Abstract: In this study, it was found that when co-cultured with Bacillus cereus, the growth of Staphylococcus aureus was inhibited. The antimicrobial peptide DB16 (RKLLQFAKKLGIVFTK) was predicted and selected from the ATP-dependent RNA helicase of B. cereus by bioinformatics. The minimum inhibitory concentration (MIC) of the antimicrobial peptide DB16 against S. aureus was 31.25 μg/mL, which could completely inhibit the growth of S. aureus within 0.5 h. DB16 presented a random coiled structure in phosphate buffered saline (PBS), and turned into an α-helix structure in sodium dodecyl sulfate (SDS). Fluorescence probe, flow cytometry, transmission electron microscopy (TEM), DNA gel electrophoresis and circular dichroism (CD) spectroscopy were used to explore the antibacterial mechanism of DB16 against S. aureus. The results showed that the antibacterial peptide DB16 could change the permeability of the bacterial cell membrane, thereby causing the leakage of cellular contents, while entering the cells to combine with the genomic DNA of S. aureus, affecting normal DNA replication, and finally inhibiting the growth and reproduction of bacteria. In addition, DB16 at 8 × MIC showed no hemolysis on mammalian red blood cells. In conclusion, the antimicrobial peptide DB16 from B. cereus has great potential for the prevention and control of S. aureus.

Key words: Bacillus cereus; Staphylococcus aureus; antimicrobial peptide; cell membrane permeability; DNA binding mechanism