Institute of Biotechnology 2, Forschungszentrum Jülich, 52425, Jülich, Germany.
J Ind Microbiol Biotechnol. 2010 Mar;37(3):263-70. doi: 10.1007/s10295-009-0669-x. Epub 2009 Dec 11.
L-valine biosynthesis was analysed by comparing different plasmids in pyruvate-dehydrogenase-deficient Corynebacterium glutamicum strains in order to achieve an optimal production strain. The plasmids contained different combinations of the genes ilvBNCDE encoding for the L-valine forming pathway. It was shown that overexpression of the ilvBN genes encoding acetolactate synthase is obligatory for efficient pyruvate conversion and to prevent L-alanine as a by-product. In contrast to earlier studies, overexpression of ilvE encoding transaminase B is favourable in pyruvate-dehydrogenase-negative strains. Its amplification enhanced L-valine formation and avoided extra- and intracellular accumulation of ketoisovalerate.
为了获得最佳生产菌株，通过比较丙酮酸脱氢酶缺陷型谷氨酸棒杆菌中不同质粒，分析 L-缬氨酸生物合成。这些质粒包含编码 L-缬氨酸形成途径的 ilvBNCDE 基因的不同组合。结果表明，乙酰乳酸合酶编码基因 ilvBN 的过表达对于有效的丙酮酸转化和防止 L-丙氨酸作为副产物是必需的。与早期的研究不同，在丙酮酸脱氢酶阴性菌株中，编码转氨酶 B 的 ilvE 的过表达是有利的。其扩增增强了 L-缬氨酸的形成，并避免了酮异戊酸的细胞内外积累。
