工程化大肠杆菌的烟酰胺单核苷酸生产及发酵优化

Production and fermentation optimization of nicotinamide mononucleotide by engineered Escherichia coli

烟酰胺单核苷酸(nicotinamide mononucleotide,NMN),是一种生物活性核苷酸,其在改善身体机能、修复运动损伤以及延缓细胞衰老等方面发挥积极作用。本研究以实验室先前保藏的大肠杆菌(Escherichia coli)Z1为出发菌株,经系统的代谢工程改造:削弱竞争途径、弱化产物降解途径以及增加底物葡萄糖的转化,获得一株能够有效生物合成NMN的工程菌株Z5,NMN的产量达到252.2 mg/L。在单因素实验的基础上,通过响应面法设计优化菌株Z5的发酵培养基成分,在最佳条件下的NMN产量为265.4 mg/L,相比出发菌株提高75.1%。随后,对菌株培养条件进行优化,最佳培养条件为pH=7.5,接种量4%,摇床转速150r/min。5L发酵罐的补料分批发酵,菌株Z5的NMN产量在发酵24 h达到4.21 g/L,烟酰胺转化率为48.7%。因此,经过对菌株的代谢工程改造和发酵条件优化,NMN的产量得到有效提升,为规模化生产NMN提供一定的参考价值。

Nicotinamide mononucleotide(NMN)is a biologically active nucleotide,which plays an active role in improving body function,repairing sports injuries and delaying cell aging.In this study,Escherichia coli Z1 previously preserved in the laboratory was taken as the original strain.Through systematic metabolic modification of strain Z1:weakening the competition pathway,weakening the degradation pathway of products and increasing the transformation of substrate glucose,an engineering strain Z5 which could effectively biosynthesize NMN was successfully obtained,and its NMN production was 252.2 mg/L.On the basis of single factor experiment,Box-Behnken method was used to design and optimize the fermentation medium components of strain Z5.Under the optimal conditions,the NMN production was 265.4 mg/L,which was 75.1%higher than that of the original strain.Then,the optimum culture conditions were as follows:pH=7.5,inoculation amount 4%,shaking speed 150 r/min.After fed-batch fermentation in a 5 L fermentor,the strain Z5 produced NMN 4.21 g/L in 24 h,and the nicotinamide conversion rate was 48.7%.Therefore,the production of NMN is effectively improved by metabolic engineering and optimization of fermentation conditions,which provides certain reference value for large-scale production of NMN.