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Whole-cell conversion of L-glutamic acid into γ-aminobutyric acid via an engineered strain overexpressing glutamate decarboxylase from Priestia flexa
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  • Zhongmei Liu,
  • Yiwei Zhang,
  • Wenjing Cui,
  • Zhemin Zhou
Zhongmei Liu
Jiangnan University Key Laboratory of Industrial Biotechnology Ministry of Education

Corresponding Author:[email protected]

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Yiwei Zhang
Jiangnan University Key Laboratory of Industrial Biotechnology Ministry of Education
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Wenjing Cui
Jiangnan University Key Laboratory of Industrial Biotechnology Ministry of Education
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Zhemin Zhou
Jiangnan University Key Laboratory of Industrial Biotechnology Ministry of Education
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Abstract

Gamma-aminobutyric acid (GABA) is widely applied in the food and pharmaceutical industries, and glutamate decarboxylase (GAD) is the core enzyme for the biosynthesis of GABA. GAD exhibits high activity but poor stability under acidic conditions, and low activity under neutral conditions. In this study, GAD from Priestia flexa ( PfGAD) with high activity was screened out and characterized, and a variant with significantly improved stability was obtained through molecular modification strategies. We constructed an engineered strain that coexpressed PfGAD and a transporter protein for GABA and L-glutamic acid. Furthermore, the consumption of GABA was suppressed by knocking out the pepD gene, confirming a novel downstream metabolic pathway of GABA in Escherichia coli. The continuous accumulation of GABA in the engineered strain led to a yield of 154.7 g·L -1, with a conversation rate of 100%, meanwhile the cell growth was remained normal. The problem of the trade-off between cell growth and GABA accumulation was solved, which was one of the urgent problems according to previous reports. Our study provides important insights into the optimization of GABA production through enzyme engineering and strain modification, which could have significant implications for the industrial application of GABA.
02 Feb 2024Review(s) Completed, Editorial Evaluation Pending
02 Feb 2024Editorial Decision: Revise Major
19 Feb 20241st Revision Received
21 Feb 2024Submission Checks Completed
21 Feb 2024Assigned to Editor
22 Feb 2024Reviewer(s) Assigned
01 Mar 2024Review(s) Completed, Editorial Evaluation Pending