School of Chemical Engineering and Bioengineering, University of Ulsan, Nam-gu, Ulsan, Korea.
Bioprocess Biosyst Eng. 2012 May;35(4):645-50. doi: 10.1007/s00449-011-0634-8. Epub 2011 Oct 5.
Gamma-aminobutyric acid (GABA) is a non-essential amino acid and a precursor of pyrrolidone, a monomer of nylon 4. GABA can be biosynthesized through the decarboxylation of L: -glutamate by glutamate decarboxylase. In this study, the effects of glutamate decarboxylase (gadA, gadB), glutamate/GABA antiporter (gadC) and GABA aminotransferase (gabT) on GABA production were investigated in Escherichia coli. Glutamate decarboxylase was overexpressed alone or with the glutamate/GABA antiporter to enhance GABA synthesis. GABA aminotransferase, which redirects GABA into the TCA cycle, was knock-out mutated. When gadB and gadC were co-overexpressed in the gabT mutant strain, a final GABA concentration of 5.46 g/l was obtained from 10 g/l of monosodium glutamate (MSG), which corresponded to a GABA yield of 89.5%.
γ-氨基丁酸（GABA）是非必需氨基酸，也是吡咯烷酮的前体，吡咯烷酮是尼龙 4 的单体。GABA 可以通过谷氨酸脱羧酶对 L：-谷氨酸的脱羧作用生物合成。在本研究中，研究了谷氨酸脱羧酶（gadA、gadB）、谷氨酸/ GABA 反向转运体（gadC）和 GABA 转氨酶（gabT）对大肠杆菌中 GABA 生产的影响。单独或与谷氨酸/ GABA 反向转运体一起过表达谷氨酸脱羧酶以增强 GABA 合成。GABA 转氨酶将 GABA 重定向到 TCA 循环，被敲除突变。当 gadB 和 gadC 在 gabT 突变株中共表达时，从 10 g/L 的味精中获得了 5.46 g/L 的最终 GABA 浓度，对应的 GABA 得率为 89.5%。
