Biochemical analysis of cross-feeding behaviour between two common gut commensals when cultivated on plant-derived arabinogalactan

In this paper, we reveal and characterize cross-feeding behaviour between the common gut commensal Bacteroides cellulosilyticus (Baccell) and certain bifidobacterial strains, including Bifidobacterium breve UCC2003, when grown on a medium containing Larch Wood Arabinogalactan (LW-AG). We furthermore show that cross-feeding is dependent on the release of β-1,3-galacto-di/trisaccharides (β-1,3-GOS), and identified that the bga gene cluster of B. breve UCC2003 allows β-1,3-GOS metabolism. The product of bgaB is presumed to be responsible for the import of β-1,3-GOS, while the bgaA gene product, a glycoside hydrolase family 2 member, was shown to hydrolyse both β-1,3-galactobiose and β-1,3-galactotriose into galactose monomers. This study advances our understanding of strain-specific syntrophic interactions between two glycan degraders in the human gut in the presence of AG-type dietary polysaccharides.