Tianjin University of Science and Technology

Zhejiang Zhenyuan Biotech Co. Ltd.

Xixian Xie

Heyun Wu

Ning Chen

Qian Ma

Yanjun Li

Qingyang Xu

Xiaoguang Fan

Yue Zhang

Jie Ma

Qiang Li

Chenglin Zhang

Weiming Fan

Jianqing Tu

Yanna Chen

Daoguang Tian

Wei Jiang

Xiaoqian Liu

Yanan Hao

Jiachu Wang

Faqing Wu

Xuejiao Wu

Fangqing Yan

Guoliang Li

Hongchao Zhang

A genetically engineered strain having high-yield of L-valine is disclosed. Starting fromW3110, an acetolactate synthase gene alsS ofis inserted into a genome thereof and overexpressed; a ppGpp 3'-pyrophosphate hydrolase mutant R290E/K292D gene spoTM ofis 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 ofreplaces a branched chain amino acid transaminase gene ilvE of; and an acetohydroxy acid isomeroreductase mutant L67E/R68F/K75E gene ilvCM replaces the native acetohydroxy acid isomeroreductase gene ilvC of. 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.

Genetically engineered strain with high yield of L-valine and method for producing L-valine by fermentation

A genetically engineered bacterium includes a genome of theand a mutant encoding gene hisG* of aATP 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 theis further increased on the genome to enhance a terminal synthetic route of histidine; an encoding gene lysE from an arginine/lysine transportprotein of theis 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 ofis further integrated to the genome and strongly expressed to promote generation of histidine.

Genetically engineered bacterium for producing L-histidine and use thereof

The present disclosure relates to the field of genetic engineering, especially relates to a xylose-induced genetically engineered bacteria used for producing ectoine as well as a construction method and use thereof. The genetically engineered bacteria is constructed by heterologously expressing the ectABC gene cluster fromon thechromosome, using the promoter of xylose transporter coding gene xylF to control the RNA polymerase from T7 bacteriophage, reconstructing a synthesis pathway of ectoine and constructing a plasmid-free system, and enhancing the expression of target genes by a strong promoter T7; the yield of ectoine reached 12-16 g/L after 20-28 h fermentation in shake flask, and reached 35-50 g/L after 24-40 h fermentation in a 5 L fermentor.

Xylose-induced genetically engineered bacteria used for producing ectoine and use thereof

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 ofprompted by strong promoter Pto 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 Pon 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 1.5 g/L/h respectively which is the highest level of fermentative producing uridine reported at present.

Genetically engineered bacterium used for producing uridine with high-yield

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Tianjin, China

Xixian Xie