Metabolic engineering of Escherichia coli for uridine-5'-diphosphate N-acetylglucosamine production through salvage...

Uridine-5'-diphosphate N-acetylglucosamine (UDP-GlcNAc) has unique biological activities and is a key precursor for production of glycosaminoglycans and human milk oligosaccharides. Metabolic synthesis is considered as an economic strategy for UDP-GlcNAc production, however, the low titer still cannot meet the production demand. In this study, the salvage pathway was selected and optimized for UDP-GlcNAc production using GlcNAc as the sole carbon source. In addition, five metabolic sites, derived from the uridine synthesis pathway, ATP synthesis pathway, GlcNAc utilization pathway, and the UDP-GlcNAc downstream metabolic pathway, were verified. Ultimately, the strain NGP7-1, which demonstrated the highest UDP-GlcNAc titer of 230.72 mg/L, was obtained through a combination of these optimization sites. Furthermore, after optimizing the addition amount of GlcNAc, the titer of UDP-GlcNAc reached 319.23 mg/L, which was the highest titer obtained by single strains. This study proved the advantages of the salvage pathway and provided an efficient strain for UDP-GlcNAc production, which could be a reference for synthesis of other GlcNAc-based sugars.