Foxtail millet bran dietary fibres foster in vitro beneficial gut microbes and metabolites while suppressing pathobionts

Foxtail millet bran soluble dietary fibre (MBSDF) is a dietary compound with various bioactivities, potentially modulated by the gut microbiota. To elucidate this bioregulatory mechanism, this study focused on the structureal composition and in vitro fermentation characteristics of MBSDF. The results revealed that MBSDF has a molecular weight of 18.26 kDa. The main chain is connected through a glycosidic bond in the form of →4)-α-D-Glcp-(1 → 4)-β-D-Xylp-(1→, being branched by →4, 6)-α-D-Glcp-(1 → O-6 and →3, 4)-β-D-Xylp-(1 → O3 bonds. After 24 h fermentation, the carbohydrate utilisation rate reached 59.15 %, with a decreased molecular weight and monosaccharide composition molar mass ratio. Meanwhile, a increase was observed in the short-chain fatty acid, accompanied by an increased relative abundance of Faecalibacterium, Bifidobacterium and Lactobacillus and suppressed growth of pathogenic Enterococcus. Interestingly, the modulation of gut homeostasis probably occurs via butyrate metabolism pathway. Collectively, MBSDF can selectively regulate the gut microbiota and their metabolites. [Display omitted] •Millet bran soluble dietary fibre selectively modulates the composition of gut microbiota.•Purified fraction can downregulate pH value and promote SCFAs production.•The regulation of intestinal homeostasis primarily occurs through the butyrate metabolic pathway.•Millet bran soluble dietary fibre fractions possess prebiotic potential.