A novel milk-derived peptide effectively inhibits Staphylococcus aureus: Interferes with cell wall synthesis, peptidoglycan biosynthesis disruption reaction mechanism, and its application in real milk system

BCp12, a novel antimicrobial agent derived from buffalo milk, poses superior antimicrobial activity against Staphylococcus aureus. In the present study, the effect of BCp12 on the cell wall synthesis and molecular pathways of Staphylococcus aureus was studied by the CLSM, SEM and proteomics analyses to facilitate the development of this novel antimicrobial peptide. The results demonstrated that BCp12 significantly damaged the cell wall integrity and resulted in subsequent pore formation. A total of 915 DEPs (Differentially Expressed Proteins) were analyzed by the quantitative proteome analysis, among which most DEPs possessed different molecular functions and were involved in different molecular pathways in the bioinformatics-based tools. These DEPs (MurC, MurD, MurE, MurF, MurG) and the target genes were verified by molecular docking and quantitative real-time PCR. Notably, most DEPs participated in the peptidoglycan biosynthesis pathways, DNA mismatch repair, and glutamine and glutamate metabolites. The combined results of ultrastructure observations, genes, and protein expression analysis revealed that BCp12 effectively killed S. aureus in milk. Overall, BCp12 provides a promising application prospect in food preservation due to its dual-targeted effects against S. aureus in milk.