Bovine milk glycoproteins concentration influences bacterial growth and anti-pathogenic bioactivities relevant to the infant gut in vitro

Milk whey glycoproteins lactoferrin (LF) and α-lactalbumin (α-Lac) demonstrate prebiotic and antibacterial effects but concentration-dependent effects are not well studied, and osteopontin (OPN) effects directly on bacteria are underinvestigated. In this study, bovine milk LF, α-Lac and OPN exhibited concentration-dependent and selective prebiotic and antibacterial effects on infant gut relevant commensal lactobacilli and pathogens. Bovine milk LF was selectively prebiotic for Lacticaseibacillus rhamnosus at 3 mg/mL (human milk colostrum (HMC) concentration) and 0.7 mg/mL (mature human milk (MHM) concentration), and inhibitory for MRSA and enteropathogenic Escherichia coli (EPEC). Bovine milk OPN increased L. rhamnosus growth and Lacticaseibacillus paracasei only at 0.2 mg/mL (MHM concentration) and 0.7 mg/mL (HMC concentration), but inhibited Levilactobacillus brevis, MRSA, and EPEC. Bovine milk α-Lac selectively supported L. paracasei growth. Unsupplemented L. rhamnosus culture inhibited MRSA growth, but LF-supplemented at 0.7 mg/mL increased MRSA death. L. rhamnosus utilisation of LF protein and N-linked glycans while linked to the protein backbone was demonstrated, and these metabolites may have contributed to the anti-MRSA effects. The complexity of changing milk glycoprotein concentrations was demonstrated, offering potential insights into the developing gut microbiome and designing formulations.