Investigation of antimicrobial activity of essential oils of several Macedonian Thymus L. species (Lamiaceae).

Antimicrobial activity of twenty specimens of essential oils of eleven Thymus species, naturally occurring in the Macedonian flora, was investigated by agar diffusion and broth dilution methods. Inhibition of growth and microbicidal action was examined on three Gram positive bacteria (Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae). In spite of wide variability in essential oil composition, ranging from traces of thymol to the amount of about 50% thymol in oils, all examined samples of Thymus essential oil possessed strong antibacterial activity. Zones of inhibition of growth (for 25% dilution of oils) was from 10-54 mm in diameters. MICs ranging from 0.012-0.1% while MMCs were from 0.025-0.4% for essential oils that contained large amounts of phenols and 0.2-1.6% for those which contained traces of phenols and large amounts of geraniol, linalool and (Z + E)-citral.