代谢工程改造大肠杆菌生产辅酶Q10

Production of coenzyme Q10 by metabolically engineered Escherichia coli

摘要:

辅酶Q10 (CoQ10) 是一种脂溶性抗氧化剂，具有提高人体免疫力、延缓衰老和增强人体活力等功能，广泛应用于制药行业和化妆品行业。微生物发酵法能可持续性生产辅酶Q10，具有越来越多的商业价值。本研究首先将来自类球红细菌的十聚异戊二烯焦磷酸合成酶基因 (dps) 整合到大肠杆菌ATCC 8739染色体上，敲除内源的八聚异戊二烯焦磷酸合成酶基因 (ispB)，使内源的辅酶Q8合成途径被辅酶Q10合成途径取代，得到稳定生产辅酶Q10的菌株GD-14，其辅酶Q10产量达0.68 mg/L，单位细胞含量达0.54 mg/g DCW。随后用多个固定强度调控元件在染色体上对MEP途径的关键基因dxs和idi基因以及ubiCA基因进行组合调控，将辅酶Q10单位细胞含量提高2.46倍 (从0.54到1.87 mg/g)。进一步引入运动发酵单胞菌Zymomonas mobilis的Glf转运蛋白代替自身的磷酸烯醇式丙酮酸：碳水化合物磷酸转移酶系统 (PTS)，使辅酶Q10产量进一步提高16%。最后，对高产菌株GD-51进行分批补料发酵，辅酶Q10产量达433 mg/L，单位细胞含量达11.7 mg/g DCW。这是目前为止文献报道的大肠杆菌产辅酶Q10最高菌株。

关键词:辅酶Q10，同源重组，基因表达调控，大肠杆菌

Abstract:

Coenzyme Q10 (CoQ10) is a lipophilic antioxidant that improves human immunity, delays senility and enhances the vitality of the human body and has wide applications in pharmaceutical and cosmetic industries. Microbial fermentation is a sustainable way to produce CoQ10, and attracts increased interest. In this work, the native CoQ8 synthetic pathway of Escherichia coli was replaced by the CoQ10 synthetic pathway through integrating decaprenyl diphosphate synthase gene (dps) from Rhodobacter sphaeroides into chromosome of E. coli ATCC 8739, followed by deletion of the native octaprenyl diphosphate synthase gene (ispB). The resulting strain GD-14 produced 0.68 mg/L CoQ10 with a yield of 0.54 mg/g DCW. Modulation of dxs and idi genes of the MEP pathway and ubiCA genes in combination led to 2.46-fold increase of CoQ10 production (from 0.54 to 1.87 mg/g DCW). Recruiting glucose facilitator protein of Zymomonas mobilis to replace the native phosphoenolpyruvate: carbohydrate phosphotransferase systems (PTS) further led to a 16% increase of CoQ10 yield. Finally, fed-batch fermentation of the best strain GD-51 was performed, which produced 433 mg/L CoQ10 with a yield of 11.7 mg/g DCW. To the best of our knowledge, this was the highest CoQ10 titer and yield obtained for engineered E. coli.

Key words:CoQ10, homologus recombination, modulation of gene expression, Escherichia coli