Large-scale production of CMP-NeuAc and sialylated oligosaccharides through bacterial coupling

Abstract

A large-scale production system of cytidine 5′-monophospho-N-acetylneuraminic acid (CMP-NeuAc) and sialyloligosaccharides was established by a whole-cell reaction through the combination of recombinant Escherichia coli strains and Corynebacterium ammoniagenes. For the production of CMP-NeuAc, two recombinant E. coli strains were generated that overexpressed the genes of CMP-NeuAc synthetase and CTP synthetase, respectively. C. ammoniagenes contributed to the formation of UTP from orotic acid. CMP-NeuAc was accumulated at 27 mM (17 g/l) after a 27-h reaction starting with orotic acid and N-acetylneuraminic acid. When E. coli cells that overexpressed the α-(2 → 3)-sialyltransferase gene of Neisseria gonorrhoeae were put into the CMP-NeuAc production system, 3′-sialyllactose was accumulated at 52 mM (33 g/l) after an 11-h reaction starting with orotic acid, N-acetylneuraminic acid, and lactose. Almost no oligosaccharide byproducts other than 3′-sialyllactose were observed after the reaction. The production of 3′-sialyllactose at a 5-l jar fermenter scale was almost the same as that at a beaker scale, which indicated the high potential of the 3′-sialyllactose production on an industrial scale.