[W4-1] Roles of the cell surface architecture of Bifidobacterium in the gut colonization
A large number of bacteria reside within the human gastrointestinal (GI) tract. Co-associations among microbes in the GI environment to create a complex, stable, and specific microbiota. The genus Bifidobacterium comprises bacteria that can be found as components of the human gut microbiota. Bifidobacterial cell surface architectures, such as fimbriae, glycosidase, and extracellular vesicle (EV), are involved in the initial physical contact with the host mucosal surface. The anaerobic culture system (“KUHIMM”, Takagi et al., 2016) is a jar fermenter that simulates the human colonic microbiota. We discovered that Bifidobacterium longum cultured in the KUHIMM broth produces abundant EVs. The EVs were collected from B. longum suspension, while the protein composition of EVs was determined using the combination method of proteomics and BIAcore analyses. Importantly, the EVs primarily consisted of cytoplasmic proteins, including several mucin-binding proteins, such as GroEL and transaldolase. These results indicate that symbiotic bacterial metabolites stimulate B. longum EV production. The resulting EVs export several mucin-binding proteins, which may facilitate bifidobacterial colonization.