Systematic engineering for efficient production of nicotinamide mononucleotide from d-xylose and nicotinamide in Escherichia coli
Chang Su, Lin Cheng, Jin‐Song Gong, Heng Li, Zhenghong Xu, Jin‐Song Shi
Abstract
β-Nicotinamide mononucleotide (NMN) is a direct precursor of the important coenzyme NAD + in the human body and has broad application prospects in healthcare. This study engineered an Escherichia coli BL21 (DE3) strain to efficiently biosynthesize NMN from nicotinamide (NAM) and xylose . Firstly, the nicotinamide phosphoribosyltransferase (Nampt) from Chitinophaga pinensis was selected and heterologous expressed to construct the NAD + remediation pathway for NMN synthesis from nicotinamide (NAM) and in vivo precursor phosphoribosyl pyrophosphate (PRPP). Then, the supply of PRPP was enhanced by constructing the metabolic flux from d -xylose. To facilitate NMN accumulation, the branch pathways, including PRPP competitive pathway, carbon flow competitive pathway, and NMN downstream metabolic decomposition pathway were fine-tuned using CRISPR/Cas9 editing tools. Combined with process optimization of whole-cell biocatalytic reaction, a NMN titre of 497.5 mg·L −1 was obtained. Finally, the scale-up culture was carried out on a 5 L fermenter , and the yield reached 760.2 mg·L −1 . This work achieved green biosynthesis of NMN using xylose as substrate and enhanced the productivity by systematic engineering strategies, presenting more possibilities for the synthesis of NMN from a wide range of monosaccharides .