The specific antibacterial effect of the Salvia oil nanoliposomes against Staphylococcus aureus biofilms on milk container

• Salvia oil showed an excellent antibacterial activity against Staphylococcus aureus biofilms on milk container.
• Controlled release of SO from nanoliposomes was successfully achieved by α-toxin secreted from S. aureus.
• The anti-biofilm action time of liposome-entrapped Salvia oil has been prolonged significantly.

The Staphylococcus aureus (S. aureus) biofilm on container is the main source of microbial contamination in milk. In this study, the nanoliposomes encapsulating Salvia oil (SO) has been prepared. Based on the damage effect of pore-forming toxin on cell membrane, α-toxin secreted from S. aureus has been used to trigger the release of SO from nanoliposomes to achieve antibacterial effect on S. aureus biofilm on milk container. Firstly, the minimum biofilm eradication concentration (MBEC) and biofilms time-dependent killing of SO were tested. The results showed that the MBEC of SO against S. aureus biofilms was 0.2% and SO effectively eradicated the biofilms after treating for 4 h. Subsequently, SO was encapsulated into nanoliposomes in order to increase its stability. The particle size, poly dispersity index (PDI), zeta potential, pH, turbidity, and entrapment efficiency of SO nanoliposomes were analyzed systematically. Gas chromatography–mass spectrometry (GC–MS) has been utilized to observe the controlled release of SO form nanoliposomes incubated with S. aureus. The scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) images have also visually showed that SO nanoliposomes have high anti-biofilm activity against S. aureus biofilms on milk container.