谷氨酸脱羧酶和谷氨酸脱氢酶基因的串联表达及其对GABA产量影响  

Effect of gadB and gdh Co-expression on Bacterial γ-aminobutyric Acid Production

作　　者：罗秀针[1] 林燕燕[1] 陈雅静[1] 张文华[1] 谢伟容[1] LUO Xiu-zhen;LIN Yan-yan;CHEN Ya-jing;ZHANG Wen-hua;XIE Wei-rong(Zhangzhou Health Vocational College,Zhangzhou,Fujian 363000,China)

机构地区：[1]漳州卫生职业学院,福建漳州363000

出　　处：《福建农业学报》2018年第7期744-749,共6页Fujian Journal of Agricultural Sciences

基　　金：漳州市自然科学基金项目(ZZ2016J37)

摘　　要：为构建一株无外源L-谷氨酸(L-Glu)条件下可直接转化葡萄糖生产γ-氨基丁酸(GABA)的安全基因工程菌,将植物乳杆菌GABA合成途径的关键酶——谷氨酸脱羧酶基因gadB与L-Glu合成途径中的关键酶谷氨酸脱氢酶基因gdh进行串联表达,导入产谷氨酸菌株谷氨酸棒杆菌SF016中,检测其对L-Glu及GABA产量的影响。经摇瓶发酵40h重组菌SF016-pgg谷氨酸脱羧酶的酶活达0.63mol·min^(-1)·g^(-1),而谷氨酸脱氢酶的酶活达0.131mol·min^(-1)·g^(-1),比原始菌株提高了约2.0倍。重组菌SF016-pgg以葡萄糖为碳源,通过40h发酵罐发酵可积累产生23.12g·L^(-1)的GABA,说明串联表达gadB和gdh基因有效实现重组菌在以葡萄糖为单一碳源、无外源L-Glu存在的培养基中直接发酵生产GABA。该生产方式的成本明显降低,且产品的安全性高,可用于食品、饲料或医药等行业。This study aimed to create a genetically engineered bacterium that could produceγ-aminobutyric acid(GABA)directly from glucose without exogenous L-glutamic acid(L-Glu).The gadB and gdh genes responsible for the generation of two critical enzymes,glutamic acid decarboxylase(GAD)and glutamate dehydrogenase(GDH),respectively,in the synthesis of plant lactobacillus GABA were co-expressed in a Glu-producing strain of Corynebacterium glutamicum,SF016.The resulting effects on GABA production by the recombinational strain,SF016-pgg,were analyzed.The activities of GAD and GDH in SF016-pggnearly doubled after incubation in a shaking flask for 40 h reaching 0.63 mol·min-1·g-1 and 0.131 mol·min-1·g-1,respectively.Furthermore,the SF016-pgg production of GABA from glucose as a single carbon source totaled 23.12 g·L-1 in a 40 h fermentation in a tank.The results seemed to clearly demonstrate the effectiveness of the gadB and gdh co-expressed recombinant strain on producing GABA by converting glucose without exogenous addition of L-Glu.As a result,the GABA production cost was significantly reduced making the industrialization of food,feed and/or pharmaceutical applications exceedingly promising.

关 键 词：谷氨酸脱羧酶 谷氨酸脱氢酶 谷氨酸生产菌SF016 基因串联表达 

分 类 号：Q784[生物学—分子生物学]