Structure characterization, simulated digestion, and microbial modulation of Pleurotus ostreatus polysaccharides

Edible mushrooms polysaccharides are widely recognized for their biological activities, yet the prebiotic potential of Pleurotus ostreatus polysaccharides (POP) remains underexplored. In this study, POP was isolated, structurally characterized, and evaluated for digestibility and impact on gut microbiota. Structural analysis revealed that POP comprises →4)-α-Glcp-(1→, →3)-β-Glcp-(1→, →4,6)-α-Glcp-(1→ and →3,4)-α-Glcp-(1→ linkages as the backbone, with side chains of 1,6-α-Galp and α-Manp residues. POP was resistant to simulated gastrointestinal digestion. During fecal fermentation, POP significantly increased microbial diversity, with Chao1 and Shannon indices rising by 26.95 % and 32.67 %. Furthermore, POP promoted the relative abundance of beneficial genera like Prevotella (8.1-fold increase), Bacteroides (3.8-fold), and Faecalibacterium (4.4-fold), while reducing opportunistic pathogens including Fusobacterium and Escherichia. Total short-chain fatty acid (SCFA) production reached 54.7 mM at 24 h, particularly acetate, propionate, and butyrate. These results highlight the prebiotic potential of POP and support its application as a functional food ingredient for improving gut health.