Systematic Metabolic Engineering for Enhanced Cytidine 5′-Monophosphate Production in Escherichia coli

Cytidine 5′-monophosphate (5′-CMP) is a key intermediate in various nucleotide derivatives and is widely used in the food and pharmaceutical industries. In this study, the titer of 5′-CMP in engineered Escherichia coli CM006, which blocks the degradation pathway of 5′-CMP, increased 134.7-fold compared to E. coli MG1655. Integrated expression of the 5′-CMP diphosphate hydrolase gene nudG significantly enhanced the 5′-CMP titer, reduced orotic acid accumulation, and alleviated feedback inhibition in the 5′-CMP synthesis pathway. By blocking cytidine degradation and increasing carbon flux from cytidine to 5′-CMP, the 5′-CMP titer in E. coli CM011 was increased to 338.2 mg/L. Furthermore, by enhancing the supply of the precursor 5-phospho-α-D-ribose 1-diphosphate (PRPP), the 5′-CMP titer in E. coli CM012 reached 417.9 mg/L, the highest value reported to date. The results and methods presented in this study are of great significance for the sustainable industrial production of 5′-CMP.