Mechanisms and Strategies of Human Milk Oligosaccharides Utilization by Gut Bacteria: Implications for Intestinal Health

Human milk oligosaccharides (HMOs) are biologically active carbohydrates that play a pivotal role in infant health, with their significant prebiotic properties contributing to the maintenance of intestinal health. In vitro and in vivo studies have shown that Bifidobacterium is the dominant bacterial group in the intestinal microbiota of neonates, while the abundance of Bacteroides changes significantly with the growth stage – it usually increases gradually and forms a certain scale only after infants are introduced to solid foods. They capture and degrade HMOs structures through various molecular mechanisms, thereby promoting the production of short-chain fatty acids (SCFAs), which are crucial for maintaining intestinal homeostasis. This paper reviews the potential mechanisms and strategies by which beneficial gut bacteria utilize HMOs, with a focus on elaborating the HMOs-degrading mechanisms of gut microorganisms such as Bifidobacteria, B. kashiwanohense APCKJ, B. breve UCC2003, and Bifidobacterium longum subsp. Infantis Bi-26. It also describes the model of nitrogen metabolism in the utilization of HMOs by gut microorganisms, including nitrogen metabolism, carbohydrate metabolism, and peptidoglycan synthesis pathways.