In vitro digestion stability of a Bifidobacterium-derived extracellular polysaccharides and its prebiotic potential in gut microbiota modulation.

This study systematically evaluated the digestive stability and prebiotic potential of extracellular polysaccharides (EPS) derived from Bifidobacterium animalis RH using in vitro digestion and fecal fermentation models. Digestion (INFOGEST 2.0) revealed that EPS maintained structural integrity: total carbohydrates remained stable (59.38-60.12 %), while reducing sugars increased moderately (0.125-0.207 mg/mL), indicating partial dissociation. Structural characterization (SEM, GPC, IC, FT-IR) confirmed preserved molecular weight, monosaccharide composition, and functional groups, alongside retained α-glucosidase and enhanced α-amylase inhibition. Fermentation with human fecal microbiota revealed digested EPS selectively enriched beneficial genera (Bacteroides, Bifidobacterium, Collinsella, Parabacteroides, and Faecalibacterium) while suppressing pathogens (Escherichia-Shigella, Fusobacterium, Lachnospiraceae_UCG-010, Phascolarctobacterium, and Dialister). This shift correlated with decreased pH and sustained short-chain fatty acid (SCFA) production (37.63 mmol/L total SCFAs at 24 h), particularly butyrate linked to Faecalibacterium. These findings highlight EPS as a digestion-resistant polysaccharide with significant prebiotic potential as a gut-targeted functional ingredient for supporting intestinal health.