• 中文核心期刊
  • CSCD来源期刊
  • 中国科技核心期刊
  • CA、CABI、ZR收录期刊

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

  • 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40 h重组菌SF016-pgg谷氨酸脱羧酶的酶活达0.63 mol·min-1·g-1,而谷氨酸脱氢酶的酶活达0.131 mol·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40 h发酵罐发酵可积累产生23.12 g·L-1的GABA,说明串联表达gadBgdh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。

     

    Abstract: This study aimed to create a genetically engineered bacterium that could produce γ-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.

     

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