Evidence for the influence of the milk fat globule membrane on bifidobacteria metabolism and cell surface properties

<i>Bifidobacterium</i>, a genus commonly found in the microbiome of healthy infants, has been demonstrated to exert various beneficial effects on the gastrointestinal tract, contributing to overall health. Notably, these bacteria possess the ability to use complex glycoconjugates as nutrients, which holds importance for breast-fed infants, as human milk contains substantial quantities of these glycoconjugates. However, the underlying mechanisms of action of these beneficial properties remain largely unexplored. This study presents an alternative perspective on the nutrients in the diet that could potentially support the maintenance of a healthy <i>Bifidobacterium</i> population. We present evidence suggesting that the presence of milk fat globule membrane (MFGM), a component shared by all mammalian milk, significantly alters the metabolism of these bacteria. This alteration is reflected in the production of exopolysaccharides on the surface and secretome of the bacteria fed MFGM, whereas the absence of this component does not result in such changes. To substantiate this hypothesis, we employed proteomic and physicochemical methods, culminating in the evidence of the MFGM layer through electron microscopy.