Abstract:To investigate the biosynthesis pathway of exopolysaccharides (EPS) in Bifidobacterium longum A17, the authors relied on the whole-genome sequencing, and EPS synthesis-related genes were annotated and subjected to homology analysis using eggNOG-mapper, KEGG, GO data annotation, and local sequence alignments. According to the homology analysis, an A17 eps gene cluster consisting of 19 genes with a length of approximately 20 kb was obtained. The synthesis pathway of the precursor glyconucleotides of EPS was predicted, and the key gene pgm involved in the pathway was found and heterologously expressed. The eps gene cluster is responsible for the synthesis of eps monomer repeat units and the subsequent EPS synthesis process related to the export. In the EPS precursor glyconucleotide synthesis pathway, Bifidobacterium longum A17 utilizes glucose and lactose to form 2 precursor glyconucleotides, UDP-Gal and UDP-Glc. Among them, pgm encodes 1→6 glucose phosphomutase, whose production and activity are enzyme related to EPS synthesis.
