Metabolic Engineering of Enterobacter aerogenes for Improved 2,3-Butanediol Production by Manipulating NADH Levels and Overexpressing the Small RNA RyhB

• Published in: Frontiers in microbiology Vol. 12
• Main Authors: Wu, Yan, Chu, Wanying, Yang, Jiayao, Xu, Yudong, Shen, Qi, Yang, Haoning, Xu, Fangxu, Liu, Yefei, Lu, Ping, Jiang, Ke, Zhao, Hongxin
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 08.10.2021
• Subjects: 2,3-butanediol; Enterobacter aerogenes; lactate dehydrogenase; Microbiology; NADH dehydrogenase; small RNA RyhB
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2021.754306

Biotechnological production of 2,3-butanediol (2,3-BD), a versatile platform bio-chemical and a potential biofuel, is limited due to by-product toxicity. In this study, we aimed to redirect the metabolic flux toward 2,3-BD in Enterobacter aerogenes ( E. aerogenes ) by increasing the intracellular NADH pool. Increasing the NADH/NAD + ratio by knocking out the NADH dehydrogenase genes ( nuoC / nuoD ) enhanced 2,3-BD production by up to 67% compared with wild-type E. aerogenes . When lactate dehydrogenase ( ldh ) was knocked out, the yield of 2,3-BD was increased by 71.2% compared to the wild type. Metabolic flux analysis revealed that upregulated expression of the sRNA RyhB led to a noteworthy shift in metabolism. The 2,3-BD titer of the best mutant Ea-2 was almost seven times higher than that of the parent strain in a 5-L fermenter. In this study, an effective metabolic engineering strategy for improved 2,3-BD production was implemented by increasing the NADH/NAD + ratio and blocking competing pathways.