Structure analysis and in vitro evaluation of probiotic properties for polysaccharides from Phellinus baumii extracted with phosphotungstic acid assistance

Heteropolysaccharides were extracted from Phellinus baumii using hot water assisted by phosphotungstic acid, and their physicochemical properties and structures were analyzed. Two isolated components (SPB and SPC) were composed of fucose, galactose, glucose and mannose, with molecule weight of 12.6 kDa and 9.4 kDa, respectively. Structural analysis showed that →6)-Galp-(1→ and →4)-Glcp-(1→ were the main 2D structural fragments in SPB, while →6)-Galp-(1→ and →6)-Glcp-(1→ predominated in SPC. After 48 h of in vitro fermentation with human fecal inoculum, the concentration of propionic acid was extensively boosted (166.3–538.0 μg/mL) by SPB. In addition, the heteropolysaccharides could promote the abundance and diversity of gut microbiota. SPB markedly promoted proliferation of Limosilactobacillus, Megamonas and Bifidobacterium. KEGG-based functional gene prediction implied that biosynthesis of antibiotics, secondary metabolites and ribosome were promoted by SPB component, indicating a stronger probiotic proliferative ability compared to SPA. Overall, these findings emphasized the potential of these heteropolysaccharides possess to maintain the gut health as a potential prebiotic supplemented in foods and nutraceuticals.