20 to
• the product described above is suitable as a feedstuffs additive, i.e. feed additive, for animal nutrition.
• the L-methionine content of the animal feedstuffs additive is conventionally 1 wt.% to 80 wt.%, preferably 2 wt.% to 80 wt.%, particularly preferably 4 wt.% to 80 wt.%, and very particularly preferably 8 wt.% to.80 wt.%, based on the dry weight of the animal feedstuffs additive. Contents of 1 wt.% to 60 wt.%, 2 wt.% to 60 wt .
• the water content of the feedstuffs additive is conventionally up to 5 wt.%, preferably up to 4 wt.%, and particularly preferably less than 2 wt.%.
• the invention accordingly also provides a process for the preparation of an L-methionine-containing animal feedstuffs additive from fermentation broths, which comprises the steps
• auxiliary substances chosen from the group consisting of silicas, silicates, stearates, grits and bran to the substances obtained according to a) to d) for stabilization and, to increase the storability; or
• L-methionine can be carried out by ion exchange chromatography with subsequent ninhydrin derivation, as described by Spackman et al. (Analytical Chemistry, 30, (1958), 1190).
• the process according to the invention is used for the fermentative preparation of amino acids, in particular L-methionine.
• Example 1 The present invention is explained in more detail in the following with the aid of embodiment examples .
• Example 1 The present invention is explained in more detail in the following with the aid of embodiment examples .
• the cosmid DNA was then cleaved with the restriction enzyme BamHI (Amersham Pharmacia, Freiburg, Germany, Product Description BamHI, Code no. 27-0868-04) .
• the cosmid DNA treated in this manner was mixed with the treated ATCC13032 DNA and the batch was treated with T4 DNA ligase (Amersham Pharmacia, Freiburg, Germany, Product Description T4-DNA- Ligase, Code no.27-0870-04) .
• the ligation mixture was then packed in phages with the aid of Gigapack II XL Packing Extract (Stratagene, La Jolla, USA, Product Description Gigapack II XL Packing Extract, Code no. 200217) .
• the plasmid preparation of the recombinant clones was carried out with Biorobot 9600 (Product No. 900200, Qiagen, Hilden, Germany) .
• the sequencing was carried out by the dideoxy chain termination method of Sanger et al. (1977, Proceedings of the National Academy of Sciences U.S.A., 74:5463-5467) with modifications according to Zimmermann et al. (1990, Nucleic Acids Research, 18:1067).
• the "RR dRhodamin Terminator Cycle Sequencing Kit” from PE Applied Biosystems Product No. 403044, Rothstadt, Germany) was used.
• the raw sequence data obtained were then processed using the Staden program package (1986, Nucleic Acids Research, 14:217-231) version 97-0.
• the individual sequences of the pZerol derivatives were assembled to a continuous contig.
• the computer-assisted coding region analysis was prepared with the XNIP program (Staden, 1986, Nucleic Acids Research, 14:217-231).
• the resulting nucleotide sequence is shown in SEQ ID No. 1. Analysis of the nucleotide sequence showed an open reading frame of 1046 base pairs, which was called the metF gene. The metF gene codes for a protein of 349 amino acids.
• metF-EVP5 metF-EVP5: . .
• the primers shown were synthesized by MWG-Biotech AG.
• PCR reaction was carried out by the standard PCR method of Innis et al. (PCR protocols. A guide to methods and applications, 1990, Academic Press) with Pwo-Polymerase from Roche Diagnostics GmbH (Mannheim, Germany) .
• the primers allow amplification of a DNA fragment 792 bp in size, which carries the complete metF gene, which is suitable for expression.
• the primer metF-EVP5 contains the sequence for the cleavage site of the restriction endonuclease BamHI and the primer metF-EVP3 the cleavage site of the restriction endonuclease Xhol, which are marked by underlining in the nucleotide sequence shown above.
• the metF fragment 792 bp in size was cleaved with the restriction endonucleases BamHI and Xhol.
• the batch was separated by gel electrophoresis and the metF fragment was then isolated from the agarose gel with the QiaExII Gel Extraction Kit (Product No. 20021, Qiagen, Hilden, Germany) .
• the E. coli - C. glutamicum shuttle expression vector pZ8-l (EP 0 375 889) was used as the base vector for the expression.
• DNA of the plasmid pZ8-l was cleaved completely with the restriction enzymes BamHI and Sail and then dephosphorylated with shrimp alkaline phosphatase (Roche Diagnostics GmbH, Mannheim, Germany, Product Description SAP, Product No. 1758250) .
• the metF fragment isolated from the agarose gel in example 3.1 and cleaved with the restriction endonucleases BamHI and Xhol was mixed with the vector pZ8-l prepared in this way and the batch was treated with T4 DNA ligase (Amersham Pharmacia, Freiburg, Germany, Product Description T4-DNA- Ligase, Code no.27-0870-04) . . .
• the ligation batch was transformed in the E. coli strain DH5 ⁇ mcr (Hanahan, In: DNA cloning. A Practical Approach. Vol. I. IRL-Press, Oxford, Washington DC, USA) . Selection of plasmid-carrying cells was made by plating out the transformation batch on LB agar (Lennox, 1955, Virology, 1:190) with 50 mg/1 kanamycin. After incubation overnight at 37°C, recombinant individual clones were selected. Plasmid DNA was isolated from a transformant with the Qiaprep Spin Miniprep Kit (Product No. 27106, Qiagen, Hilden, Germany) in accordance with the manufacturer's instructions and checked by restriction cleavage. The resulting plasmid was called pCREmetF. 3.3 Preparation of the strain C. glutamicum ATCC13032/pCREmetF
• the vector pCREmetF obtained in example 3.2 was electroporated in the strain C. glutamicum ATCC13032 using the electroporation method described by Liebl et al. (FEMS Microbiology Letters, 53:299-303 (1989)). Selection of the plasmid-carrying cells took place on LBHIS agar comprising 18.5 g/1 brain-heart infusion broth, 0.5 M sorbitol, 5 g/1 Bacto-tryptone, 2.5 g/1 Bacto-yeast extract, 5 g/1 NaCl and 18 g/1 Bacto-agar, which had been supplemented with 25 mg/1 kanamycin. Incubation was carried out for 2 days at 33°C.
• Plasmid DNA was isolated from a transformant by conventional methods (Peters-Wendisch et al., 1998, Microbiology 144, 915-927) and checked by restriction cleavage. The resulting strain was called ATCC13032pCREmetF.
• the C. glutamicum strain ATCCl3032/pCREmetF obtained in example 3 was cultured in a nutrient medium suitable for the production of methionine and the methionine content in the culture supernatant was determined.
• the strain was first incubated on an agar plate with the corresponding antibiotic (brain-heart agar with kanamycin (25 mg/1) ) for 24 hours at 33°C.
• a preculture was seeded (10 ml medium in a 100 ml conical flask) .
• the medium MM was used as the medium for the preculture.
• Medium MM
• MOPS morpholinopropanesulfonic acid
• Vitamin B12 (sterile-filtered) 0.02 mg/1
• the CSL, MOPS and the salt solution were brought to pH 7 with aqueous ammonia and autoclaved.
• the sterile substrate and vitamin solutions were then added, as well as the CaC0 3 autoclaved in the dry state.
• Kanamycin (25 mg/1) was added to this.
• the preculture was incubated for 16 hours at 33°C at 240 rpm on a shaking machine.
• a main culture was seeded from this preculture such that the initial OD (660 nm) of the main culture was 0.1.
• Medium MM was also used for the main culture. Culturing is carried out in a 10 ml volume ⁇ n a 100 ml conical flask with baffles. Kanamycin (25 mg/1) was added. Culturing was carried out at 33°C and 80% atmospheric humidity.
• the OD was determined at a measurement wavelength of 660 nm with a Biomek 1000 (Beckmann Instruments GmbH, Kunststoff) .
• the amount of methionine formed was determined with an amino acid analyzer from Eppendorf- BioTronik (Hamburg, Germany) by ion exchange chromatography and post-column derivation with ninhydrin detection.
• Km Resistance gene for kanamycin
• metF metF gene of C. glutamicum
• Ser Arg lie Ala Arg Arg Leu Ala Lys Gin Pro Leu Thr Thr Leu Val 100 105 110 cac ctg ace ctg gtt aac cac act cgc gaa gag atg aag gca att ctt 682
• Ser Arg lie Ala Arg Arg Leu Ala Lys Gin Pro Leu Thr Thr Leu Val 100 105 110 His Leu Thr Leu Val Asn His Thr Arg Glu Glu Met Lys Ala lie Leu 115 120 125
• Phe Arg Glu Phe Asp Leu Gly lie Ala Ser Phe Pro Glu Gly His Phe 180 185 190 Arg Ala Lys Thr Leu Glu Glu Asp Thr Lys Tyr Thr Leu Ala Lys Leu 195 200 205

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• 2001
  • 2001-07-17 EP EP01967192A patent/EP1307477A2/de not_active Withdrawn
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