State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
Ningxia Key Laboratory for the Development and Application of Microbial Resources in Extreme Environments, North Minzu University, Yinchuan, 750021, China.
Microb Cell Fact. 2021 Aug 4;20(1):153. doi: 10.1186/s12934-021-01646-8.
Gamma-aminobutyric acid (GABA) is an important bio-product used in pharmaceuticals and functional foods and as a precursor of the biodegradable plastic polyamide 4. Glutamate decarboxylase (GAD) converts L-glutamate (L-Glu) into GABA via decarboxylation. Compared with other methods, develop a bioconversion platform to produce GABA is of considerable interest for industrial use.
Three GAD genes were identified from three Bacillus strains and heterologously expressed in Escherichia coli BL21 (DE3). The optimal reaction temperature and pH values for three enzymes were 40 °C and 5.0, respectively. Of the GADs, GADZ11 had the highest catalytic efficiency towards L-Glu (2.19 mM s). The engineered E. coli strain that expressed GADZ11 was used as a whole-cell biocatalyst for the production of GABA. After repeated use 14 times, the cells produced GABA with an average molar conversion rate of 98.6% within 14 h.
Three recombinant GADs from Bacillus strains have been conducted functional identification. The engineered E. coli strain heterologous expressing GADZ1, GADZ11, and GADZ20 could accomplish the biosynthesis of L-Glu to GABA in a buffer-free reaction at a high L-Glu concentration. The novel engineered E. coli strain has the potential to be a cost-effective biotransformation platform for the industrial production of GABA.
γ-氨基丁酸（GABA）是一种重要的生物产物，用于制药和功能性食品，并作为可生物降解塑料聚酰胺 4 的前体。谷氨酸脱羧酶（GAD）通过脱羧将 L-谷氨酸（L-Glu）转化为 GABA。与其他方法相比，开发用于工业生产的生物转化平台来生产 GABA 具有相当大的兴趣。
从三种芽孢杆菌菌株中鉴定出三种 GAD 基因，并在大肠杆菌 BL21（DE3）中异源表达。三种酶的最佳反应温度和 pH 值分别为 40°C 和 5.0。在 GAD 中，GADZ11 对 L-Glu 的催化效率最高（2.19 mM·s）。表达 GADZ11 的工程大肠杆菌菌株被用作全细胞生物催化剂来生产 GABA。重复使用 14 次后，细胞在 14 小时内以平均摩尔转化率 98.6%生产 GABA。
对来自芽孢杆菌菌株的三种重组 GAD 进行了功能鉴定。异源表达 GADZ1、GADZ11 和 GADZ20 的工程大肠杆菌菌株可以在无缓冲液、高 L-Glu 浓度的条件下完成 L-Glu 到 GABA 的生物合成。新型工程大肠杆菌菌株有潜力成为 GABA 工业生产的具有成本效益的生物转化平台。
