title: Improvement of L-valine production at high temperature in Brevibacterium flavum by overexpressing ilvEBNrC genes.
abstract: Brevibacterium flavum ATCC14067 was engineered for L: -valine production by overexpression of different ilv genes; the ilvEBN(r)C genes from B. flavum NV128 provided the best candidate for L: -valine production. In traditional fermentation, L: -valine production reached 30.08 ± 0.92 g/L at 31°C in 72 h with a low conversion efficiency of 0.129 g/g. To further improve the L: -valine production and conversion efficiency based on the optimum temperatures of L: -valine biosynthesis enzymes (above 35°C) and the thermotolerance of B. flavum, the fermentation temperature was increased to 34, 37, and 40°C. As a result, higher metabolic rate and L: -valine biosynthesis enzymes activity were obtained at high temperature, and the maximum L: -valine production, conversion efficiency, and specific L: -valine production rate reached 38.08 ± 1.32 g/L, 0.241 g/g, and 0.133 g g(-1) h(-1), respectively, at 37°C in 48 h fermentation. The strategy for enhancing L: -valine production by overexpression of key enzymes in thermotolerant strains may provide an alternative approach to enhance branched-chain amino acids production with other strains.
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University, 1800# Lihu Road, Wuxi, 214122, JiangSu Province, People's Republic of China. houxiaohu828@163.com
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Hou
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Ge
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.forename: He
authors.initials: H
authors.lastname: Qian
authors.forename: Weiguo
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D040142:Brevibacterium flavum / Q000235:genetics / Q000378:metabolism*; D004798:Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D005798:Genes, Bacterial; D006358:Hot Temperature; D008969:Molecular Sequence Data; D014633:Valine / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D004798:Enzymes; D014633:Valine