Human milk oligosaccharide-sharing by a consortium of infant derived Bifidobacterium species

Bifidobacteria are associated with a host of health benefits and are typically dominant in the gut microbiota of healthy, breast-fed infants. A key adaptation, facilitating the establishment of these species, is their ability to consume particular sugars, known as human milk oligosaccharides (HMO), which are abundantly found in breastmilk. In the current study, we aimed to characterise the co-operative metabolism of four commercial infant-derived bifidobacteria (Bifidobacterium bifidum R0071, Bifidobacterium breve M-16V, Bifidobacterium infantis R0033, and Bifidobacterium infantis M-63) when grown on HMO. Three different HMO substrates (2'-fucosyllactose alone and oligosaccharides isolated from human milk representing non-secretor and secretor status) were employed. The four-strain combination resulted in increased bifidobacterial numbers (> 21%) in comparison to single strain cultivation. The relative abundance of B. breve increased by > 30% during co-cultivation with the other strains despite demonstrating limited ability to assimilate HMO in mono-culture. HPLC analysis revealed strain-level variations in HMO consumption. Metabolomics confirmed the production of formate, acetate, 1,2-propanediol, and lactate with an overall increase in such metabolites during co-cultivation. These results support the concept of positive co-operation between multiple bifidobacterial strains during HMO utilisation which may result in higher cell numbers and a potentially healthier balance of metabolites.