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.
