代谢工程改造大肠杆菌生产L-丝氨酸

Production of L-serine by metabolically engineered Escherichia coli

L-丝氨酸是一种具有重要生理学功能的中性氨基酸,广泛应用在食品、化妆品和医药等领域。为构建L-丝氨酸的生产菌株,对Escherichia coli MG1655进行了系统的代谢工程改造。采用的方法策略包括减弱L-丝氨酸的降解,增强L-丝氨酸合成酶类的表达以及转运系统的改造。特别是利用启动子P trp调控丝氨酸羟甲基转移酶的表达,减弱了L-丝氨酸向甘氨酸的降解途径,显著增强了L-丝氨酸的合成。最终所得菌株SER09摇瓶发酵24 h,L-丝氨酸产量可达13.53 g/L;在5 L发酵罐上发酵28 h,L-丝氨酸产量达到22.31 g/L。该研究从头构建了1株产L-丝氨酸的平台菌株,具有较好的应用前景。

L-Serine is a neutral amino acid with important physiological functions widely used in food,cosmetics,and medicine industries.Escherichia coli MG1655 was systematically modified by reducing the degradation of L-serine and enhancing the expression synthetases and trans-system to produce L-serine.In particular,P trp was used to regulate the expression of serine hydroxymethyl transferase to decrease the degradation pathway of L-serine to glycine.The synthesis of L-serine significantly enhanced.The obtained strain SER09 produced 13.53 g/L of L-serine by shake-flask fermentation after 24 hand 22.31 g/L L-serine in a 5 L fermenter for 28 h.A platform strain producing L-serine was constructed,which has a good application prospect.