重组谷氨酸脱羧酶大肠杆菌合成γ-氨基丁酸条件的优化

Optimization of Conversion Conditions for Biosynthesizing γ-Aminobutyric Acid by Recombinant Glutamate Decarboxylase from Escherichia coli

研究重组谷氨酸脱羧酶大肠杆菌合成γ-氨基丁酸(γ-aminobutyric acid,GABA)的适宜条件。检测温度、p H值、表面活性剂、金属离子、底物与菌体质量比以及反应体系体积对GABA转化效率的影响。结果表明:最优转化条件为:转化体系5 m L、底物L-谷氨酸钠浓度0.1 mol/L、重组大肠杆菌细胞6.4 mg(干质量)、Triton-100体积分数0.06%、Ca2+浓度0.6 mmol/L,转化温度45℃、反应体系p H 4.5。在该体系下反应7 h,GABA合成量达到26.1 g/L,GABA转化效率在1 h时达到最高,为13.8 g/(g h),较优化前提高1.5 倍。

The conditions for the synthesis of γ-aminobutyric acid(GABA) using glutamate decarboxylase from recombinantE. coli cells were optimized in this work. The effects of temperature, p H, surfactants, metal ions, the ratio of substrate and cells and the transformation system volume on the productivity of GABA were studied. Results indicated that the optimal reaction system volume was 5 m L containing 0.1 mol/L sodium glutamate as the substrate, 6.4 mg of E. coli cells(dry weight), 0.06% Triton-100(volume fraction) and 0.6 mmol/L Ca2+ at p H 4.5. The reaction was allowed to proceed for 7 h at 45 ℃. Under these optimal conditions, the yield of GABA was 26.1 g/L. The transformation efficiency of GABA reached the highest level of 13.8 g/(g·h) after 1 h reaction, which is 2.5 times higher than that observed before optimization.