A novel endogenous antimicrobial peptide MP-4 derived from koumiss of Inner Mongolia by peptidomics, and effects on Staphylococcus aureus

Koumiss is known as a traditional milk-based beverage with high nutritional value and antimicrobial potential. In this study, we investigated the antibacterial effects of koumiss-derived antimicrobial peptides against Staphylococcus aureus. Then, we used peptidomics to analyze and identify 2381 peptides from mare's milk and koumiss, of which 53.25% were significantly different before and after fermentation, and these peptides were mainly derived from caseins. Among the identified peptides, five new antimicrobial peptides with high antimicrobial potential, as measured by the scores of predicted peptide sequences in the antimicrobial peptide database, and validation of their antimicrobial activity and stability. MP-4 was found to have antimicrobial activity, and it exerted significant and stable antibacterial effects. The antimicrobial peptide MP-4 could inhibit Staphylococcus aureus by changing its morphology and killing it via the induction of protein leakage. Therefore, it can be concluded that MP-4 is a novel antimicrobial peptide derived from koumiss that has good antibacterial properties against Staphylococcus aureus. Our study provides a theoretical basis for the application of koumiss-derived peptides.