产γ-氨基丁酸乳酸菌的筛选及诱变育种

Screening and Mutation Breeding of Lactic Acid Bacteria with Enhanced Ability for γ-Aminobutyric Acid Production

利用乳酸菌分离培养基从酸菜汁中分离菌株。经过初筛、复筛后得到的菌株Lp-Lw-131有较好的产γ-氨基丁酸(GABA)能力。对菌株进行形态学鉴定和生理生化实验确定该菌为植物乳杆菌,编号为Lp-Lw-131。利用菌株体内的谷氨酸脱羧酶(GAD)将L-谷氨酸钠脱羧转化成GABA,用比色法测定GABA的产量为0.917g/L。以Lp-Lw-131为出发菌株进行紫外线和硫酸二乙酯(DES)诱变,以致死率为标准确定最佳诱变条件为:紫外照射距离30cm,照射时间90s;DES体积分数为25%醇溶液,处理时间20min,诱变后获得一株突变株Lp-Lw-131-34。连续传代10次后遗传性状稳定,平均GABA产量为1.815g/L,是出发菌株的1.979倍。

Lactic acid bacteria were isolated from pickled Chinese cabbage using BCP medium. After two rounds of screening, strain Lp-Lw-131 having a higher ability to produce γ-amino butyric acid （GABA） was obtained. The strain was identified as Lactobacillus plantarum by morphological observation and physiological and biochemical tests. The yield of GABA generated from the decarboxylation of L-monosodium glutamate catalyzed by glutamate decarboxylase （GAD） from Lp-Lw-131 was determined by colorimetrically to be 0.917 g/L. This strain was irradiated with ultraviolet light and then mutagenized with diethyl sulfate （DES） to improve its ability for GABA production. Based on its lethality, the optimal conditions for mutagenesis in strain Lp-Lw-131 were UV irradiation for 90 s at a distance of 30 cm from the light source followed by treatment with a 25% ethanol solution of DES for 20 min. A mutant strain named Lp-Lw-131-34 was obtained, which maintained its genetic stability after 10 successive passages, providing an average yield of GABA of 1.815 g/L, showing an 1.979-fold increase over the initial strain Lo-Lw-131.