Linking human milk oligosaccharide metabolism and early life gut microbiota: bifidobacteria and beyond

Abstract

SUMMARY Human milk oligosaccharides (HMOs) are complex, multi-functional glycans present in human breast milk. They represent an intricate mix of heterogeneous structures which reach the infant intestine in an intact form as they resist gastrointestinal digestion. Therefore, they confer a multitude of benefits, directly and/or indirectly, to the developing neonate. Certain bifidobacterial species, being among the earliest gut colonizers of breast-fed infants, have an adapted functional capacity to metabolize various HMO structures. This ability is typically observed in infant-associated bifidobacteria, as opposed to bifidobacteria associated with a mature microbiota. In recent years, information has been gleaned regarding how these infant-associated bifidobacteria as well as certain other taxa are able to assimilate HMOs, including the mechanistic strategies enabling their acquisition and consumption. Additionally, complex metabolic interactions occur between microbes facilitated by HMOs, including the utilization of breakdown products released from HMO degradation. Interest in HMO-mediated changes in microbial composition and function has been the focal point of numerous studies, in recent times fueled by the availability of individual biosynthetic HMOs, some of which are now commonly included in infant formula. In this review, we outline the main HMO assimilatory and catabolic strategies employed by infant-associated bifidobacteria, discuss other taxa that exhibit breast milk glycan degradation capacity, and cover HMO-supported cross-feeding interactions and related metabolites that have been described thus far.

Patterns of Human Milk Oligosaccharides in Mature Milk Are Associated with Certain Gut Microbiota in Infants

“…However, a negative association between P2 and B. breve was observed in this study. The inconsistencies may indicate that other factors beyond HMOs such as host-secreted glycans [55] or colonisation order of the Bifidobacterium species [56] have a greater influence on the infant gut microbiota. Furthermore, other commensal microbiota such as Bacteroides and Lactobacilli also possess the ability to degrade HMOs [57] and the competitive colonisation between these genera may also have an impact on our results.…”

Milk Bioactive Compounds and Gut Microbiota Modulation: The Role of Whey Proteins and Milk Oligosaccharides

“…Apart from the role exerted by its own microbiota, which contributes to a healthy microbial diversification of the gut microbiota of newborns [ 65 , 66 ], the bioactive components of milk, especially oligosaccharides and whey proteins such as lactoferrin, lysozyme, and α-lactalbumin, have been shown to play a crucial role in shaping the gut microbiota from birth to adulthood [ 67 , 68 ]. Indeed, studies have reported the role of human and cow’s milk constituents in promoting the growth of beneficial probiotic bacteria, including B. infantis , B. Pennsylvanicus , B. longum , B. bifidum , and B. breve [ 69 , 70 , 71 , 72 ].…”