[S9-5] Molecular insight into infant gut microbiota formation: Milk oligosaccharides and bifidobacteria
Lactation is a common feeding strategy of eutherian mammals, but at least for humans, its functions go beyond feeding the neonates. Ever since Tissier isolated bifidobacteria from the stool of breast-fed infants, human milk has been postulated to contain compounds that selectively stimulate the growth of bifidobacteria in intestines. However, until relatively recently, there have been no reports to link human milk compound(s) with bifidobacterial physiology. Over the past decade, successive studies have demonstrated that infant gut-associated bifidobacteria are equipped with genetic and enzymatic toolsets dedicated to assimilation of host-derived glycans, especially human milk oligosaccharides (HMOs). Among gut microbes, the presence of enzymes required for degrading HMOs is essentially limited to infant gut-associated bifidobacteria. In this talk, I will summarize the roles of bifidobacterial enzymes in the assimilation of HMOs and show recent studies demonstrating how these enzymes are associated with bifidobacteria-rich microbiota formation in the breast-fed infant guts. Our findings strongly suggest symbiosis and co-evolution between bifidobacteria and humans.