High-level production of γ-aminobutyric acid via efficient co-expression of the key genes of glutamate decarboxylase system in Escherichia coli

Lili Yao; Changjiang Lyu; Yuting Wang; Sheng Hu; Weirui Zhao; Hongwei Cao; Jun Huang; Lehe Mei

doi:10.1016/j.engmic.2023.100077

High-level production of γ-aminobutyric acid via efficient co-expression of the key genes of glutamate decarboxylase system in Escherichia coli

Eng Microbiol. 2023 Feb 3;3(2):100077. doi: 10.1016/j.engmic.2023.100077. eCollection 2023 Jun.

Authors

Lili Yao^{1

2}, Changjiang Lyu², Yuting Wang², Sheng Hu³, Weirui Zhao³, Hongwei Cao¹, Jun Huang², Lehe Mei^{3

4}

Affiliations

¹ College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
² School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China.
³ School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China.
⁴ College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.

Abstract

Biosynthesis of the functional factor γ-aminobutyric acid (GABA) in bacteria involves two key proteins an intracellular glutamate decarboxylase (GadB) and a membrane-bound antiporter (GadC). Efficient co-expression of suitable GadB and GadC candidates is crucial for improving GABA productivity. In this study, gadB _ΔC11 of Lactiplantibacillus plantarum and gadC _ΔC41 of Escherichia coli were inserted into the designed double promoter (P _T7lac and P _BAD ) expression system. Then, E. coli Lemo21(DE3) was chosen as the host to minimize the toxic effects of GadC_ΔC41 overexpression. Furthermore, a green and high-efficiency GABA synthesis system using dormant engineered Lemo21(DE3) cells as biocatalysts was developed. The total GABA yield reached 829.08 g/L with a 98.7% conversion ratio within 13 h, when engineered E. coli Lemo21(DE3) cells were concentrated to an OD₆₀₀ of 20 and reused for three cycles in a 3 M L-glutamate solution at 37 °C, which represented the highest GABA productivity ever reported. Overall, expanding the active pH ranges of GadB and GadC toward physiological pH and employing a tunable expression host for membrane-bound GadC production is a promising strategy for high-level GABA biosynthesis in E. coli.

Keywords: Antiporter; E. coli; Glutamate decarboxylase; Whole-cell biocatalysts; γ-Aminobutyric acid.