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Improvement of l-Leucine Production in Corynebacterium glutamicum by Altering the Redox Flux.


ABSTRACT: The production of l-leucine was improved by the disruption of ltbR encoding transcriptional regulator and overexpression of the key genes (leuAilvBNCE) of the l-leucine biosynthesis pathway in Corynebacterium glutamicum XQ-9. In order to improve l-leucine production, we rationally engineered C. glutamicum to enhance l-leucine production, by improving the redox flux. On the basis of this, we manipulated the redox state of the cells by mutating the coenzyme-binding domains of acetohydroxyacid isomeroreductase encoded by ilvC, inserting NAD-specific leucine dehydrogenase, encoded by leuDH from Lysinibacillus sphaericus, and glutamate dehydrogenase encoded by rocG from Bacillus subtilis, instead of endogenous branched-chain amino acid transaminase and glutamate dehydrogenase, respectively. The yield of l-leucine reached 22.62 ± 0.17 g·L-1 by strain ?LtbR-acetohydroxyacid isomeroreductase (AHAIR)M/ABNCME, and the concentrations of the by-products (l-valine and l-alanine) increased, compared to the strain ?LtbR/ABNCE. Strain ?LtbR-AHAIRMLeuDH/ABNCMLDH accumulated 22.87±0.31 g·L-1 l-leucine, but showed a drastically low l-valine accumulation (from 8.06 ± 0.35 g·L-1 to 2.72 ± 0.11 g·L-1), in comparison to strain ?LtbR-AHAIRM/ABNCME, which indicated that LeuDH has much specificity for l-leucine synthesis but not for l-valine synthesis. Subsequently, the resultant strain ?LtbR-AHAIRMLeuDHRocG/ABNCMLDH accumulated 23.31 ± 0.24 g·L-1 l-leucine with a glucose conversion efficiency of 0.191 g·g-1.

SUBMITTER: Wang YY 

PROVIDER: S-EPMC6515235 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Improvement of l-Leucine Production in <i>Corynebacterium glutamicum</i> by Altering the Redox Flux.

Wang Ying-Yu YY   Zhang Feng F   Xu Jian-Zhong JZ   Zhang Wei-Guo WG   Chen Xiu-Lai XL   Liu Li-Ming LM  

International journal of molecular sciences 20190424 8


The production of l-leucine was improved by the disruption of <i>ltbR</i> encoding transcriptional regulator and overexpression of the key genes (<i>leuAilvBNCE</i>) of the l-leucine biosynthesis pathway in <i>Corynebacterium glutamicum</i> XQ-9. In order to improve l-leucine production, we rationally engineered <i>C. glutamicum</i> to enhance l-leucine production, by improving the redox flux. On the basis of this, we manipulated the redox state of the cells by mutating the coenzyme-binding doma  ...[more]

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2016-01-26 | GSE77189 | GEO