Surfactin and its Antibacterial Mechanism on Staphylococcus Aureus and Application in Pork Preservation

This study investigated the antibacterial capacity and mechanism of surfactin (prepared by fermenting soybean meal with Bacillus subtilis SOPC5) against Staphylococcus aureus by examining its influences on the bacterial morphology, cell wall and membrane, as well as metabolic activity. The efficiency of surfactin in pork preservation was also investigated. HPLC-MS analysis showed that surfactin’s purity reached 97.4%, containing five congeners. The minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) of surfactin against S. aureus were 1.6 and 3.2 mg/mL, respectively. The result of scanning electron microscopy observation revealed that 4 h of surfactin exposure resulted in deformation and even collapse of S. aureus. AKP assay, membrane potential analysis, extracellular protein and nucleic acid content measurement, and PI staining intensity assay showed that surfactin destroyed the cell wall and cell membrane of S. aureus. Decreases in iodonitrotetrazolium chloride levels and ATP enzyme activity indicated that surfactin could inhibit the metabolic ability of S. aureus. Furthermore, surfactin demonstrated an excellent antibacterial action on S. aureus within 5 days of pork storage without changing its texture. These findings suggest that sufactin has a great application potential in pork preservation.