Prebiotic effects and functional insights into gut microbiota mediated by Qingke β-glucan of different molecular weights in vitro fermentation

Qingke β-glucan (QBG), a gastrointestinal indigestible grain polysaccharide, is used as prebiotic and delivery carrier to mediate gut microbiota, while the mechanism of QBG of different MWs degraded by the gut microbiota remain uncertain. In this study, we investigated the impacts of QBG with different MWs on gut microbiota, SCFAs, and the degrading degree of polysaccharides in vitro fermentation. QBG groups significantly increased the total SCFAs, which is consistent with the results predicted by PICRUSt2 based on the KEGG pathway. The 27 functional genes associated with SCFAs metabolism were identified. Acetate and propionate synthesis was primarily mediated by the pta, ackA , and ACSS genes, whereas butyrate production mediated by the ptb, buk , and atoA genes. The low-MW QBG produced more SCFAs than the high-MW QBG after fermentation, suggesting that polysaccharide MW influences its biological functionality. These findings support polysaccharide-based gut microbiota-targeting drug and food development.