CN102250820B - Genetic engineering bacteria of gluconobacter oxydans and construction methods thereof - Google Patents
Genetic engineering bacteria of gluconobacter oxydans and construction methods thereof Download PDFInfo
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Abstract
The invention discloses a genetic engineering bacterium of gluconobacter oxydans, which is the gluconobacter oxydans lacking of an s-ArDH gene. The invention also discloses a genetic engineering bacterium of gluconobacter oxydans, which lacks of an s-ArDH gene and uses the gluconobacter oxydans enhanced by XDH (Xylitol Dehydrogenase) on the position of the s-ArDH gene. The invention also discloses a construction method of two genetic engineering bacteria. The genetic engineering bacteria of the gluconobacter oxydans provided by the invention can block a reverse reaction of xylulose to generate D-arabitol in the process of transforming D-arabitol to prepare xylitol by using a biological method so that the problem of accompanying by-products in the process of manufacturing the xylitol is further radically solved; moreover, an XDH enhanced bacterial strain improves the dehydrogenase activity of the xylitol and increases the conversion rate of the xylitol.
Description
Present patent application is to be 201010190935.2 divide an application for original applying number.
Technical field
The invention belongs to gene engineering technology field, be specifically related to strain Gluconobater oxydans genetic engineering strain and a construction process thereof.
Background technology
Xylitol is natural five-carbon sugar alcohol, is one of important functional food additives.The sugariness of Xylitol is 1.05 times of sucrose, and heat and sucrose are suitable, and its metabolism does not need Regular Insulin, and alternative sucrose is as the sweeting agent of patients with diabetes mellitus.Xylitol is by fermentation using bacteria, is used in the chewing gum as sweeting agent, has the function of keeping oral cavity acid base equilibrium, preventing dental caries.There are some researches show that Xylitol can stop the combination of bacterium and human body cell, preventing respiratory tract infection; Xylitol promotes enteron aisle to calcareous absorption in addition, reduces bone-loss, keeps the effects such as normal bone density and reduction liver transaminase.Along with the increase of people to healthy attention degree, the demand of Xylitol will be more and more higher.
Present Xylitol production method is mainly chemical method and namely adopts corn cob, bagasse etc. to be rich in the poly-pentose raw material of (containing 36～40% pentosan), become to contain the liquid glucose of wood sugar through acid hydrolysis, then the scavenging process separation and purification from hydrolyzed solution through complexity such as neutralization, decolouring, ion-exchange, crystallizations goes out wood sugar, follows chemical hydrogenation and makes wood sugar generate Xylitol.Chemical method prepares Xylitol and has two large common issue with: (1) resources and environment pollution problem is serious.Studies show that and produce 1 ton of Xylitol that can produce 6 tons of acid corn cob residues, processing these residues then needs 2 tons of coals.Because environmental issue is difficult to solve, 2005, the maximum foodstuff additive company-Danisco in the whole world was closed the production line of 10,000 ton/years of Xylitols.(2) cost of material is high, and has potential there is lack of raw materials risk.Because China's corn cob is in a large number for the production of Xylitol, furfural and edible mushrooms in recent years, the raw material problem shows especially, causes like this production cost of Xylitol to increase.
In order to solve the resources and environment problem of Xylitol in producing, many people are devoted to develop that a kind of to adopt wide material sources, cheap starch or glucose be that raw material is produced Xylitol.Reported a kind of method for preparing Xylitol from glucose such as Onishi and Suzuki, at first oozing yeast D.hansenii by height is D-R alcohol (D-arabitol with conversion of glucose, D-ara), then be oxidized to the D-xylulose under the effect of Acetobacter suboxydans, last D-xylulose is reduced to Xylitol under yeast C.guilliermondii effect.To a strain one step of arabitol high-performance bio is converted into the oxidizing glucose acidfast bacilli (Gluconobacter oxydans) of Xylitol such as seed selections such as the Japanese Suzuki of Ajincomoto Co., Inc, Xylitol biosynthesizing route is reduced to two bacterium two-step approachs, the first step utilizes saccharomycetes to make fermentation glucose efficiently to prepare D-R alcohol, second step is by this bacterium Efficient Conversion D-R alcohol preparation Xylitol, and operational path is as follows:
Wherein, the route of synthesis of second step oxidizing glucose acidfast bacilli catalysis D-R alcohol product Xylitol is as follows:
More than in the mentioned production bacterium of these methods the transformation efficiency of principal product lower, do not satisfy the requirement of suitability for industrialized production.
We have also developed the technique that a kind of two-step approach bio-transformation glucose prepares Xylitol, be that the first step utilizes Kodamaea ohmeri NH-9 glucose fermentation efficiently to prepare D-R alcohol, second step transforms D-R alcohol by Gluconobacteroxydans NH-10 (CGMCC No.2709) and produces Xylitol.In our previous work, find to exist among the CGMCC No.2709 two kinds of D-R alcoholdehydrogenase (D-Arabitol dehydrogenase, ArDH), be that film is in conjunction with PQQ-dependent form D-R alcoholdehydrogenase (Membrane-bound PQQ-dependent D-arabitoldehydrogenase, m-ArDH) and solubility NADP-dependent form D-R alcoholdehydrogenase (SolubleNADP-dependent D-arabitol dehydrogenase, s-ArDH).Because the existence of s-ArDH, in reduction process, s-ArDH can be reduced to D-R alcohol with D-xylulose (D-xylulose), and this not only affects the productive rate of Xylitol, and is unfavorable for the separation of derived product.In addition, the xylitol dehydrogenase in this bacterium (Xylitol dehydrogenase, XDH) vigor is relatively low, becomes the bottleneck that the biological process transforming glucose produces Xylitol technique.
Summary of the invention
First technical problem to be solved by this invention provides the Gluconobater oxydans genetic engineering strain that a plant height produces Xylitol.
The technical problem that the present invention also will solve provides the construction process of above-mentioned Gluconobater oxydans genetic engineering strain.
For solving the problems of the technologies described above, the technical solution used in the present invention is as follows:
A kind of Gluconobater oxydans genetic engineering strain, this bacterium are the oxidizing glucose acidfast bacillis (Gluconobacter oxydans) of disappearance NADP-pectinose alcoholdehydrogenase (s-ArDH) gene, hereinafter to be referred as s-ArDH disappearance bacterium.
The construction process of above-mentioned s-ArDH disappearance bacterium comprises the steps:
(1) design of primers:
The Gluconobacter oxydans 621H gene s-ardh sequence of announcing according to GenBank is two pairs of special primers of basic design, and primer is as follows:
s-ardh L-fwd：5’TAT
GAATTCCCTCTTGAAAACCTATCATAGC-3’EcoR I，
s-ardh L-rev：5’-CTGTTTATGTAAGC
CTCGAGAAACTTGAAGTCC-3’Xho I，
s-ardh R-fwd：5’-AATAAACAAATAG
CTCGAGAAAATGGCCGGGAAG-3’Xho I，
s-ardh R-rev：5’-AT
GAATTCATGGCGACTGTCGAACTCAAG-3’EcoR I。
S-ardh L-fwd and s-ardh R-rev primer two ends add same restriction enzyme site EcoR I and protection base.S-ardh L-rev and s-ardh R-fwd primer two ends add same restriction enzyme site Xho I, and underscore partly is restriction enzyme site.
(2) s-ardh L, s-ardh R gene cloning:
By round pcr, take Gluconobacter oxydans strain gene group DNA as template, each 800bp left and right sides sequence of s-ardhL and s-ardh R increases respectively.
The method of s-ardh L gene clone is: adopt round pcr, take Gluconobacter oxydans strain gene group DNA as template, carry out pcr amplification with primer s-ardh L-fwd, s-ardh L-rev; The PCR reaction conditions is: 10 * PCRbuffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer s-ardh L-fwd and s-ardh L-rev, exTaq DNApolymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 60.5 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min, with the negative contrast of distilled water.
The method of s-ardh R gene clone is: adopt round pcr, take Gluconobacter oxydans strain gene group DNA as template, carry out pcr amplification with primer s-ardh R-fwd, s-ardh R-rev; The PCR reaction conditions is: 10 * PCRbuffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer s-ardh R-fwd and s-ardh R-rev, exTaq DNApolymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 61 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min, with the negative contrast of distilled water.
(3) acquisition of resistance fragment Km:
The card of announcing according to GenBank is received mycin resistant gene Km sequence, designs a pair of Auele Specific Primer km-fwd and km-rev, the complete CDs take pET28a (+) plasmid as template amplification Km, and primer is as follows:
km-fwd：5’-GGACTTCAAGTTT
CTCGAGGCTTACATAAACAG-3’Xho I，
km-rev：5’-CTTCCCGGCCATTTT
CTCGAGCTATTTGTTTATT-3’Xho I，
Km-fwd and km-rev primer two ends add same restriction enzyme site Xho I and protection base, and underscore partly is restriction enzyme site, amplifies 900bp left and right sides sequence.
The preparation method of Km is: adopt round pcr, take pET28a (+) plasmid as template, carry out pcr amplification with primer km-fwd, km-rev; The PCR reaction conditions is: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer km-fwd and km-rev, exTaq DNA polymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 61.5 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min, with the negative contrast of distilled water.
S-ardh L, s-ardh R and Km difference glue recovery purifying is for subsequent use.
(4) structure of pMD18-KR:
The s-ardh R of purifying is connected by overlapping PCR method with the Km fragment, the acquisition size is the fragment KR about 1700bp, be connected with the pMD18-T carrier, be converted among the competence E.coli JM109, obtain to contain the recombinant plasmid pMD18-KR of target gene by containing the screening of Amp and Km resistant panel.
The gene clone method of fragment KR is: adopt round pcr, take s-ardh R and Km fragment as template, carry out overlapping pcr amplification with primer km-fwd, s-ardh R-rev; In two steps amplification of PCR reaction;
The first step system is as follows: 10 * PCR buffer, 2.5 μ L, Mg
2+2 μ L, dNTP 2 μ L, each 2 μ L of s-ardh R fragment and Km fragment, exTaq DNA polymerase 0.5 μ L adds ddH
2O is 25 μ L to reacting cumulative volume; Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 55s, 65 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 5 times; 72 ℃ prolong 2min;
Second step adds in the first step PCR product: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 4 μ L, each 2 μ L of primer km-fwd and primer s-ardh R-rev, exTaq DNA polymerase 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 50s, 60 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min.
(5) structure of pMD18-LKR:
S-ardh L is connected by overlapping PCR method with the KR fragment, the acquisition size is the fragment LKR about 2500bp, be connected with the pMD18-T carrier, be converted among the competence E.coli JM109, obtain to contain the recombinant plasmid pMD18-LKR of target gene by the LB plate screening that contains Amp and Km.
The gene clone method of fragment LKR is: adopt round pcr, take s-ardh L and KR fragment as template, carry out overlapping pcr amplification with primer s-ardh L-fwd, s-ardh R-rev, the PCR reaction is increased in two steps;
The first step system is as follows: 10 * PCR buffer, 2.5 μ L, Mg
2+2 μ L, dNTP 2 μ L, each 2 μ L of s-ardh L fragment and KR fragment, exTaq DNA polymerase 0.5 μ L adds ddH
2O is 25 μ L to reacting cumulative volume; Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 55s, 65 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 5 times; 72 ℃ prolong 2min;
Second step adds in the first step PCR product: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 4 μ L, each 2 μ L of primer s-ardh L-fwd and primer s-ardh R-rev, exTaq DNA polymerase 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 50s, 59 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min.
(6) structure of s-ardh gene knockout carrier pSUP202-s-ardh::Km:
Recombinant plasmid pMD18-LKR is cut with EcoR I enzyme; Carrier pSUP202 cuts the rear CIAP of using dephosphorylation with EcoR I enzyme; The carrier pSUP202 that LKR fragment after enzyme cut is connected with dephosphorylation connects with the T4 ligase enzyme, is converted among the competence E.coli JM109, obtains to contain the recombinant plasmid pSUP202-s-ardh::Km of target gene by the LB plate screening that contains Amp and Km.
(7) acquisition of s-ardh gene knockout mutant G.oxydans s-ardh::Km mutant NSA18:
To contain the E.coli JM109 that knocks out mutational vector pSUP202-s-ardh::Km and be used for three parent's joints as the donor bacterium, recipient bacterium is G.oxydans; Knock out mutational vector and enter G.oxydans under the help that helps bacterium pRK2013, the target gene fragment that will contain the Km gene is incorporated on the karyomit(e) of G.oxydans, screens three close zygotes by Cefotaxime, Km.
Three parents engage knockout techniques and are: respectively with donor bacterium E.coli JM109/pSUP202-s-ardh::Km, help bacterium JM109/pRK2013 to be seeded in to be added with 25 μ g/mL cards to receive overnight incubation in the LB substratum of mycin, recipient bacterium G.oxydans is seeded in G-Ara and cultivates 15～20h, A
660Value is to engage experiment at 0.6～1.0 o'clock; Press the receptor parent bacterium: help bacterium: the bacteria liquid of donor bacterium=3: 1: 3 is long-pending than collecting thalline, transfers on the solid G-Ara substratum of added with antibiotic not, is inverted 30 ℃ of overnight incubation; The resistance that has with G.oxydans add on the recombinant plasmid with resistance, screen corresponding transformant; Three close zygomycetes body and function aseptic double-distilled waters of overnight incubation are washed from solid G-Ara substratum, be coated onto and add 5 μ g/mL cefotaxime acids and 25 μ g/mL cards and receive on the G-Ara flat board of mycin, cultivated 2～4 days, grow zygote and carry out PCR and verify.
A kind of Gluconobater oxydans genetic engineering strain, it is characterized in that this bacterium is disappearance s-ArDH gene, and the oxidizing glucose acidfast bacilli (Gluconobacter oxydans) in that the position of s-ArDH gene strengthens with the XDH gene strengthens bacterium hereinafter to be referred as the XDH gene.
Above-mentioned XDH gene strengthens the construction process of bacterium, comprises the steps:
Step (1)～(7) are with the construction process of s-ArDH disappearance bacterium;
(8) design of primers:
The Gluconobacter oxydans 621H gene xdh sequence of announcing according to GenBank is two pairs of special primers of basic design, and primer is as follows:
xdh-fwd：5’-AGG
CTCGAGTCGAAGAAGTTTAAG-3’Xho I，
xdh-rev：5’-ATT
CTCGAGTCAACCGCCAGCAAT-3’Xho I。
Xdh-fwd and xdh-rev primer two ends add same restriction enzyme site Xho I, and underscore partly is restriction enzyme site.
(9) xdh gene cloning:
By round pcr, take Gluconobacter oxydans strain gene group DNA as template, amplification 800bp left and right sides xdh sequence.
The method of xdh gene clone is: adopt round pcr, take Gluconobacter oxydans strain gene group DNA as template, carry out pcr amplification with primer xdh-fwd, xdh-rev, the PCR reaction conditions is: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer xdh-fwd and xdh-rev, exTaq DNA polymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 53.6 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min.
(10) the xdh gene strengthens the structure of carrier pSUP202-s-ardh::xdh:
The plasmid pMD18-xdh that will contain target gene cuts with Xho I enzyme, and glue reclaims the purpose fragment; Carrier pSUP202-s-ardh::Km cuts the rear CIAP of using dephosphorylation with Xho I enzyme; The carrier that purpose fragment after enzyme cut is connected with dephosphorylation connects with the T4 ligase enzyme, is converted among the competence E.coli JM109, obtains to contain the recombinant plasmid pSUP202-s-ardh::xdh of target gene by containing the screening of Amp and Km resistant panel;
(11) the xdh gene strengthens the acquisition of mutant G.oxydans s-ardh::xdh NSAX31: will contain the E.coli JM109 that knocks out mutational vector pSUP202-s-ardh::xdh and be used for three parent's joints as the donor bacterium, recipient bacterium is G.oxydanss-ardh::Km mutant NSA18; Knock out mutational vector and enter G.oxydansNSA18 under the help that helps bacterium pRK2013, the target gene fragment that will contain the xdh gene is incorporated on the karyomit(e) of G.oxydans NSA18; Screen three close zygotes by Cefotaxime, Km.
The methods that three parents engage to strengthen are: with donor bacterium E.coli JM109/pSUP202-s-ardh::xdh, help bacterium JM109/pRK2013 to be seeded in respectively to be added with 100 μ g/mL penbritins and 25 μ g/mL cards to receive overnight incubation in the LB substratum of mycin, recipient bacterium G.oxydans s-ardh::Km mutant NSA18 is seeded in G-Ara and cultivates 15～20h, A
660Value is to engage experiment at 0.6～1.0 o'clock; Press the receptor parent bacterium: help bacterium: the bacteria liquid of donor bacterium=3: 1: 3 is long-pending than collecting thalline, transfers on the solid G-Ara substratum of added with antibiotic not, is inverted 30 ℃ of overnight incubation; The resistance that has with G.oxydans add on the recombinant plasmid with resistance, screen corresponding transformant; Three close zygomycetes body and function aseptic double-distilled waters of overnight incubation are washed from solid G-Ara substratum, be coated onto on the G-Ara flat board that adds 5 μ g/mL cefotaxime acids, cultivated 2～4 days, grow zygote and carry out the PCR checking.
Beneficial effect: the present invention compared with prior art has following advantage:
1, the present invention successfully obtains the s-ardh gene knock-out bacterial strain.S-ardh gene knockout carrier pSUP202-s-ardh::Km enters in the CGMCC No.2709 thalline under the help that helps bacterium pRK2013, replace the s-ardh gene by homologous recombination, through the gene level screening and identification, successfully obtain lacking the G.oxydans bacterial strain of s-ardh gene, i.e. G.oxydanss-ardh::Km NSA18 bacterial strain.This bacterial strain can be blocked the approach that the D-xylulose generates D-R alcohol, improves the Xylitol productive rate, and then fundamentally solves the problem of D-R alcohol association in the Xylitol production process.
2, the present invention successfully obtains xdh gene enhancing bacterial strain.The xdh gene strengthens carrier pSUP202-s-ardh::xdh and enters in the CGMCC No.2709 NSA18 thalline under the help that helps bacterium pRK2013, replace the km gene by homologous recombination, through the gene level screening and identification, successfully obtain the CGMCC No.2709 bacterial strain that xdh strengthens, i.e. CGMCC No.2709s-ardh::xdhNSAX31 bacterial strain.This bacterial strain can be used for blocking-up D-xylulose and generate the approach of D-R alcohol and strengthen the xylitol dehydrogenase vigor, in solving the Xylitol production process in the problem of D-R alcohol association, improved greatly the Xylitol productive rate, and then from reach the purpose of xylitol products quality and deep development at all.
Description of drawings
Fig. 1 is G.oxydans s-ardh::Km NSA18 strain construction collection of illustrative plates.Gene knockout plasmid pSUP202-s-ardh::Km and G.oxydans karyomit(e) obtain the G.oxydans s-ardh::Km NSA18 karyomit(e) of disappearance s-ardh gene by homologous recombination.
Fig. 2 is G.oxydans s-ardh::xdh NSAX31 strain construction collection of illustrative plates.Gene knockout plasmid pSUP202-s-ardh::xdh and G.oxydans s-ardh::Km NSA18 karyomit(e) obtain the G.oxydans s-ardh::xdh NSAX31 karyomit(e) that the xdh gene strengthens by homologous recombination.
Fig. 3 is that CGMCC No.2709 genomic dna is s-ardh L and the s-ardhR gene of the about 800bp of template pcr amplification.Swimming lane M:DL15000Marker; Swimming lane 1,2 is respectively s-ardh L and s-ardh R gene fragment.
Fig. 4 is take the Km gene of pET28 (a+) as the about 900bp of template pcr amplification.Swimming lane M:DL15000Marker; Swimming lane 1 is the Km gene fragment.
Fig. 5 is the KR fragment of the about 1700bp of overlapping pcr amplification.Swimming lane M:DL2000Marker; Swimming lane 1:KR gene fragment.
The LKR fragment of the about 2500bp of the overlapping pcr amplification of Fig. 6.Swimming lane M:DL2000Marker; Swimming lane 1,2:LKR gene fragment.
Fig. 7 is that the enzyme of pSUP202-s-ardh::Km is cut the checking collection of illustrative plates.Swimming lane M:DL15000Marker; Swimming lane 1,2 is respectively pSUP202-s-ardh::Km EcoR I and singly cuts the I﹠amp with EcoR; Xho I is two to be cut.
Fig. 8 is that PCR identifies that s-ardh knocks out mutant.Swimming lane M:DL2000Marker; Swimming lane 1 is the product of primer s-ardhL-fwd and km-rev, and swimming lane 2 is the product of primer km-fwd and km-rev.
Fig. 9 is take the xdh gene of CGMCCNo.2709 genomic dna as the about 800bp of template pcr amplification.Swimming lane M:DL2000Marker; Swimming lane 1 is the xdh gene fragment.
Figure 10 is that the enzyme of pSUP202-s-ardh::xdh is cut the checking collection of illustrative plates.Swimming lane M is DL15000Marker; Swimming lane 1,2 is singly cut for pSUP202-s-ardh::xdh plasmid EcoR I.
Figure 11 is that PCR identifies that xdh strengthens mutant.Swimming lane M is DL15000Marker; Swimming lane 1 is the product of primer s-ardhL-fwd and s-ardh R-rev; Swimming lane 2 is the product of primer s-ardh L-fwd and xdh-rev; Swimming lane 3 is the product of primer xdh-fwd and s-ardh R-rev.
Embodiment
According to following embodiment, the present invention may be better understood.Yet, those skilled in the art will readily understand that embodiment is described only to be used for explanation the present invention, and should also can not limit the present invention described in detail in claims.
The employed oxidizing glucose acidfast bacilli of following examples is oxidizing glucose acidfast bacilli NH-10 (Gluconobacter oxydans NH-10), its culture presevation numbering CGMCC No.2709.
The structure of the knockout carrier of embodiment 1:NADP-pectinose alcohol dehydrogenase gene.
(1) obtains s-ardh upstream region of gene s-ardh L and downstream s-ardh R and Km gene.
The Gluconobacter oxydans 621H gene s-ardh sequence of announcing take GenBank is as two pairs of primers of basic design:
s-ardh L-fwd：5’-TAT
GAATTCCCTCTTGAAAACCTATCATAGC-3’EcoR I，
s-ardh L-rev：5’-CTGTTTATGTAAGC
CTCGAGAAACTTGAAGTCC-3’Xho I，
s-ardh R-fwd：5’-AATAAACAAATAG
CTCGAGAAAATGGCCGGGAAG-3’Xho I，
s-ardh R-rev：5’-AT
GAATTCATGGCGACTGTCGAACTCAAG-3’EcoR I。
S-ardh L-fwd and s-ardh R-rev primer two ends add same restriction enzyme site EcoR I and protection base.S-ardh L-rev and s-ardh R-fwd primer two ends add same restriction enzyme site Xho I, and underscore partly is restriction enzyme site.
Pass through round pcr, take CGMCC No.2709 genomic dna as template,, primer obtains s-ardh gene 5 ' end upstream and 3 ' end downstream s-ardh L and each 800bp left and right sides sequence of s-ardh R as increasing respectively take s-ardh L-fwd and s-ardhL-rev, s-ardh R-fwd and s-ardh R-rev.
The PCR reaction conditions of s-ardh L gene is: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer s-ardh L-fwd and s-ardh L-rev, exTaq DNA polymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR reaction is carried out at the PCR instrument, and the PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 60.5 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min, with the negative contrast of distilled water.(Fig. 3).
The PCR reaction conditions of s-ardh R gene is: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer s-ardh R-fwd and s-ardh R-rev, exTaq DNA polymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR reaction is carried out at the PCR instrument, and the PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 61 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min, with the negative contrast of distilled water.(Fig. 3).
The card of announcing according to GenBank is received mycin resistant gene Km sequence, designs a pair of Auele Specific Primer km-fwd and km-rev, the complete CDs take pET28a (+) plasmid as template amplification Km:
km-fwd：5’-GGACTTCAAGTTT
CTCGAGGCTTACATAAACAG-3’Xho I，
km-rev：5’-CTTCCCGGCCATTTT
CTCGAGCTATTTGTTTATT-3’Xho I，
Km-fwd and km-rev primer two ends add same restriction enzyme site Xho I and protection base, and underscore partly is restriction enzyme site, amplifies 900bp left and right sides sequence.
Adopt round pcr, take pET28a (+) plasmid as template, carry out pcr amplification with primer km-fwd, km-rev, the PCR reaction conditions is: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer km-fwd and km-rev, exTaq DNA polymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR reaction is carried out at the PCR instrument, and the PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 61.5 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min, with the negative contrast of distilled water (Fig. 4).
The purpose band that s-ardh L-fwd and s-ardh L-rev, s-ardh R-fwd and s-ardh R-rev, km-fwd and three pairs of primer amplifications of km-rev are obtained corresponding size respectively glue to reclaim purifying for subsequent use.
(2) structure of pMD18-KR.
The s-ardh R of purifying is connected by overlapping PCR method with the Km fragment, the acquisition size is the fragment KR about 1700bp, namely take s-ardh R and Km fragment as template, carry out overlapping pcr amplification with primer km-fwd, s-ardh R-rev, in two steps amplification of PCR reaction, the first step system is as follows: 10 * PCR buffer, 2.5 μ L, Mg
2+2 μ L, dNTP2 μ L, each 2 μ L of s-ardh R fragment and Km fragment, exTaq DNA polymerase 0.5 μ L adds ddH
2O is 25 μ L to reacting cumulative volume.Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 55s, 65 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 5 times; 72 ℃ prolong 2min.Second step adds on the first step reaction basis again: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 4 μ L, each 2 μ L of primer km-fwd and primer s-ardh R-rev, exTaq DNA polymerase 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume.Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 50s, 60 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min.Glue reclaims purifying 1700bp KR fragment (Fig. 5), get KR fragment 4.5 μ L and together add an eppendorf pipe with pMD18-T 0.5 μ L and solution I 5 μ L, behind the mixing, 16 ℃ connect 3h, Transformed E .coli JM109 competent cell, coat and contain incubated overnight on Amp and the Km resistant panel, the single bacterium colony of picking carries out incubated overnight, extract plasmid, cut 37 ℃ of water-bath 2h with EcoR I and Xho I enzyme, agarose gel electrophoresis is identified, can see each appearance of 800bp and 900bp band, double digestion is identified positive bacterium order-checking, obtain recombinant plasmid pMD18-KR.
(3) structure of pMD18-LKR
S-ardh L is connected by overlapping PCR method with the KR fragment, the acquisition size is the fragment LKR about 2500bp, namely take s-ardh L and KR fragment as template, carry out overlapping pcr amplification with primer s-ardh L-fwd, s-ardh R-rev, in two steps amplification of PCR reaction, the first step system is as follows: 10 * PCR buffer, 2.5 μ L, Mg
2+2 μ L, dNTP 2 μ L, each 2 μ L of s-ardh L fragment and KR fragment, exTaq DNA polymerase 0.5 μ L adds ddH
2O is 25 μ L to reacting cumulative volume.Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 55s, 65 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 5 times; 72 ℃ prolong 2min.Second step adds on the first step reaction basis again: 10 * PCRbuffer, 5 μ L, Mg
2+2 μ L, dNTP 4 μ L, each 2 μ L of primer s-ardh L-fwd and primer s-ardh R-rev, exTaqDNA polymerase 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume.Amplification program is as follows: 95 ℃ of denaturation 4min; 94 ℃ of sex change 50s, 59 ℃ of annealing 40s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min.Glue reclaims purifying 2500bp LKR fragment (Fig. 6), get LKR fragment 4.5 μ L and together add an eppendorf pipe with pMD18-T 0.5 μ L and solution I5 μ L, behind the mixing, 16 ℃ connect 3h, Transformed E .coli JM109 competent cell, coat and contain incubated overnight on Amp and the Km resistant panel, the single bacterium colony of picking carries out incubated overnight, extract plasmid, with EcoR I single endonuclease digestion, 37 ℃ of water-bath 2h, agarose gel electrophoresis is identified, can see that the 2500bp band occurs, enzyme be cut identified positive bacterium order-checking, obtain recombinant plasmid pMD18-LKR.
(4) structure of s-ardh gene knockout carrier pSUP202-s-ardh::Km
Recombinant plasmid pMD18-LKR is cut with EcoR I enzyme; Carrier pSUP202 cuts rear with alkaline phosphatase CIAP dephosphorylation with EcoR I enzyme; Get respectively LKR fragment and carrier pSUP202 enzyme and cut each 4 μ L of product, be connected each 1 μ L of buffer and T4 dna ligase with T4 DNA and add simultaneously an eppendorf pipe, behind the mixing, 16 ℃ of connections are spent the night, Transformed E .coli JM109 competent cell, be added with an amount of Amp and the Km flat board is selected recon, the thalline electrophoresis is selected band hysteresis bacterial strain, again by EcoR I single endonuclease digestion and EcoR I ﹠amp; Xho I double digestion checking (Fig. 7).Enzyme is cut the result and shown: EcoR I single endonuclease digestion recombinant plasmid can downcut about 2.5kb size fragment, EcoR I; Xho I double digestion plasmid can downcut the fragment of about 900bp and 800bp size, conforms to expected results, illustrates the LKR fragment to be connected on the pSUP202 carrier called after pSUP202-s-ardh::Km.
The acquisition of embodiment 2:s-ardh gene knockout mutant
To contain the E.coli JM109 that knocks out mutational vector pSUP202-s-ardh::Km and be used for three parent's joints as the donor bacterium, recipient bacterium is CGMCC No.2709.Knock out mutational vector and enter CGMCCNo.2709 under the help that helps bacterium pRK2013, the target gene fragment that will contain the Km gene is incorporated on the karyomit(e) of G.oxydans NH-10.Screen three close zygotes by Cefotaxime, Km.
Respectively with donor bacterium E.coli JM109/pSUP202-s-ardh::Km, help bacterium JM109/pRK2013 to be seeded in to be added with card to receive overnight incubation in the LB substratum of mycin, recipient bacterium G.oxydans is seeded in G-Ara cultivation 15～20h, A
660Value is to engage experiment at 0.6～1.0 o'clock; Press the receptor parent bacterium: help bacterium: the bacteria liquid of donor bacterium=3: 1: 3 is long-pending than collecting thalline, be receptor parent bacterium liquid 1.5mL, centrifugal collection thalline, outwell supernatant, after washing twice with physiological saline, outwell liquid, add 0.5mL and help bacterium liquid, add 1.5mL donor bacterium behind the centrifugal collection thalline, wash once with G-Ara behind the centrifugal collection thalline, outwell liquid, in remaining a small amount of substratum with cell micropipet mixing, transfer on the solid G-Ara substratum of added with antibiotic not, be inverted 30 ℃ of overnight incubation; The resistance that has with G.oxydans add on the recombinant plasmid with resistance, screen corresponding transformant; Three close zygomycetes body and function aseptic double-distilled waters of overnight incubation are washed from solid G-Ara substratum, be coated onto on the G-Ara flat board that adds cefotaxime acid and Ka Na mycin, cultivated 2～4 days.
Picking can be cultivated containing the bacterium colony that Cefotaxime and Km resistant panel grow, and the centrifugal collection thalline of single bacterium colony culture is resuspended, add Proteinase K, behind 42 ℃ of 2h, boil 7min, 4 ℃ of centrifugal collection supernatants are template to be detected, prepare simultaneously the template supernatant of CGMCC No.2709; With s-ardh L-fwd and km-rev and km-fwd and km-rev primer, carry out respectively pcr amplification, s-ardh L-fwd and km-rev amplification PCR product carry out sequencing analysis, filtering out restructuring has the CGMCC No.2709 of Km gene, evaluation through gene level, success obtains the CGMCC No.2709 bacterial strain of s-ardh disappearance, i.e. CGMCC No.2709s-ardh::Km mutant NSA18 bacterial strain (Fig. 8).
Embodiment 3: xylitol dehydrogenase strengthens Vector construction.
(1) obtains the xdh gene
The Gluconobacter oxydans 621H gene xdh sequence of announcing take GenBank is as a pair of special primer of basic design, and primer is as follows:
xdh-fwd：5’-AGG
CTCGAGTCGAAGAAGTTTAAG-3’Xho I，
xdh-rev：5’-ATT
CTCGAGTCAACCGCCAGCAAT-3’Xho I。
By round pcr, take CGMCC No.2709 strain gene group DNA as template, with xdh-fwd and xdh-rev amplification 800bp left and right sides xdh sequence (Fig. 9).Xdh-fwd and xdh-rev primer two ends add same restriction enzyme site Xho I, and underscore partly is restriction enzyme site.
Xdh gene PCR reaction conditions is: 10 * PCR buffer, 5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer xdh-fwd and xdh-rev, exTaq DNA polymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR reaction is carried out at the PCR instrument, and the PCR program is: 94 ℃ of denaturation 2min, 94 ℃ of sex change 30s, 53.6 ℃ of annealing 30s, 72 ℃ of extension 1min, circulate 30 times, and 72 ℃ prolong 10min.
Xdh glue is reclaimed purifying, get xdh fragment 4.5 μ L and together add an eppendorf pipe with pMD18-T 0.5 μ L and solution I 5 μ L, behind the mixing, 16 ℃ connect 3h, Transformed E .coli JM109 competent cell, coat and contain incubated overnight on the Amp resistant panel, the single bacterium colony of picking carries out incubated overnight, extract plasmid, cut 37 ℃ of water-bath 2h with Xho I enzyme, agarose gel electrophoresis is identified, can see that the 800bp band occurs, enzyme be cut identified positive bacterium order-checking, obtain recombinant plasmid pMD18-xdh.
(2) the xdh gene strengthens the structure of carrier pSUP202-s-ardh::xdh.
The plasmid pMD18-xdh that will contain target gene cuts with Xho I enzyme, and glue reclaims the purpose fragment; Carrier pSUP202-s-ardh::Km cuts rear with alkaline phosphatase CIAP dephosphorylation with Xho I enzyme; Get respectively xdh fragment and carrier pSUP202-s-ardh::Km enzyme and cut each 4 μ L of product, be connected each 1 μ L of buffer and T4 dna ligase with T4DNA and add simultaneously an eppendorf pipe, behind the mixing, 16 ℃ of connections are spent the night, Transformed E .coli JM109 competent cell, respectively with containing the screening of Amp and Km resistant panel, screening can not be carried out incubated overnight at the bacterium colony of Km resistant panel growth in the growth of Amp resistant panel, extract plasmid, cut with EcoR I enzyme, 37 ℃ of water-bath 2h, agarose gel electrophoresis is identified, can see that the 2500bp band occurs, enzyme be cut identified positive recombinant plasmid called after pSUP202-s-ardh::xdh (Figure 10).
Embodiment 4:xdh gene strengthens the acquisition of mutant CGMCC No.2709s-ardh::xdh NSAX31.
To contain the E.coli JM109 that knocks out mutational vector pSUP202-s-ardh::xdh and be used for three parent's joints as the donor bacterium, recipient bacterium is CGMCC No.2709s-ardh::Km mutantNSA18.Knock out mutational vector and enter CGMCC No.2709NSA18 under the help that helps bacterium pRK2013, the target gene fragment that will contain the xdh gene is incorporated on the karyomit(e) of CGMCCNo.2709NSA18.Screen three close zygotes by Cefotaxime, Km.
With donor bacterium E.coli JM109/pSUP202-s-ardh::xdh, help bacterium JM109/pRK2013 to be seeded in respectively to be added with penbritin, card to receive overnight incubation in the mycin LB substratum, recipient bacterium G.oxydans s-ardh::Km mutantNSA18 is seeded in G-Ara and cultivates 15～20h, A
660Value is to engage experiment at 0.6～1.0 o'clock; Press the receptor parent bacterium: help bacterium: the bacteria liquid of donor bacterium=3: 1: 3 is long-pending than collecting thalline, be receptor parent bacterium liquid 1.5mL, centrifugal collection thalline, outwell supernatant, after washing twice with physiological saline, outwell liquid, add 0.5mL and help bacterium liquid, add 1.5mL donor bacterium behind the centrifugal collection thalline, wash once with G-Ara behind the centrifugal collection thalline, outwell liquid, in remaining a small amount of substratum with cell micropipet mixing, transfer on the solid G-Ara substratum of added with antibiotic not, be inverted 30 ℃ of overnight incubation; The resistance that has with G.oxydans add on the recombinant plasmid with resistance, screen corresponding transformant; Three close zygomycetes body and function aseptic double-distilled waters of overnight incubation are washed from solid G-Ara substratum, be coated onto on the G-Ara flat board that adds cefotaxime acid, cultivated 2～4 days.
Picking can be containing Cefotaxime resistant panel growth can not be cultivated containing the bacterium colony that Cefotaxime and Km resistant panel grow, the centrifugal collection thalline of single bacterium colony culture, resuspended, add Proteinase K, behind 42 ℃ of 2h, boil 7min, 4 ℃ of centrifugal collection supernatants, be template to be detected, prepare simultaneously the template supernatant of CGMCC No.2709s-ardh::Kmmutant NSA18; With s-ardh L-fwd and xdh-rev and xdh-fwd and xdh-rev primer, carry out respectively pcr amplification, s-ardh L-fwd and xdh-rev amplification PCR product carry out sequencing analysis, evaluation through gene level, success obtains the CGMCC No.2709s-ardh::Km mutant NSA18 bacterial strain that xdh strengthens, i.e. CGMCCNo.2709s-ardh::xdh NSAX31 bacterial strain (Figure 11).
Embodiment 5:s-ardh gene knockout mutant transforms D-R alcohol and produces Xylitol.
Slant medium: glucose 30g/L, yeast extract paste 10g/L, extractum carnis 5g/L, agar 20g/L.
Shake-flask culture base: glucose 30g/L, yeast extract paste 25g/L, extractum carnis 5g/L, D-R alcohol 10g/L, KH
2PO
45g/L.
Then 30 ℃ of cultivation 24h on slant medium CGMCC No.2709 bacterial strain and mutant strain CGMCC No.2709s-ardh::Km NSA18 connect this bacterium of ring in the shake-flask culture base, cultivate 10h, shaking flask rotating speed 200r/min for 30 ℃.With the thalline of cultivating 24h in the centrifugal 10min of 8000r/min, and with the potassium phosphate buffer washed twice of 100mM pH6.0, collecting cell.Take by weighing in the D-R alcoholic solution that the wet cell of 1g after centrifugal add 10mL 30g/L (the cell addition is by the D-R alcoholic solution of every 100g cell transformation 1L 30g/L), under 30 ℃ of conditions, after reacting 9h under the 220rpm, add 30 ℃ of lower standing and reacting 27h of 5% ethanol, the amount of sampling and measuring substrate and product.Final CGMCC No.2709 bacterial strain can obtain Xylitol 14.6g/L, and Xylitol is 48.7% to the D-ara transformation efficiency; The NSA18 bacterial strain can obtain Xylitol 16.7g/L, and Xylitol is 55.7% (table 1) to the D-ara transformation efficiency.
The impact that table 1 s-ardh gene knockout produces Xylitol to catalysis D-R alcohol
As can be seen from Table 1, the conversion fluid of wild-type CGMCC No.2709 bacterial strain in reaction at the end, the 1.0g/L of D-R determining alcohol during from 9h rises to 13.7g/L, and the conversion fluid of s-ardh gene knock-out bacterial strain the D-R determining alcohol is constant reacting at the end, the s-ardh gene is destroyed and knock out in the transformant that conclusive evidence screens.
Embodiment 6:xdh gene strengthens mutant and transforms D-R alcohol product Xylitol.
Then 30 ℃ of cultivation 24h on slant medium CGMCC No.2709 bacterial strain and enhancing bacterial strain CGMCC No.2709s-ardh::xdh NSAX31 connect this bacterium of ring in the shake-flask culture base, cultivate 10h, shaking flask rotating speed 200r/min for 30 ℃.With the thalline of cultivating 24h in the centrifugal 10min of 8000r/min, and with the potassium phosphate buffer washed twice of 100mM pH6.0, collecting cell.Take by weighing in the D-R alcoholic solution that the wet cell of 1g after centrifugal add 10mL 30g/L (the cell addition is by the D-R alcoholic solution of every 100g cell transformation 1L 30g/L), under 30 ℃ of conditions, after reacting 9h under the 220rpm, add 30 ℃ of lower standing and reacting 27h of 5% ethanol, the amount of sampling and measuring substrate and product.Final NSAX18 bacterial strain can obtain Xylitol 28.7g/L, and Xylitol is to D (table 2).
Table 2 s-ardh gene knockout and xdh gene strengthen the impact that catalysis D-R alcohol is produced Xylitol
Claims (3)
1. the construction process of a Gluconobater oxydans genetic engineering strain is characterized in that the method comprises the steps:
(1) design of primers: the Gluconobacter oxydans 621H gene of announcing according to GenBank is two pairs of special primers of basic design, and primer is as follows:
s-ardh L-fwd：5’-TAT
GAATTCCCTCTTGAAAACCTATCATAGC-3’ EcoR I，
s-ardh L-rev：5’-CTGTTTATGTAAGC
CTCGAGAAACTTGAAGTCC-3’ Xho I，
s-ardh R-fwd：5’-AATAAACAAATAG
CTCGAGAAAATGGCCGGGAAG-3’Xho I，
s-ardh R-rev：5’-AT
GAATTCATGGCGACTGTCGAACTCAAG-3’ EcoR I；
(2) s-ardh L, s-ardh R gene cloning: by round pcr, take Gluconobacter oxydans strain gene group DNA as template, each 800bp sequence of s-ardh L and s-ardh R increases respectively;
(3) acquisition of resistance fragment Km: the card of announcing according to GenBank is received mycin resistant gene Km sequence, designs a pair of Auele Specific Primer km-fwd and km-rev, the complete CDs take pET28a (+) plasmid as template amplification Km, and primer is as follows:
km-fwd：5’-GGACTTCAAGTTT
CTCGAGGCTTACATAAACAG-3’ Xho I，
km-rev：5’-CTTCCCGGCCATTTT
CTCGAGCTATTTGTTTATT-3’Xho I，
Km-fwd and km-rev primer two ends add same restriction enzyme site Xho I and protection base, and underscore partly is restriction enzyme site, amplifies the 900bp sequence;
(4) structure of pMD18-KR: s-ardh R is connected by overlapping PCR method with the Km fragment, obtaining size is the fragment KR of 1700bp, be connected with the pMD18-T carrier, be converted among the competence E.coli JM109, obtain to contain the recombinant plasmid pMD18-KR of target gene by containing the screening of Amp and Km resistant panel;
(5) structure of pMD18-LKR: s-ardh L is connected by overlapping PCR method with the KR fragment, obtaining size is the fragment LKR of 2500bp, be connected with the pMD18-T carrier, be converted among the competence E.coli JM109, obtain to contain the recombinant plasmid pMD18-LKR of target gene by the LB plate screening that contains Amp and Km;
(6) structure of s-ardh gene knockout carrier pSUP202-s-ardh::Km: recombinant plasmid pMD18-LKR is cut with EcoR I enzyme; Carrier pSUP202 cuts the rear CIAP of using dephosphorylation with EcoR I enzyme; The carrier pSUP202 that LKR fragment after enzyme cut is connected with dephosphorylation connects with the T4 ligase enzyme, is converted among the competence E.coli JM109, obtains to contain the recombinant plasmid pSUP202-s-ardh::Km of target gene by the LB plate screening that contains Amp and Km;
(7) acquisition of s-ardh gene knockout mutant G.oxydans s-ardh::Km mutant NSA18: will contain the E.coli JM109 that knocks out mutational vector pSUP202-s-ardh::Km and be used for three parent's joints as the donor bacterium, recipient bacterium is G.oxydans; Knock out mutational vector and enter G.oxydans under the help that helps bacterium pRK2013, the target gene fragment that will contain the Km gene is incorporated on the karyomit(e) of G.oxydans, screens three close zygotes by Cefotaxime, Km;
(8) design of primers: the Gluconobacter oxydans 621H gene of announcing according to GenBank is two pairs of special primers of basic design, and primer is as follows:
xdh-fwd：5’-AGG
CTCGAGTCGAAGAAGTTTAAG-3’Xho I，
xdh-rev：5’-ATT
CTCGAGTCAACCGCCAGCAAT-3’Xho I；
(9) xdh gene cloning: by round pcr, take Gluconobacter oxydans strain gene group DNA as template, amplification 800bpxdh sequence;
(10) the xdh gene strengthens the structure of carrier pSUP202-s-ardh::xdh: the plasmid pMD18-xdh that will contain target gene cuts with Xho I enzyme, and glue reclaims the purpose fragment; Carrier pSUP202-s-ardh::Km cuts the rear CIAP of using dephosphorylation with Xho I enzyme; The carrier that purpose fragment after enzyme cut is connected with dephosphorylation connects with the T4 ligase enzyme, is converted among the competence E.coli JM109, obtains to contain the recombinant plasmid pSUP202-s-ardh::xdh of target gene by containing the screening of Amp and Km resistant panel;
(11) the xdh gene strengthens the acquisition of mutant G.oxydans s-ardh::xdh NSAX31: will contain the E.coli JM109 that knocks out mutational vector pSUP202-s-ardh::xdh and be used for three parent's joints as the donor bacterium, recipient bacterium is G.oxydanss-ardh::Km mutant NSA18; Knock out mutational vector and enter G.oxydansNSA18 under the help that helps bacterium pRK2013, the target gene fragment that will contain the xdh gene is incorporated on the karyomit(e) of G.oxydans NSA18; Screen three close zygotes by Cefotaxime, Km;
Described Gluconobater oxydans genetic engineering strain is disappearance s-ArDH gene, and the oxidizing glucose acidfast bacilli (Gluconobacter oxydans) that strengthens with the XDH gene in the position of s-ArDH gene.
2. the construction process of Gluconobater oxydans genetic engineering strain according to claim 1, it is characterized in that in the step (9), the method of xdh gene clone is: adopt round pcr, take Gluconobacter oxydans strain gene group DNA as template, carry out pcr amplification with primer xdh-fwd, xdh-rev, the PCR reaction conditions is: 10 * PCRbuffer5 μ L, Mg
2+2 μ L, dNTP 5 μ L, each 2 μ L of primer xdh-fwd and xdh-rev, exTaq DNApolymerase 1 μ L, genomic templates 1 μ L adds ddH
2O is 50 μ L to reacting cumulative volume; The PCR program is: 94 ℃ of denaturation 2min; 94 ℃ of sex change 30s, 53.6 ℃ of annealing 30s, 72 ℃ are extended 1min, circulate 30 times; 72 ℃ prolong 10min.
3. the construction process of Gluconobater oxydans genetic engineering strain according to claim 1, it is characterized in that in the step (11), three parents engage the method that strengthens: donor bacterium E.coli JM109/pSUP202-s-ardh::xdh, help bacterium JM109/pRK2013 are seeded in respectively overnight incubation in the LB substratum that is added with penbritin and Ka Na mycin, recipient bacterium G.oxydans s-ardh::Km mutant NSA18 is seeded in G-Ara and cultivates 15～20h, and the A660 value is to engage experiment at 0.6～1.0 o'clock; Press the receptor parent bacterium: help bacterium: the bacteria liquid of donor bacterium=3: 1: 3 is long-pending than collecting thalline, transfers on the solid G-Ara substratum of added with antibiotic not, is inverted 30 ℃ of overnight incubation; The resistance that has with G.oxydans add on the recombinant plasmid with resistance, screen corresponding transformant; Three close zygomycetes body and function aseptic double-distilled waters of overnight incubation are washed from solid G-Ara substratum, be coated onto on the G-Ara flat board that adds cefotaxime acid, cultivated 2～4 days, grow zygote and carry out the PCR checking.
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