谷氨酸棒杆菌ilvE基因的敲除对相关氨基酸合成的影响

Effect of ilvE Gene Knockout on Amino Acids Synthesis of Corynebacterium glutamicum

L-缬氨酸是谷氨酸棒杆菌SYPS-062发酵生产L-丝氨酸的主要副产物。为减少L-缬氨酸的积累,利用基因重组技术敲除SYPS-062转氨酶B编码基因ilvE内部的987 bp核苷酸序列,构建了ilvE基因缺失突变株SYPS-062△ilvE。研究表明,重组菌ilvE基因的缺失直接导致了分支氨基酸(Val、Ile、Leu)的合成能力的降低,影响了菌体的生长,其中Ile成为生长限制性因子,在培养基中添加分支氨基酸能明显促进其生长。重组菌培养96 h,发酵液中L-缬氨酸含量低于0.5 g/L,与出发菌株相比,其生成率降低90%。

L-Valine was the main by-product during the production of L-Serine by Corynbacterium glutamicum SYPS-062. In order to study the effect of ilvE deletion on the accumulation of L-Valine, ilvE gene deficient mutant strain Corynbacterium glutamicum SYPS-062 A ilvE was constructed by homologous recombination. The central fragment encoding 987 bp nucleotides of ilvE was deleted. The growth of theAilvE phenotype on the chemical defined medium was significantly retarded due to the reduced biosynthesis capability of branch-chain amino acids （ Val, lie, Leu ） . However, growth condition of the ilvE deleted mutant can be significantly improved when supplemented with 250 mg/L branched- chain amino acids. L-Ile was the limiting factor for SYPS-O62AilvE growth. The results suggested that the productivity of L-Valine decreased 90% compared with the wild type strain, the concentration of L-Valine was decreased to 0.5 g/L in the 96 h culture.