Antibacterial Mechanism of Thymol: Cell Membrane Damage and Genomic DNA Binding of Staphylococcus Aureus

Thymol is a natural ingredient used as flavor or preservative agent in food products. The antimicrobial mechanism of thymol against Staphylococcus aureus ATCC 43300 (S. aureus) was investigated in this study. A total of 15 membrane fatty acids were identified in S. aureus cells by gas chromatography-mass spectrometry. Exposure to thymol at low concentrations induced an obvious decrease in the level of branched chain fatty acids, including iso C15:0, anteiso C15:0 and anteiso C17:0. Membrane permeability assay and morphological image showed that thymol at higher levels affected S. aureus cell membrane integrity, which may decrease cell viability. Moreover, genomic DNA binding properties of thymol were also investigated using multi-spectroscopic techniques, docking and atomic force microscopy. The results indicated that thymol bound to the minor groove of DNA, resulting in mild destabilization of the DNA secondary structure, and making DNA molecules to be aggregated.