Yao Lili, Lyu Changjiang, Wang Yuting, Hu Sheng, Zhao Weirui, Cao Hongwei, Huang Jun, Mei Lehe
College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China.
Eng Microbiol. 2023 Feb 3;3(2):100077. doi: 10.1016/j.engmic.2023.100077. eCollection 2023 Jun.
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, of and of were inserted into the designed double promoter (P and P ) expression system. Then, Lemo21(DE3) was chosen as the host to minimize the toxic effects of GadC 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 Lemo21(DE3) cells were concentrated to an OD of 20 and reused for three cycles in a 3 M -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 .
细菌中功能性因子γ-氨基丁酸（GABA）的生物合成涉及两种关键蛋白质，一种是细胞内谷氨酸脱羧酶（GadB），另一种是膜结合反向转运蛋白（GadC）。高效共表达合适的GadB和GadC候选蛋白对于提高GABA产量至关重要。在本研究中，将[具体内容1]的[具体内容2]和[具体内容3]的[具体内容4]插入到设计的双启动子（P[具体编号1]和P[具体编号2]）表达系统中。然后，选择Lemo21(DE3)作为宿主以最小化GadC过表达的毒性作用。此外，开发了一种以休眠的工程化Lemo21(DE3)细胞作为生物催化剂的绿色高效GABA合成系统。当工程化的Lemo21(DE3)细胞浓缩至OD为20并在37°C的3M谷氨酸溶液中重复使用三个循环时，总GABA产量在13小时内达到829.08 g/L，转化率为98.7%，这代表了有史以来报道的最高GABA生产率。总体而言，将GadB和GadC的活性pH范围扩展至生理pH，并采用可调节表达宿主来生产膜结合的GadC，是在[具体内容5]中进行高水平GABA生物合成的一种有前景的策略。
