Sharing of human milk oligosaccharides degradants within bifidobacterial communities in faecal cultures supplemented with Bifidobacterium bifidum

Abstract

Gut microbiota of breast-fed infants are generally rich in bifidobacteria. Recent studies show that infant gut-associated bifidobacteria can assimilate human milk oligosaccharides (HMOs) specifically among the gut microbes. Nonetheless, little is known about how bifidobacterial-rich communities are shaped in the gut. Interestingly, HMOs assimilation ability is not related to the dominance of each species. Bifidobacterium longum susbp. longum and Bifidobacterium breve are commonly found as the dominant species in infant stools; however, they show limited HMOs assimilation ability in vitro. In contrast, avid in vitro HMOs consumers, Bifidobacterium bifidum and Bifidobacterium longum subsp. infantis, are less abundant in infant stools. In this study, we observed altruistic behaviour by B. bifidum when incubated in HMOs-containing faecal cultures. Four B. bifidum strains, all of which contained complete sets of HMO-degrading genes, commonly left HMOs degradants unconsumed during in vitro growth. These strains stimulated the growth of other Bifidobacterium species when added to faecal cultures supplemented with HMOs, thereby increasing the prevalence of bifidobacteria in faecal communities. Enhanced HMOs consumption by B. bifidum-supplemented cultures was also observed. We also determined the complete genome sequences of B. bifidum strains JCM7004 and TMC3115. Our results suggest B. bifidum-mediated cross-feeding of HMOs degradants within bifidobacterial communities.

Minority species influences microbiota formation: the role of Bifidobacterium with extracellular glycosidases in bifidus flora formation in breastfed infant guts

“…This increase was strongly promoted in the cultured sample from an infant born through Caesarean section, in which the bifidus flora was not initially confirmed (Table , Infant C). We found that promoting the growth of preexisting Bifidobacterium was difficult when only HMOs were added, but the addition of B. bifidum stimulated the formation of the bifidus flora (Gotoh et al ., ).…”

“…Keystone species may not always be the controlling agent at all times, but rather only under certain conditions. In the examples that we raised, the presence of an exclusive carbon source like HMOs allowed B. bifidum and LnbX + − B. longum to act as a keystone species in the bifidus flora (Yamada et al ., ; Gotoh et al ., ).…”

“…This suggested that B. bifidum leaves the degraded mono-and oligosaccharides in the medium without using them immediately. When B. longum 105-A strain, which assimilates only LNT, was co-cultured with B. bifidum in the presence of HMOs, its growth was remarkably promoted (Gotoh et al, 2018). Stool samples collected from infants, children and adults were cultured in the presence or absence of each of the four strains of B. bifidum in the medium containing glucose (Glc) or HMOs.…”

When Cultures Meet: The Landscape of “Social” Interactions between the Host and Its Indigenous Microbes

“…[5,[22][23][24] Likewise, in adults, Firmicutes and Bacteroidetes are prominent in the gut, and metabolize dietary plant polysaccharides, which are otherwise indigestible by the mammalian host. Indeed, a mammalian host is unable to complete digestion of the entirety of food or to de novo produce all food-related vitamins that are critically important for a healthy living.…”

Health benefits conferred by the human gut microbiota during infancy

“…In contrast, other bacteria can access and metabolize only specific elements of the HMO mixture. Nevertheless, microbial communities may be capable to act in concert, consecutively breakdown and metabolize HMO structures in a team effort through cross-feeding activities (Egan et al, 2014a,b;Gotoh et al, 2018).…”