重组大肠杆菌全细胞催化合成NMN

NMN Production by Whole-Cell Catalysis of Recombinant Escherichia coli

摘要:

基于前期研究构建的一株能以烟酰胺(nicotinamide，NAM)和葡萄糖为底物高产β-烟酰胺单核苷酸(β-nicotinamide mononucleotide，NMN)的大肠杆菌工程菌株Escherichia coli BL21(DE3)-NF017，采用全细胞催化方式进行NMN合成。首先，在摇瓶水平上对菌株培养过程的发酵培养基类型、诱导温度和诱导剂异丙基-β-D-硫代吡喃半乳糖苷(IPTG)浓度，以及全细胞催化过程的反应体系初始pH、反应温度和底物NAM与葡萄糖的添加比例（质量浓度比）进行了优化，在最优条件下，NMN的生成量（质量浓度）达1.84 g/L。为了进一步提高NMN的生成量，在5 L发酵罐上对全细胞催化过程中溶氧水平和底物NAM的流加方式进行控制和优化。最终，应用恒定速度流加NAM的补料模式，NMN的生成量提高至12.24 g/L，底物NAM的摩尔转化率达85.65%。该研究结果为应用全细胞催化法生产NMN提供了一定参考。

Abstract:

Based on previous research, a genetically engineered strain of Escherichia coli BL21(DE3)-NF017 has been constructed which could synthesize of β-nicotinamide mononucleotide (NMN) using nicotinamide (NAM) and glucose as substrates with high yield. NMN synthesis was carried out in this study using a whole-cell catalytic approach. Initially, optimization was performed at the flask level for fermentation medium type, induction temperature, inducer isopropyl-β-D-thiogalactopyranoside (IPTG) concentration, and the factors of whole-cell catalysis process including the initial pH, reaction temperature, and ratio of substrate NAM to glucose. Under the optimal conditions, the NMN yield reached 1.84 g/L. Subsequently, to further improve NMN production, the control of different dissolved oxygen levels and various substrate NAM feeding strategies were optimized in a 5 L bioreactor. Finally, by a constant speed feeding rate of NAM, the NMN yield was increased to 12.24 g/L, with a molar conversion ratio of 85.65%. The research results could provide references for NMN production by whole-cell catalysis.