We investigated the effect of cell-surface display of glutamate decarboxylase (GadB) on gamma-aminobutyric acid (GABA) production in recombinant Escherichia coli. We integrated GadB from the hyperthermophilic, anaerobic archaeon Pyrococcus horikoshii to the C-terminus of the E. coli outer membrane protein C (OmpC). After 12 hr of culturing GadB-displaying cells, the GABA concentration in the extracellular medium increased to 3.2 g/l, which is eight times that obtained with cells expressing GadB in the cytosol. To further enhance GABA production, we increased the temperatures of the culture. At 60°C, the obtained GABA concentration was 4.62 g/l after 12 hr of culture, and 5.35 g/l after 24 hr, which corresponds to a yield of 87.7%.

中文翻译：

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大肠杆菌中堀越热球菌谷氨酸脱羧酶的全细胞展示用于高滴度细胞外γ-氨基丁酸生产

我们调查了谷氨酸脱羧酶 (GadB) 的细胞表面展示对重组大肠杆菌中 γ-氨基丁酸 (GABA) 生产的影响。我们将来自超嗜热厌氧古生菌 Pyrococcus horikoshii 的 GadB 整合到大肠杆菌外膜蛋白 C (OmpC) 的 C 端。在培养显示 GadB 的细胞 12 小时后，细胞外培养基中的 GABA 浓度增加到 3.2 g/l，是在胞质溶胶中表达 GadB 的细胞的八倍。为了进一步提高 GABA 产量，我们提高了培养温度。在 60°C 下，培养 12 小时后获得的 GABA 浓度为 4.62 g/l，培养 24 小时后为 5.35 g/l，对应的产率为 87.7%。