Abstract:Exopolysaccharides (EPSs) are macromolecules with different sugar residues and are widely used in medicine, food, environment, and other fields. In this study, six components (EPS-1A, EPS-1B, EPS-2, EPS-3, EPS-4, and EPS-5) of the exopolysaccharides produced by Lactiplantibacillus plantarum NM18 were purified using ethanol precipitation, anion exchange method, and gel filtration chromatography, and their primary structures were identified. Components EPS-1A, EPS-1B, and EPS-2 comprised mannose, glucose, and galactose. Component EPS-3 comprised mannose, glucose, galactose, rhamnose, trehalose, and N-acetyl-D-glucosamine. Component EPS-4 comprised mannose, glucose, galactose, and N-Acetyl-D-glucosamine. Component EPS-5 comprised mannose, galactose, and N-acetyl-D-glucosamine, and contained trace amounts of fucose and allose. The methylation reaction of EPS-1A, EPS-1B, and EPS-2 combined with GC-MS analysis showed that EPS-1A and EPS-1B carbohydrate chains mainly comprised →3)-D-Glcp-(1→,→6)-D-Galp-(1→,→4)-D-Glcp-(1→ and →6)-D-Manp-(1→, with the terminus being Glcp-(1→. The EPS-2 carbohydrate chains mainly comprised →6)-D-Galp-(1→ and →6)-D-Manp-(1→, with the terminus being D-Glcp-(1→. Components EPS-1A, EPS-1B, and EPS-2 have a mixture of α and β type glycosidic bonds. In conclusion, this study provides theoretical basis for further study and application of the biological activity of exopolysaccharides produced by strain NM18
