Reducing lactate secretion by ldhA Deletion in L-glutamate- producing strain Corynebacterium glutamicum GDK-9

Brazilian Journal of Microbiology

Dalong Zhang²  Dan Guan¹  Jingbo Liang²  Chunqian Guo²  Xixian Xie²  Chenglin Zhang²  Qingyang Xu²  Ning Chen² 

[1] ,Tianjin University of Science and Technology College of Biotechnology Tianjin,P.R. China

关键词: Corynebacterium glutamicum;    L-glutamate;    L-lactate dehydrogenase;    gene knockout;    fermentation;   

DOI  :  10.1590/S1517-83822014000400044

来源: SciELO

【 摘 要 】

L-lactate is one of main byproducts excreted in to the fermentation medium. To improve L-glutamate production and reduce L-lactate accumulation, L-lactate dehydrogenase-encoding gene ldhA was knocked out from L-glutamate producing strain Corynebacterium glutamicum GDK-9, designated GDK-9ΔldhA. GDK-9ΔldhA produced approximately 10.1% more L-glutamate than the GDK-9, and yielded lower levels of such by-products as α-ketoglutarate, L-lactate and L-alanine. Since dissolved oxygen (DO) is one of main factors affecting L-lactate formation during L-glutamate fermentation, we investigated the effect of ldhA deletion from GDK-9 under different DO conditions. Under both oxygen-deficient and high oxygen conditions, L-glutamate production by GDK-9ΔldhA was not higher than that of the GDK-9. However, under micro-aerobic conditions, GDK-9ΔldhA exhibited 11.61% higher L-glutamate and 58.50% lower L-alanine production than GDK-9. Taken together, it is demonstrated that deletion of ldhA can enhance L-glutamate production and lower the unwanted by-products concentration, especially under micro-aerobic conditions.

【 授权许可】

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