3 results about "Alanine racemase" patented technology

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.

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.