Optimization of γ-Aminobutyric Acid Liquid Fermentation Conditions and its Fed-Batch Fermentation

In order to enhance the γ-aminobutyric acid (GABA) production,the effects of operation conditions (aeration and pH) on GABA batch fermentation by Lactobacillus brevis CGMCC NO.1306 in a 3.7 L stirred fermenter were investigated. The results show that the aeration and pH have significant effects on GABA production. The aerobic cultivation is advantageous to obtain high yield of dry cell weight (2.78 g·L-1),but the anaerobic cultivation is advantageous to GABA accumulation,and its GABA yield reaches 23.94 g·L-1 at 72 h. In order to assess the effects of pH on GABA production,three batch processes with different pH controlled at 4.5,5.0 and 5.5,respectively,were conducted. It was found that the highest GABA yield of 40.73 g·L-1 can be obtained at 72 h with pH controlled at 5.0. The fed-batch fermentation of GABA was studied preliminarily; it was found that,after four times L-sodium glutamate (L-MSG) addition,the yield of GABA reaches 76.36 g·L-1 at 108 h,and this GABA yield which is enhanced significantly by fed-batch fermentation is 128.6%,219% and 87.5%,respectively,higher than that of shake flask fermentation,anaerobic fermentation and fermentation with pH controlled at 5.0.