Comparative Analysis of the In Vitro Fermentation Characteristics of Polysaccharides from Polygonatum cyrtonema Hua with Different Growth Years Using Human Fecal Microbiota

Polygonatum cyrtonemaHua polysaccharides (PCPs) are bioactive components with antioxidant and immunomodulatory properties. However, whether the polysaccharides derived from elderPolygonatum cyrtonemaexhibit superior health benefits remains unclear. This study systematically compared the in vitro fermentation characteristics, gut microbiota-modulating effects, and short-chain fatty acid (SCFA) production of PCPs extracted from three-year-old (TPP), five-year-old (FPP), and eight-year-old (EPP) plants using a human fecal fermentation model. The fermentation dynamics were evaluated by monitoring pH, OD600, and the consumption of total and reducing sugars, while the structural degradation and compositional differences in PCPs were tracked via molecular weight distribution and monosaccharide composition analysis. The results showed that all three PCPs were degraded and utilized by gut microbiota, accompanied by decreased pH, increased OD600, and enhanced antioxidant activities. High-throughput 16S rDNA sequencing revealed that, at the phylum level, all PCPs increased the Firmicutes/Bacteroidetes ratio. At the genus level, they reduced the abundance of harmful bacteria such asSutterellaand increased beneficial bacteria includingBifidobacteriumandMegasphaera. Furthermore, gas chromatography (GC) analysis demonstrated that, compared with FPP, TPP and EPP significantly promoted the production of SCFAs. In summary, this study indicates that the in vitro fermentation characteristics and prebiotic properties of PCPs vary with growth years, and a comprehensive evaluation suggests that three-year-oldPolygonatum cyrtonemaHua represents a promising raw material for the development of functional foods.