Antibiofilm mechanism of a novel milk-derived antimicrobial peptide against Staphylococcus aureus by downregulating agr quorum sensing system

Staphylococcus aureus has emerged as a serious threat to food safety owing to biofilm formation. The study aimed to examine the antibiofilm mechanism of a novel milk-derived antimicrobial peptide BCp12 against it.Antibiofilm activity of BCp12 was studied by crystal violet staining, MTT assay, motility, SEM and CLSM. TMT proteome, real-time PCR and molecular docking in silico were conducted to evaluate the mechanism of BCp12 against S. aureus biofilm. The results showed that BCp12 had significant antibiofilm activity at 1 × MIC and sub-MIC. BCp12 induced the dispersion of structure of S. aureus biofilm BCp12 inhibited the movement of S. aureus. A total of 703 proteins were downregulated and 334 proteins were upregulated after BCp12 treatment. The proteins (agrA, agrB, agrC and psmβ) of the QS systems were downregulated. Additionally, the expression of the agr-related genes, agrA, agrB, agrC and psmβ, was downregulated. BCp12 was bound to the receptor proteins agrA and agrC through hydrogen bonds and π-π bonds.The results showed the antibiofilm activity of BCp12 and it inhibits the biofilm formation by interfering agr QS system.BCp12 has the potential to be a novel antibiofilm agent against S. aureus biofilm and used in the food industry.