Chemical compositions and antimicrobial activities of oregano and thyme essential oils

The aim of this study was to evaluate the chemical composition and antimicrobial activity of essential oils of thyme and oregano. Gas chromatography with mass spectrometry (GC-MS) was used to determine the chemical structure of essential oils and their dominant components. Antimicrobial activity of essential oils was tested against standardized bacterial and fungal cultures: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Candida albicans ATCC 24433, Enterococcus faecalis ATCC 25929, using the agar diffusion method with wells. Minimum inhibitory concentration (MIC) for essential oils determined by the broth dilution method and valued in the range of 3 - 5 mu l/ml, depends on the essential oil and bacteria and C.albicans tested. Both essential oils provided strong antibacterial activity for the tested microorganisms. The essential oil of thyme was especially recognized. These experiments aimed at showing the in vitro antimicrobial activity of the selected essential oils in order to find out the most potential essential oil that would be an objective in further investigation on chitosan drug delivery system with controlled release of antimicrobial essential oil.