大肠杆菌全细胞转化联产L-2-氨基丁酸和D-葡萄糖酸

Whole-cell biotransformation for simultaneous synthesis of L-2-aminobutyric acid and D-gluconic acid in recombinant Escherichia coli

摘要:

以大肠杆菌BL21(DE3) 为表达宿主，构建两株分别表达L-苏氨酸脱氨酶 (LTD，基因来源大肠杆菌) 和共表达亮氨酸脱氢酶 (LDH，来源蜡样芽孢杆菌)/葡萄糖脱氢酶 (GDH，来源枯草芽孢杆菌) 的重组大肠杆菌，在此基础上，构建了一种以L-苏氨酸和D-葡萄糖为底物联产L-2-氨基丁酸 (L-ABA) 和D-葡萄糖酸的全细胞转化系统。通过转化条件 (温度、pH、细胞通透性和菌体量) 优化，并采用分批补料策略，164 g/L L-苏氨酸和248 g/L D-葡萄糖最终转化得到141.6 g/L的L-ABA和269.4 g/L的D-葡萄糖酸，时空得率分别达到7.1 g/(L?h) 和13.5 g/(L?h)，得率超过99%。本研究使用价格低廉的大宗化学品高效率生产出有较高附加值的产物，全细胞转化系统无需额外添加昂贵的辅酶，更适用于工业化生产。

Abstract:

A whole-cell catalyst using Escherichia coli BL21(DE3) as a host, expressing L- threonine dehydratase from Escherichia coli, and co-expressing leucine dehydrogenase from Bacillus cereus and glucose dehydrogenase from Bacillus subtilis for cofactor regeneration, was constructed and used for one-pot production of L-2-aminobutyric acid (L-ABA) and D- gluconic acid from L-threonine and D-glucose. We used shake-flask culture to study the whole-cell catalytic condition including temperature, pH, proper permeabilization of cells and optimal wet cells amount. Moreover, the whole-cell catalyst was cultured in 5-L fermentor by fed-batch fermentation, and 164 g/L L-threonine and 248 g/L D-glucose were converted to 141.6 g/L L-ABA and 269.4 g/L D-gluconic acid. The whole-cell catalyst is promising to fulfill industrial requirements for L-ABA and D-gluconic acid.