GENETICALLY ENGINEERED STRAIN HAVING HIGH-YIELD OF L-VALINE AND METHOD FOR PRODUCING L-VALINE BY FERMENTATION

摘要

A genetically engineered strain having high-yield of L-valine. Starting from Escherichia coli W3110, the acetolactate synthase gene alsS of Bacillus subtilis is integrated and strongly expressed on a genome thereof; the Escherichia coli ppGpp 3'-pyrophosphate hydrolase mutant R290E/K292D gene spoT is integrated and strongly expressed on the genome thereof; the lactate dehydrogenase gene ldhA, the pyruvate formate lyase I gene pflB, and the genes frdA, frdB, frdC, frdD of four subunits of the fumaric acid reductase on the genome thereof is knocked out; the branched chain amino acid transaminase gene ilvE of Escherichia coli is replaced with the leucine dehydrogenase gene bcd of Bacillus subtilis; and the acetylhydroxylate isomerase reductase gene ilvC of Escherichia coli is replaced with the encoding gene of the mutant L67E/R68F/K75E. Furthermore, the L-valine fermentation method is improved, and the L-valine yield and the sugar acid conversion rate are increased by using a two-stage oxygen dissolution control.