摘要
The microbial production of D-lysine to replace chemical approach has gained great interest with the rising concerns over the environment.Here,we employed recombinant E.coli strain BL21-LYR with lysine racemase and strain BL-22A-RB-YB with L-lysine monooxygenase and 5-aminovaleramide amidohydrolase to establish a two-strain coupling whole-cell bioconversion system for D-lysine production from L-lysine.To improve the optical purity of D-lysine,the optimal reaction condition for resolution of DL-lysine after the racemization was investigated.The specificity of BL-22A-RB-YB for L^-lysine and the effects of reaction condition on bioconversion efficiency of whole-cell were accordingly determined.Under the optimal condition,a maximum 53.5 g·L^-1 D-lysine and 48.2 g·L^-15-AVA were obtained with yield of 47.4%and 42.3%,respectively,by the microbial racemization and asymmetric degradation process.The final D-lysine enantiomeric excess was over 99%.Meanwhile,a valuable compound 5-aminovaleric acid was synthesized with the production of D-lysine,indicating the economic feasibility of the two-strain coupling system.
基金
financial supports from the National Natural Science Foundation of China(Grant No.21908099)
the National Key Research and Development Program of China(Grant No.2016YFA0204300)
Key Research and Development Program(Social Development)Project Jiangsu Province(Grant No.BE2018730)
the Natural Science Research Projects of Colleges and Universities in Jiangsu Province(Grant No.18KJB530009)
the Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture(Grant No.XTB1802,Grant No.XTE1846)。