Abstract: A genetically engineered strain having high-yield of L-valine is disclosed. Starting from Escherichia coli W3110, an acetolactate synthase gene alsS of Bacillus subtilis is inserted into a genome thereof and overexpressed; a ppGpp 3?-pyrophosphate hydrolase mutant R290E/K292D gene spoTM of Escherichia coli is inserted into the genome and overexpressed; a lactate dehydrogenase gene ldhA, a pyruvate formate lyase I gene pflB, and genes frdA, frdB, frdC, frdD of four subunits of fumaric acid reductase are deleted from the genome; a leucine dehydrogenase gene bcd of Bacillus subtilis replaces a branched chain amino acid transaminase gene ilvE of Escherichia coli; and an acetohydroxy acid isomeroreductase mutant L67E/R68F/K75E gene ilvCM replaces the native acetohydroxy acid isomeroreductase gene ilvC of Escherichia coli. Furthermore, the L-valine fermentation method is improved by using a two-stage dissolved oxygen control. The L-valine titer and the sugar-acid conversion rate are increased.

Abstract: A genetically engineered bacterium includes a genome of the Eschericia coli and a mutant encoding gene hisG* of a Corynebacterium glutamicum ATP phosphoribosyl transferase HisG on the genome, and the gene hisG* is strongly expressed to enhance activity of a key enzyme HisG for histidine synthesis. The gene hisG* has a nucleotide sequence as shown in SEQ ID NO: 1; a copy number of histidine operon genes hisDBCHAFI of the Eschericia coli is further increased on the genome to enhance a terminal synthetic route of histidine; an encoding gene lysE from an arginine/lysine transportprotein of the Corynebacterium glutamicum is further integrated to the genome and strongly expressed to promote the intracellular histidine secrete to the extracellular space; and an encoding gene rocG of glutamate dehydrogenase of Bacillus subtilis is further integrated to the genome and strongly expressed to promote generation of histidine.

Abstract: A genetically engineered strain having high-yield of L-valine is disclosed. Starting from Escherichia coli W3110, an acetolactate synthase gene alsS of Bacillus subtilis is inserted into a genome thereof and overexpressed; a ppGpp 3?-pyrophosphate hydrolase mutant R290E/K292D gene spoTM of Escherichia coli is inserted into the genome and overexpressed; a lactate dehydrogenase gene ldhA, a pyruvate formate lyase I gene pflB, and genes frdA, frdB, frdC, frdD of four subunits of fumaric acid reductase are deleted from the genome; a leucine dehydrogenase gene bcd of Bacillus subtilis replaces a branched chain amino acid transaminase gene ilvE of Escherichia coli; and an acetohydroxy acid isomeroreductase mutant L67E/R68F/K75E gene ilvCM replaces the native acetohydroxy acid isomeroreductase gene ilvC of Escherichia coli. Furthermore, the L-valine fermentation method is improved by using a two-stage dissolved oxygen control. The L-valine titer and the sugar-acid conversion rate are increased.

Abstract: Disclosed are gene engineering bacteria for producing L-arginine and a construction method and an application of the gene engineering bacteria. According to the method, genes encoding a carbamoyl phosphate synthetase and a gene encoding an L-arginine biosynthesis pathway enzyme are integrated into Escherichia coli; the present invention has analyzed and reconstructed the arginine synthetic pathway and the metabolic flow related to arginine in the entire amino acid metabolic network in E. coli and finally obtained a genetically engineered bacterial strain which has a clear genetic background, carries no plasmids, undergoes no mutagenesis and is capable of stably and efficiently producing L-arginine.

Abstract: A genetically engineered bacterium includes a genome of the Eschericia coli and a mutant encoding gene hisG* of a Corynebacterium glutamicum ATP phosphoribosyl transferase HisG on the genome, and the gene hisG* is strongly expressed to enhance activity of a key enzyme HisG for histidine synthesis. The gene hisG* has a nucleotide sequence as shown in SEQ ID NO: 1; a copy number of histidine operon genes hisDBCHAFI of the Eschericia coli is further increased on the genome to enhance a terminal synthetic route of histidine; an encoding gene lysE from an arginine/lysine transportprotein of the Corynebacterium glutamicum is further integrated to the genome and strongly expressed to promote the intracellular histidine secrete to the extracellular space; and an encoding gene rocG of glutamate dehydrogenase of Bacillus subtilis is further integrated to the genome and strongly expressed to promote generation of histidine.

Abstract: The present disclosure relates to a genetically engineered strain with high production of uridine and its construction method and application. The strain was constructed as follows: heterologously expressing pyrimidine nucleoside operon sequence pyrBCAKDFE (SEQ ID NO:1) on the genome of E coli prompted by strong promoter Ptrc to reconstruct the pathway of uridine synthesis; overexpressing the autologous prsA gene coding PRPP synthase by integration of another copy of prsA gene promoted by strong promoter Ptrc on the genome; deficiency of uridine kinase, uridine phosphorylase, ribonucleoside hydrolase, homoserine dehydrogenase I and ornithine carbamoyltransferase. When the bacteria was used for producing uridine, 40-67 g/L uridine could be obtained in a 5 L fermentor after fermentation for 40-70 h using the technical scheme provided by the disclosure with the maximum productivity of 0.15-0.25 g uridine/g glucose and 1.

Abstract: The present disclosure relates to a genetically engineered strain with high production of uridine and its construction method and application. The strain was constructed as follows: heterologously expressing pyrimidine nucleoside operon sequence pyrBCAKDFE (SEQ ID NO:1) on the genome of E coli prompted by strong promoter Ptrc to reconstruct the pathway of uridine synthesis; overexpressing the autologous prsA gene coding PRPP synthase by integration of another copy of prsA gene promoted by strong promoter Ptrc on the genome; deficiency of uridine kinase, uridine phosphorylase, ribonucleoside hydrolase, homoserine dehydrogenase I and ornithine carbamoyltransferase. When the bacteria was used for producing uridine, 40-67 g/L uridine could be obtained in a 5 L fermentator after fermentation for 40-70 h using the technical scheme provided by the discloure with the maximum productivity of 0.15-0.25 g uridine/g glucose and 1.