The specific antibacterial activity of liposome-encapsulated Clove oil and its application in tofu

• Clove oil could damage the integrity of cell membrane, leading to the losses of intracellular constituents and cell death.
• Controlled release of Clove oil from liposome was successfully achieved by PFTs secreted from S. aureus.
• Liposome-encapsulated Clove oil could efficiently inhibit S. aureus in tofu.

In this study, the antibacterial activities of Clove oil and liposome-encapsulated Clove oil were investigated. First, the antibacterial activity of Clove oil demonstrated that the essential oil exhibited favorable antimicrobial activity for both Escherichia coli and Staphylococcus aureus. However, a setback of using Clove oil as a disinfectant is its low chemical stability. Then Clove oil was incorporated into a liposome formulation to increase its stability. The optimal polydispersity index (PDI) (0.196), Zeta potential (−24.5 mV) and entrapment efficiency (20.41%) of liposome were obtained at the concentration of Clove oil to 5.0 mg/mL. In addition, selective antimicrobial activity for S. aureus by utilizing pore-forming toxins (PFTs) to activate Clove oil release from liposome was observed. By contrast, liposome-encapsulated Clove oil has no effect on E. coli that doesn't secrete PFTs because antimicrobial component can't reach bacteria. Gas chromatography (GC) assay found that when liposome met S. aureus that secrete PFTs, PFTs would insert into the liposome membranes and form pores, through which the encapsulated Clove oil was released. Besides, liposome-encapsulated Clove oil exhibited efficient antimicrobial activity for S. aureus in tofu.