布氏乳杆菌产γ-氨基丁酸发酵条件的优化

Optimization of Fermentation Conditions for γ-Aminobutyric Acid Production by Lactobacillus buchneri

从中国传统发酵蔬菜中分离获得2株高产γ-氨基丁酸的布氏乳杆菌S37和布氏乳杆菌J68,为进一步提高其产γ-氨基丁酸的能力,对菌株的发酵条件进行优化。结果表明,2株菌产γ-氨基丁酸的最优条件为:发酵时间72 h、发酵温度35℃、底物L-谷氨酸钠浓度400 mmol/L、初始pH 5.0。在此条件下,菌株的γ-氨基丁酸产量分别为233.9 mmol/L和159.3 mmol/L,对应的L-谷氨酸钠转化率分别为58.5%和39.8%。单因素试验发现叶酸、L-半胱氨酸和氯化锰的添加能显著提高菌株的γ-氨基丁酸产量,在此基础上进一步通过响应面试验对其进行优化,发现对于菌株S37最优添加水平分别为8.37 mg/L、0.94 g/L和0.60 g/L,对于菌株J68其最优添加水平分别为10.16 mg/L、0.97 g/L和0.60 g/L。在该最优条件下,2株菌的γ-氨基丁酸产量分别达到312.6 mmol/L和251.2 mmol/L,对应的L-谷氨酸钠转化率分别为78.2%和62.8%。

Two Lactobacillus buchneri strains,S37 and J68,with great ability to produceγ-aminobutyric acid(GABA)had been isolated from Chinese traditional fermentable vegetables in our previous study.In this study,in order to further improve their GABA production ability,the fermentation conditions were optimized.The results showed that the optimal fermentation conditions for the two strains were as follows:time of 72 h,temperature of 35℃,L-monosodium glutamate(L-MSG)concentration of 400 mmol/L,and initial pH of 5.0.Under these conditions,the GABA yields for the two strains were 233.9 and 159.3 mmol/L,respectively,and the L-MSG conversion rates were 58.5%and 39.8%,respectively.The one-factor-at-a-time experiments demonstrated that folic acid,L-cysteine and manganese chloride significantly enhanced the GABA production of the two strains.The addition levels of these compounds were optimized to be 8.37 mg/L,0.94 g/L and 0.60 g/L for strain S37,and 10.16 mg/L,0.97 g/L and 0.60 g/L for strain J68,respectively by response surface methodology,resulting in GABA yields of 312.6 and 251.2 mmol/L and L-MSG conversion rates of 78.2%and 62.8%,respectively.