过量表达琥珀酸输出蛋白SucE对谷氨酸棒杆菌厌氧生产琥珀酸的影响

Effect of Overexpression of Succinate Exporter Suc E on Anaerobic Succinate Production by Corynebacterium glutamicum

谷氨酸棒杆菌Corynebacterium glutamicum ATCC 13032在厌氧条件下通过三羧酸循环还原臂合成琥珀酸。高效地将细胞内的琥珀酸输出到胞外,对琥珀酸的生物合成具有重要意义。本实验以C.glutamicum XZ为出发菌株过表达琥珀酸输出蛋白表达基因suc E。突变株C.glutamicum XZ(p Exhsuc E)的琥珀酸得率提高了7%,生产率提高了19%。通量分析表明,过表达suc E基因后乙醛酸循环的相对通量提高了50%。采用两阶段培养,突变株C.glutamicum XZ(p Exhsuc E)的琥珀酸产量达到518 mmol·L-1,厌氧阶段的比生产率为0.95 mmol g CDW-1·h-1,1 mol glucose的平均得率为1.5 mol。

Corynebacterium glutamicum ATCC 13032 produces succinate through the reductive tricarboxylic acid cycle under anaerobic conditions. Efficient export of succinate into the culture supernatant is important to increase its production. In this study,suc E gene overexpression was introduced into strain C.glutamicum XZ. The resulting strain C. glutamicum XZ（ p Exhsuc E） showed a 7% increase in succinate yield and a 19% increase in succinate productivity. Also,the relative flux of the glyoxylate pathway increased by 50%. Using two-stage culture,succinate titer up to 518 mmol·L- 1was achieved with a specific productivity of 0. 95 mmol g CDW- 1·h- 1and a yield of 1. 5 mol（ mol glucose）- 1.