Summary of the invention
The present invention produces the inapparent technical problem of long-chain biatomic acid effect to solve existing bacterial strain, and the long-chain biatomic acid providing a kind of production efficiency high produces bacterial strain and its preparation method and application.
For this reason, the invention provides a kind of long-chain biatomic acid and produce bacterial strain, its Classification And Nomenclature is candidiasis Candida sp.TDTC002, described bacterial strain is preserved in China Committee for Culture Collection of Microorganisms's common micro-organisms center on March 18th, 2014, be called for short CGMCC, address is No. 3, Yard 1, BeiChen xi Road, Chaoyang District, Beijing City, Institute of Microorganism, Academia Sinica; Deposit number is: CGMCCNo.8927.
Preferably, the ester acyl coenzyme A synthase gene of candidiasis is knocked a copy.
Preferably, ester acyl coenzyme A synthetic enzyme base is allele C andidaA00308 and Candida01833, and its base sequence is as shown in the sequence 5 of sequence table and sequence 6.This gene be encode in this strain gene group this enzyme multiple genes in the most key one is produced for long-chain biatomic acid.
The present invention provides a kind of long-chain biatomic acid to produce the preparation method of bacterial strain simultaneously, and it comprises the steps: (1) prepares primer ACS-FRTF and ACS-FRTR; (2) prepare long-chain biatomic acid and produce bacterial strain competent cell; (3) primer in step (1) is used to carry out amplification clonNAT resistant gene, utilize the product of amplification to knock out one of CandidaA00308 and Candida01833 allelotrope in bacterial classification, described allelic base sequence is as shown in the sequence 5 of sequence table and sequence 6; (4) turn by pcr amplification, purifying, electricity, screen, identify, obtain long-chain biatomic acid and produce bacterial strain.
Preferably, in the present invention, long-chain biatomic acid produces the preparation method of bacterial strain, and the selection markers used in screening step is clonNAT resistance.
Preferably, long-chain biatomic acid produces the preparation method of bacterial strain, and the long-chain biatomic acid in step (2) produces bacterial strain candiyeast (Candida sp.) DC12.
The present invention provides long-chain biatomic acid to produce bacterial strain simultaneously and is producing the application in long-chain biatomic acid.Preferably, after fermentation ends, fermented liquid is heated to 70 ~ 80 DEG C; Again pH is adjusted to 9 ~ 9.5, removing bacterial sediment, retains supernatant; Decolouring, temperature remains on 70 ~ 90 DEG C, obtains cleaner liquid, is acidified to pH2.5 with acid, 70 ~ 90 DEG C of insulations, cooling, centrifugal or press filtration, washing, and it is dry that the precipitation after cleaning takes out final vacuum, obtains long-chain biatomic acid.
Long-chain biatomic acid in the present invention refers to the unbranched dicarboxylic acid containing more than ten carbon atoms, a kind of important fine chemistry industry intermediate raw material, particularly SL-AH (DC12), DC14 (DC14), 16-dicarboxylic acid (DC16) and DC18 (DC18).
The invention has the beneficial effects as follows, in order to break through the bottleneck producing bacterial classification genetic modification, the present invention is by resolving the genomics and transcription group feature of producing bacterial strain, analyze omega oxidation and β-oxidation pathways metabolism, genome global level establishes some critical target points that diprotic acid metabolism is relevant, by metabolic engineering means, molecular modification is carried out to these sites again, and experimental verification by fermentation, obtain the bacterial strain that performance is more excellent.TDTC002 bacterial strain of the present invention (preserving number: CGMCCNo.8927); compare DC12 bacterial strain; transformation efficiency is improved; and what is more important is under the condition of fixing dissolved oxygen; the required air flow of TDTC002 bacterial strain and rotating speed all comparatively DC12 bacterial strain are low by 25% ~ 30%; fermentation power consumption cost significantly reduces, for large-scale production brings beneficial effect.
Embodiment
In the present invention, in sequence table, sequence names is as follows: sequence 1:ACS-FRTF; Sequence 2:ACS-FRTR; Sequence 3:ACS-U; Sequence 4:ACS-D; Sequence 5:CandidaA00308; Sequence 6:CandidaA01833.
The bacterium colony observed in following examples and thalli morphology are summarized as follows:
On solid medium flat board, bacterium colony cheese shape, smooth surface, oyster white, full projection, colony diameter is about 2mm.Yeast sample is unicellular, and size is about 10x6 μm.Under most cases, with the unicellular form of yeast sample, have pseudomycelium simultaneously and formed, under stimulating at some growth phase or certain ambient conditions, pseudohypha increase more remarkable in regular meeting.
Substratum listed below employing in following examples:
1, YPD substratum, its formula is: the yeast extract paste of 1%, 2% peptone, and 2% glucose, if solid medium processed, adds 2% agar powder.Above-mentioned per-cent is quality volume percent, i.e. the grams of every 100 milliliters of substratum this component required.To add microbiotic, liquid nutrient medium is added to corresponding final concentration in use.When solid medium is cooled to 50 degrees centigrade after autoclaving, add microbiotic to corresponding final concentration, fall at once as in aseptic culture dish after mixing, rear inversion to be solidified, is put in 4 degrees Celsius of refrigerators, uses in two weeks.
2, the formula of seed culture medium: yeast extract paste 1 ~ 8g/L, corn steep liquor 1 ~ 8g/L, sucrose 5 ~ 25g/L, KH
2pO
44 ~ 12g/L, urea 0.5 ~ 4g/L, heavy wax 40 ~ 70g/L, 121 DEG C of sterilizings 30 minutes.Wherein, sucrose and urea separate independent 110 DEG C of sterilizings 20 minutes, remerge mixing after sterilizing.
3, fermentor cultivation based formulas: yeast extract paste 1 ~ 8g/L, corn steep liquor 1 ~ 8g/L, sucrose 5 ~ 30g/L, KH
2pO
44 ~ 15g/L, urea 0.5 ~ 4g/L, KNO
35 ~ 15g/L, NaCl0.5 ~ 2.5g/L, 121 DEG C of sterilizings 30 minutes.Wherein, the separately independent sterilizing of sucrose and urea, 110 DEG C of sterilizings 20 minutes, remerge mixing after sterilizing.Prepare 75% glucose solution in addition, 105 DEG C of sterilizings 20 minutes, the fermentation initial stage carries out stream and adds.
Yeast culture listed below employing in following examples and fermentation liquor treatment mode:
1, slat chain conveyor: be inverted in 30 DEG C of incubators after the flat lining out of YPD or coating, namely can be observed large and full oyster white bacterium colony for 2-3 days and is formed.
2, shaking table is cultivated: flat board is inoculated single bacterium colony in liquid nutrient medium, or comes from liquid nutrient medium switching, and 30 DEG C of shaking tables are cultivated, and rotating speed remains on 220 revs/min.
3, fermentor cultivation: accurately can control fermentation condition relatively in real time, as control of additive raw material, pH control, dissolved oxygen control and aeration-agitation intensity control etc.First stage, fermented liquid pH controls 5 ~ 6.8, and stream adds glucose solution simultaneously, is the thalli growth stage; Subordinate phase, fermented liquid pH controls 7.0 ~ 7.8, simultaneously current adding substrate (alkane, lipid acid or derivative of fatty acid, as methyl esters or ethyl ester etc.), based on fermentation and acid, also growth part thalline; Phase III, only produce acid, do not produce thalline, according to fermentation situation continued current adding substrate (alkane, lipid acid or derivative of fatty acid, as methyl esters or ethyl ester etc.).Whole fermenting process 10M NaOH solution auto-feeding control pH, makes dissolved oxygen remain on 20 ~ 40% by the adjustment of rotating speed simultaneously.
4, fermentation liquor treatment: after fermentation ends, is heated to 70 ~ 80 DEG C by fermented liquid, and maintains 60 minutes; Add 10M NaOH again and pH is adjusted to 9 ~ 9.5, with tubular-bowl centrifuge or press filtration removing bacterial sediment, retain supernatant; Add proper amount of active carbon decolouring, temperature remains on 70 ~ 90 DEG C, and soaking time is 60 minutes; After removing gac, obtain cleaner liquid, with concentrated hydrochloric acid or vitriol oil continuously acidizing to pH2.5,70 ~ 90 DEG C of insulations 2 hours, be cooled to 30 DEG C, centrifugal or press filtration, clear water washes one time, and it is dry that the precipitation after cleaning takes out final vacuum, obtains white long-chain biatomic acid.
Embodiment 1: bacterial strain metabolic engineering
1) gene order-checking
Utilize the genome of precious biotechnology company limited to extract test kit (Yeast DNAiso Kit) and prepare long-chain biatomic acid production bacterial strain candiyeast genomic dna, concrete operations are carried out according to test kit specification sheets.Genomic dna is again through steps such as library construction, new-generation sequencing technology sequencing analysis and data assemblings.By genome annotation and data analysis, obtain and produce bacterial strain and produce relevant gene information at diprotic acid, excavated the encoding sequence of this bacterium at omega oxidation and β-oxidation pathways metabolism genes involved.CandidaA00308 and Candida01833 two opening code-reading frame coding ester acyl coenzyme A synthetic enzyme, mrna length is 2157bp, and sequence similarity is up to 96%, and upstream and downstream regional sequence is also highly similar, thus can judge it is pair of alleles.
2) transcript profile order-checking
Utilize the RNA of German Kai Jie company to extract test kit (RNeasy Mini Kit) and prepare the total serum IgE that long-chain biatomic acid produces bacterial strain candiyeast, concrete operations are carried out according to test kit specification sheets.The total serum IgE obtained is again through library construction, transcript profile order-checking and expression analysis.Lipid acid or long-chain biatomic acid just can enter β-oxidation after needing to become ester acyl coenzyme A by activation.And this single step reaction carrys out catalysis by ester acyl coenzyme A synthetic enzyme completes.By transcript profile data analysis, this is respectively 2072.9 and 2001.5RPKM to equipotential gene transcription level to find CandidaA00308 and Candida01833.Here, RPKM is method of calculation of gene expression amount, represents Reads PerKb Per Million Reads.Its calculation formula is
If the expression amount that RPKM (A) is Gene A, then C is the reads number of unique comparison to Gene A, and N is the total reads number of unique comparison to reference gene, and L is the base number of Gene A coding region.RPKM method can eliminate mrna length and order-checking amount difference to the impact calculating genetic expression, and the gene expression amount calculated can be directly used in icp gene differential expression.
Because β-oxidation is the pathways metabolism that long-chain biatomic acid degraded is relevant, the object of bacterial classification transformation is the generation as far as possible avoiding diprotic acid to degrade.But β-oxidation is required for the metabolism of thalline normal physiological and energy supply on the other hand.Therefore, it is desirable to suppressed by engineered means instead of block β-oxidation completely, reach the synthesis neither affecting thalline normal growth and long-chain biatomic acid, avoid again the object that the long-chain biatomic acid synthesized is degraded.CandidaA00308 and Candida01833 is the pair of alleles of diploid DC12, and coding ester acyl coenzyme A synthetic enzyme, is responsible for activation lipid acid or diprotic acid, generates ester acyl coenzyme A, thus enter β-oxidation pathways metabolism in diprotic acid degradation pathway.Therefore, utilize metabolic engineering means, knock out this to one of them copy of allelotrope, to reach the effect suppressing diprotic acid degraded, thus reach the object of more effectively accumulation diprotic acid.
3) gene knockout experiment flow process as shown in Figure 3.Design of primers principle, homology arm and detect the design of primer and all select identical region in the comparison of CandidaA00308 and Candida01833, thus reach two allelotrope and knock out and detect there is equal probability.Hold as homology arm sequence, corresponding to the upstream and downstream sequence in gene knockout site at 5 ' of long primer ACS-FRTF and ACS-FRTR.3 ' end of these two long primers matches with the upstream and downstream knocking out module (deletioncassette) respectively.The DNA fragmentation obtained after pcr amplification, upstream and downstream homology arm is with at two respectively, and middle is resistance screening mark.
Carry out electricity after the DNA fragmentation of amplification is purified to transform in importing somatic cells, the target site generation double exchange on the upstream and downstream homology arm of DNA fragmentation and thalline karyomit(e), reaches the object of gene knockout.Because this double exchange is small probability event, need establishment method to screen.Here used resistant gene is Sat1, coding Knowles rhzomorph Transacetylase.Diprotic acid produces bacterial strain to Knowles rhzomorph (being clonNAT or NTC again) this medicaments insensitive, can not grow, and after expressing this enzyme, thalline can decompose Knowles rhzomorph, avoids lethal effect containing on the flat board of Knowles rhzomorph.Resistance screening mark is only incorporated into karyomit(e) and gets on and just can be expressed, and plays a role, and thalline can grown containing on the culture medium flat plate of resistance, and form bacterium colony.Simultaneously to the bacterium colony with resistance, carry out purifying and checking.
During checking, use a pair detection primer ACS-U and ACS-D, respectively with the upstream and downstream regions pair of target site.If do not have homologous recombination to occur, be the fragment that masterplate increases out by this pair of alleles be the same in length, a band can only be observed in agarose electrophoresis.If one of them allelotrope be substituted for by resistance gene fragment due to double cross-over event, so just change through the fragment length obtained that increases, two bands can be observed in agarose electrophoresis.Through the bacterial strain of checking, then in diprotic acid production, whether there is the advantage in performance by fermenting experiment checking metabolic engineering acquisition new strains.
4) pcr amplification
Wherein, plasmid pSFS2, to be the accession number of Gene (2004) 341:119 – 127, GeneBank database be reference: AY524979, derives from Microbe Inst., Chinese Academy of Sciences.
The Pyrobest archaeal dna polymerase of archaeal dna polymerase Shi Bao biotechnology company limited, or the Phusion archaeal dna polymerase of NEB company, activity unit is 5U/ μ l.
PCR cycling condition is:
94 degree of 2 minutes (denaturation stages)
94 degree 20 seconds, 58 degree 20 seconds, 72 degree of 1 ~ 6 minute (30 cyclic amplification stages)
72 degree 10 minutes (finally extending the stage)
5) DNA purifying
After reaction terminates, get the above-mentioned PCR sample of 5 μ l and carry out agarose electrophoresis detection, prove the amplification DNA fragmentation size of gained and the same of expectation, and assorted band, carrying out two-step purifying with concentrated, is conversion prepare dna sample below.
The first step utilizes PCR purification kit (purchased from Omega company), carries out to specifications.Be generally 50 μ l systems, do 4 pipes, cumulative volume is totally 200 μ l, the final step 50 or 100 μ l TE buffer solution elution pillars of PCR purifying.DNA after purifying, survey concentration with NanoDrop instrument, the DNA total amount calculated is about 20 μ g.
Second step is precipitated with ethanol/sodium-acetate/glycogen process by the DNA of purifying again.Specific practice is: the dehydrated alcohol adding 1 μ l glycogen (20mg/ml), 100 μ l sodium-acetate (3M, pH5.2) and 1ml precooling toward the DNA solution of the above-mentioned TE of being dissolved in damping fluid; Place-80 degrees Celsius of refrigerators and cool 30 minutes; 4 degree of whizzers, under the rotating speed of 14000 revs/min, centrifugal 10 minutes, stay precipitation; Precipitation washes twice with the ethanol of 75% precooling again; Air-dry in super clean bench; 4 degrees Celsius of refrigerator storage, it is for subsequent use that electricity is resuspended in 10 μ l ultrapure waters before turning.
6) competence preparation and electricity turn
Starting strain (Candida sp.DC12 is chosen from the flat board of fresh activation, see " microorganism journal " 20 (1): 88-93,1980, normal alkane fermentative production long-chain mixed dicarboxylic acid, can buy from Institute of Microorganism, Academia Sinica) single bacterium colony in 3ml liquid YPD medium, 30 DEG C of shaking table overnight incubation, rotating speed is 220 revs/min; 2% transfers in 20ml YPD, and 30 DEG C of shaking tables are cultivated, and 220 revs/min, reach 1.8 to OD600; Be placed in by bacterium liquid and leave standstill 15 minutes on ice, make it stop growing, 4000 revs/min, 4 DEG C centrifugal 3 minutes, stays bacterial sediment; With the aseptic washing of 4ml precooling once; 4000 revs/min, 4 DEG C centrifugal 3 minutes, stays bacterial sediment; Add 4ml TE/0.1M LiOAc, 150 revs/min, vibration 90 minutes in the shaking table of 30 DEG C; Add 0.1ml1M DTT, vibration 30 minutes in the shaking table case continuing 150 revs/min, 30 DEG C; 4000 revs/min, 4 DEG C centrifugal 3 minutes, stays bacterial sediment; Add 4ml precooling sterilized water, wash 3 times; Add 2ml1M sorbyl alcohol, wash 1 time, 4000 revs/min, 4 DEG C centrifugal 3 minutes; Abandon supernatant, add 120 μ l sorbyl alcohols and cell is hanged; The cell suspension taking out 40ul, in 1.5ml centrifuge tube, is resuspended in the pcr amplification product (about 10 μ g) of sterilized water after adding the above-mentioned purifying of 5 μ l, mixing, is placed in 5 minutes on ice; Proceed in the electric revolving cup of precooling, dry electric revolving cup, carry out electricity and turn (electricity turns condition: the electric revolving cup of 2mm slit, and voltage is 1800 volts, and the electric shock time is 5 milliseconds); Electricity adds 1ml sorbyl alcohol after turning at once, and after mixing, sucking-off is put in the centrifuge tube of 1.5ml; 4000 revs/min centrifugal 3 minutes, abandons supernatant, adds 1ml YPD substratum, cultivates 2 hours in the shaking table of 37 DEG C; 4000 revs/min centrifugal 3 minutes, abandons supernatant, adds the resuspended thalline of 100 μ l YPD, spread plate (YPD+clonNAT), is put in 30 DEG C of incubators and is cultured to the appearance of single bacterium colony.
7) resistant clones is screened
Be inoculated into respectively in the centrifuge tube of 1ml YPD substratum by single bacterium colony that above-mentioned resistant panel grows, adding clonNAT to final concentration is 100 μ g/ml, 220 revs/min, and 30 DEG C of shaking tables are cultivated.Occur growth, illustrate with resistance, proves that resistant gene to be incorporated in phage gene group and to have played a role, this part bacterium colony is used for next step and verifies.Do not occur the bacterium colony grown, explanation is false positive, is equal to starting strain, stops process.
8) identify
Occur the resistant clones grown above, inoculation YPD liquid nutrient medium overnight incubation, draws 500 μ l bacterium liquid, and utilize the genome of precious biotechnology company limited to extract test kit and prepare genomic dna, concrete operations are carried out according to test kit specification sheets.With the genomic dna obtained for masterplate, ACS-U and ACS-D is that primer carries out pcr amplification, and concrete reaction system and reaction conditions are with reference to the 4th of the present embodiment 1) article.If the allelotrope on target site is not knocked, the DNA fragmentation size increasing out from two allelosomals is the same, and agarose electrophoresis shows as a band.If one of them allelotrope is knocked on target site, the DNA fragmentation increasing out from two allelosomals is in different size, and agarose electrophoresis shows as two bands (see Fig. 3).Be accredited as the bacterium liquid that the positive and target site of resistance is knocked, more further through the qualification of bacterium colony purifying and same procedure, obtain long-chain biatomic acid of the present invention and produce bacterial strain TDTC002.
Embodiment 2: the fermentative production of long-chain biatomic acid
Bacterial classification is by after conventional slant culture, and access 50ml first order seed cultivates 16 hours, and then being cultivated by first order seed transfers cultivates 16 hours into 500ml secondary seed.
The formula of seed culture medium: yeast extract paste 1 ~ 8g/L, corn steep liquor 1 ~ 8g/L, sucrose 5 ~ 25g/L, KH
2pO
44 ~ 12g/L, urea 0.5 ~ 4g/L, heavy wax 40 ~ 70g/L, 121 DEG C of sterilizings 30 minutes.Wherein, sucrose and urea separate independent 110 DEG C of sterilizings 20 minutes, remerge mixing after sterilizing.
After secondary seed has fermented, transfer into 5L fermentor tank.Fermentor cultivation based formulas: yeast extract paste 1 ~ 8g/L, corn steep liquor 1 ~ 8g/L, sucrose 5 ~ 30g/L, KH
2pO
44 ~ 15g/L, urea 0.5 ~ 4g/L, KNO
35 ~ 15g/L, NaCl0.5 ~ 2.5g/L, 121 DEG C of sterilizings 30 minutes.Wherein, the separately independent sterilizing of sucrose and urea, 110 DEG C of sterilizings 20 minutes, remerge mixing after sterilizing.Prepare 75% glucose solution in addition, 105 DEG C of sterilizings 20 minutes, the fermentation initial stage carries out stream and adds.Basic medium is 4L.At 30 DEG C with the ventilation volume of 1:0.5, control pH5.5 ~ 6.5, started to add 12 carbon straight-chain paraffins with the speed stream of 50ml/h after the 16th hour, fermentation time is 144-156 hour.Whole fermenting process 10M NaOH solution auto-feeding control pH, makes dissolved oxygen remain on 30% by the adjustment of rotating speed simultaneously.
As shown in Figure 4 and Figure 5, HPLC analyzes and shows starting strain DC12 and transform the ferment long-chain biatomic acid product that obtains of bacterial strain TDTC002 consistent, and purity all (is respectively 98.5% and 98.9%) more than 98.5%.As can be seen from following table, improved bacterial strain, transformation efficiency is also improved.
Embodiment 3
According to the method for embodiment 2, just substrate changes Laurate methyl into from 12 carbon straight-chain paraffins.
Embodiment 4
According to the method for embodiment 2, just substrate changes Laurate ethyl into from 12 carbon straight-chain paraffins.