Evaluation of Antibacterial Activity of Various Commercial Essential Oils

Essential oils and their components are becoming increasingly popular as naturally occurring antimicrobial agents. In this work the chemical composition and the antibacterial properties of the essential oils of rosemary (Rosmarinus officinalis), lemon (Citrus limonum), oregano (Corydothymus capitatus) and thyme (Thymus vulgaris) were determined. The essential oil components were identified by GC/MS analysis. The antibacterial activity of the oils was investigated in order to evaluate its efficacy against a panel of standard reference strains, using disc diffusion and minimum inhibitory concentration (MIC) methods. The GC/MS analysis showed that the major constituents of the oils were monoterpene hydrocarbons and phenolic monoterpenes, but the concentration of these compounds varied greatly among the oils examined. The results of the antibacterial assay showed that Corydothymus capitatus and Thymus vulgaris have the strongest antibacterial activity against all microorganisms tested. The MIC values obtained in the presence of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Salmonella arizonae were ≤ 0.25% (v/v) for oregano and thyme essential oils