Characterization of Bifidobacterium bifidum growth and metabolism on whey protein phospholipid concentrate

Whey protein phospholipid concentrate (WPPC) is a co-product generated during the manufacture of whey protein isolate. Whey protein phospholipid concentrate is depleted of simple sugars but contains numerous glycoconjugates embedded in the milk fat globule membrane, suggesting this fraction may serve as a carbon source for growth of bifidobacteria commonly enriched in breastfed infants. In this work, we demonstrate that WPPC can serve as a sole carbon source for the growth of Bifidobacterium bifidum, a species common to the breastfed infant and routinely used as a probiotic. Growth on WPPC fractions resulted in expression of key extracellular glycosyl hydrolases in B. bifidum associated with the catabolism of glycoproteins. Interestingly, this included induction of fucosidase genes in B. bifidum linked to catabolism of fucosylated human milk oligosaccharides even though the WPPC glycan possesses little fucose. Additional growth studies revealed that WPPC-glycan components N-acetylglucosamine or N-acetylgalactosamine were required for pre-activation of B. bifidum toward rapid growth on fucosylated human milk oligosaccharides. Growth on WPPC fractions also resulted in expression of extracellular sialidases in B. bifidum which promoted a consistent release of sialic acid, a well-known component of bovine milk oligosaccharides and glycoconjugates with potential effects on gut microbial ecology and host cognition. These studies suggest WPPC may serve as a promising bioactive component to facilitate probiotic activity for use in infant formulas and other synbiotic applications.