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Blocking the 2,3-butanediol synthesis pathway of Klebsiella pneumoniae resulted in L-valine production

Wang, Qinghui; Gu, Jinjie; Shu, Lin; Jiang, Weiyan; Mojovic, Ljiljana; Knezevic-Jugovic, Zorica; Shi, Jiping; ... Hao, Jian; + view all (2022) Blocking the 2,3-butanediol synthesis pathway of Klebsiella pneumoniae resulted in L-valine production. World Journal of Microbiology and Biotechnology , 38 (5) , Article 81. 10.1007/s11274-022-03266-9. Green open access

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Abstract

Klebsiella pneumoniae is a 2,3-butanediol producing bacterium. Nevertheless, a design and construction of L-valine production strain was studied in this paper. The first step of 2,3-butanediol synthesis and branched-chain amino acid synthesis pathways share the same step of α-acetolactate synthesis from pyruvate. However, the two pathways are existing in parallel and do not interfere with each other in the wild-type strain. A knockout of budA blocked the 2,3-butanediol synthesis pathway and resulted in the L-valine production. The budA coded an α-acetolactate decarboxylase and catalyzed the acetoin formation from α-acetolactate. Furthermore, blocking the lactic acid synthesis by knocking out of ldhA, which is encoding a lactate dehydrogenase, improved the L-valine synthesis. 2-Ketoisovalerate is the precursor of L-valine, it is also an intermediate of the isobutanol synthesis pathway, while indole-3-pyruvate decarboxylase (ipdC) is responsible for isobutyraldehyde formation from 2-ketoisovalerate. Production of L-valine has been improved by knocking out of ipdC. On the other side, the ilvE, encoding a transaminase B, reversibly transfers one amino group from glutamate to α-ketoisovalerate. Overexpression of ilvE exhibited a distinct improvement of L-valine production. The brnQ encodes a branched-chain amino acid transporter, and L-valine production was further improved by disrupting brnQ. It is also revealed that weak acidic and aerobic conditions favor L-valine production. Based on these findings, L-valine production by metabolically engineered K. pneumonia was examined. In fed-batch fermentation, 22.4 g/L of L-valine was produced by the engineered K. pneumoniae ΔbudA-ΔldhA-ΔipdC-ΔbrnQ-ilvE after 55 h of cultivation, with a substrate conversion ratio of 0.27 mol/mol glucose.

Type: Article
Title: Blocking the 2,3-butanediol synthesis pathway of Klebsiella pneumoniae resulted in L-valine production
Location: Germany
Open access status: An open access version is available from UCL Discovery
DOI: 10.1007/s11274-022-03266-9
Publisher version: https://doi.org/10.1007/s11274-022-03266-9
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: 2,3-Butanediol, Klebsiella pneumoniae, L-valine, brnQ, ilvE, ipdC
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Biochemical Engineering
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10148080
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