Abstract: The aim of this study is to investigate in-vitro antimicrobial eff ects of the essential oils from oregano (Origanum
acutidens and Origanum rotundifolium) and thyme (Th ymus sipyleus subsp. sipyleus var. rosulans). Th e chemical
composition and antimicrobial attributes of the essential oils obtained from the aerial parts of the plants, of which
there were 3 Lamiaceae species, have been studied. A total of 43 microorganisms, including 26 bacteria, 14 fungi, and
3 yeasts species, have been studied by using disc-diff usion (DD) and minimal inhibition concentration (MIC) methods.
Mean inhibition zones and MIC values of bacterial strains varied from 8 and 72 mm to 7.8 and 500 μg mL-1, respectively.
Th e maximal inhibition zones and MIC values of the yeast and fungi species sensitive to the essential oils were 8-74 mm
and 7.8-500 μg mL-1, respectively. Th e susceptibility of the tested microorganisms varied depending on the essential
oil composition. In general, the essential oils showed higher DD values than tested antibiotics. Th e essential oils of
oregano and thyme may be considered a potential source of a natural antimicrobial for the food industry aft er testing
the toxic and irritating eff ects on humans.