7 results about "Alanine racemase" patented technology

The invention discloses a genetically engineered bacterium for high yield of L-alanine as well as a construction method and application of the genetically engineered bacterium, a dominant strain is obtained by knocking out an alanine racemase gene dadX and integrating coding sequences of alanine dehydrogenase from different sources, and the shake flask yield is 10.8 g / L; the activity of a corresponding mutant M18L / E75A / A78S / I266V is 4.3 times that of a wild type; 6 by-product related genes are knocked out, meanwhile, a multi-copy strain integrated with alanine dehydrogenase is constructed, and the yield of E.coli A-LB6 in a 5L fermentation tank is increased to 133.3 g / L. Through a dynamic regulation and control strategy, an oxygen-sensitive promoter Pomp * is adopted to replace a phosphoenolpyruvate carboxylase promoter, so that succinic acid byproducts are reduced by 85.8%, and the yield reaches 143.5 g / L after 48 hours of aerobic and anaerobic two-stage fermentation. And finally, by regulating and controlling the ATP synthetase gene cluster atp promoter, the yield of L-alanine in a 50 L fermentation tank reaches 151.3 g / L, and the saccharic acid conversion rate reaches 95.2%. The combination of polygene knockout and dynamic metabolism regulation effectively enhances the biosynthesis ability of alanine, and provides an efficient engineering strain for industrial production.

The present disclosure provides recombinant Staphylococcus bacterium (e.g. S. epidermidis) that are dependent on D-alanine for growth. In one aspect, the disclosure features a recombinant Staphylococcus bacterium comprising two inactivated alanine racemase genes (Δalr1 Δalr2); and an inactivated D-alanine aminotransferase (dat) gene. In another aspect, the disclosure features a method of making the recombinant Staphylococcus bacterium. In another aspect, the disclosure features a method of treating or preventing a rash in a subject, comprising administering to the subject a population of the recombinant Staphylococcus bacterium of any one of the aspects or embodiments described herein, in an effective amount to treat or prevent the rash in the subject.

The present invention discloses an L-alanine-producing genetically engineered strain, as well as a method of construction and use thereof, and pertains to the field of bioengineering. According to the present invention, through enhancing the glycolysis pathway or / and introducing a gene for thermostable alanine dehydrogenase, a genetically engineered strain capable of high-yield production of alanine under a high temperature condition of 42° C. to 55° C. can be constructed. Moreover, through knocking out alanine racemase genes, optical purity of L-alanine can be significantly increased. When the original strain possesses a lactate synthesis pathway, blocking this lactate synthesis pathway can augment the proportion of a pyruvate synthesis pathway, resulting in an additionally increased yield of L-alanine. The present invention overcomes the problems of fermentation at a low temperature, high cost and the like, which arise from the use of conventional L-alanine production techniques, enables production of L-alanine by fermentation at a high temperature of 42° C. to 55° C. with a yield of 95 g / L or higher, and is of high value to industrial application.

The invention discloses a method for biosynthesizing gamma-polyglutamic acid without antibiotics, which particularly comprises the following steps: knocking out an alr gene for coding alanine racemase on a chassis strain corynebacterium glutamicum genome to construct alanine auxotroph cells, transferring alr to an expression plasmid pZM1 to construct a complementary plasmid, and successfully constructing a plasmid expression system without antibiotic addition; on the basis, gamma-polyglutamic acid degrading enzyme genes pgdS and pgsBCA derived from bacillus subtilis are subjected to tandem expression, and a dual-module formed by gamma-polyglutamic acid synthetase and degrading enzyme is further subjected to metabolism regulation by screening a promoter, RBS and a protein degradation tag at three levels of transcription, translation and post-translation modification. Under the regulation and control of a PtacM-UTR2-DAS + 8 element combination, the efficient synthesis of the gamma-polyglutamic acid is realized, the yield can reach 24.2 g.L <-1 >, and the production intensity is 0.55 g.L <-1 >. H <-1 >. And a gamma-polyglutamic acid production process without antibiotic addition is successfully constructed.

This invention provides recombinant Staphylococcus bacteria (e.g., Staphylococcus epidermidis) whose growth is dependent on D-alanine, and a method for producing recombinant Staphylococcus bacteria. [Solution] In one embodiment, this specification features recombinant Staphylococcus bacteria comprising two inactivated alanine racemase genes (Δalr1Δalr2); and an inactivated D-alanine aminotransferase (dat) gene.

The application discloses a mutant D-amino acid dehydrogenase and a method for preparing D-phenylalanine through a multi-enzyme cascade, wherein the mutant D-amino acid dehydrogenase is obtained by site-directed mutagenesis of wild-type amino acid dehydrogenase of symbiotic bacillus licheniformis; the multi-enzyme cascade preparation method is to use cheap L-phenylalanine as raw material, first obtain DL-phenylalanine through catalysis of alanine racemase, and then convert L-phenylalanine into D-phenylalanine through L-amino acid deaminase, mutant D-amino acid dehydrogenase and formic acid dehydrogenase. The concentration of D-phenylalanine product obtained by the method reaches 80-120 g / L, and the conversion rate can reach 95-98 %, so that the method not only shortens the production cycle and has high product concentration, but also is easy to industrialize.

To provide recombinant Staphylococcus bacteria (e.g., S. epidermidis) that are dependent on D-alanine for growth. [Solution] In one aspect, the Disclosure features recombinant Staphylococcus bacteria comprising two inactivated alanine racemase genes (Δalr1Δalr2); and an inactivated D-alanine aminotransferase (dat) gene. In another aspect, the Disclosure features a method for producing recombinant Staphylococcus bacteria. In another aspect, the Disclosure provides a method for treating or preventing a rash in a subject, the method comprising the step of administering to the subject an amount effective to treat or prevent a rash in the subject, which is one of the aspects or embodiments described herein.