Construction and expression of a polycistronic plasmid encoding N-acetylglucosamine 2-epimerase and N-acetylneuraminic acid lyase simultaneously for production of N-acetylneuraminic acid

► Encoding enzymes for two reactions in one plasmid simplified fermentation process. ► Activities of two types of N-acetylglucosamine 2-epimerase were compared. ► Intact E. coli cells avoid adding ATP to activate N-acetylglucosamine 2-epimerase. ► Lowering N-acetylglucosamine 2-epimerase expression level improved its solubility. ► High production of 61.3 g/l N-acetylneuraminic acid.