Isolation, structural characterization and multiple activity of a novel exopolysaccharide produced by Gelidibacter...

Microbial exopolysaccharides have been extensively explored due to their distinctive structural features and physiological activities, making them suitable for diverse applications in the food and environmental applications. Current studies mainly focus on the structural and functional characterization of exopolysaccharides from known strains, with limited exploration of novel strains. In this study, a novel exopolysaccharide was produced by Gelidibacter sp. PG-2 with a yield of 874 mg·L^-1. The purified exopolysaccharides, termed as ZPS, had a molecular weight of 45,514 Da and contained numerous hydroxyl and carbonyl groups. ZPS was a heteropolysaccharide composed of mannose, glucosamine, glucuronic acid, galactonic acid, galactosamine, glucose, galactose, and fucose, with a molar ratio of 54.98: 4.05: 6.69: 1.00: 1.46: 2.95: 2.92: 1.55. ZPS linkage comprised Glcp-(1→, Manp-(1→, →2)-Manp-(1→, →4)-Galp-(1→, and →4)-Manp-(1→. The morphology of ZPS presented the smooth surface, spherical nanoparticle, and irregular network structure. ZPS demonstrated thermal stability and emulsification activity. ZPS potently stimulated macrophage phagocytic function and effectively inhibited the migration of cancer cells, thereby enhancing overall immunomodulatory activity. Additionally, ZPS featured cryoprotective activity and flocculation property. Overall, the multiple activity of ZPS hold tremendous potential in the food and pharmaceutical industries, offering new dimensions for novel microbial exopolysaccharides.