Characterization and TLC-bioautographic detection of essential oils from someThymustaxa. Determination of the activity of the oils and their components against plant pathogenic bacteria

The chemical composition of the oils of four thyme (Lamiaceae) chemotypes ( Thymus vulgaris L., Thymus serpyllum L., Thymus x citriodorus (Pers.) Schreb., and Thymus x citriodorus “Archer’s Gold”) has been determined by gas chromatography (GC). Thymol was the main component of the oils of Thymus vulgaris and Thymus serpyllum , geraniol was the main component of the oil of Thymus x citriodorus , and carvacrol was the main component of the oil of Thymus x citriodorus “Archer’s Gold”. The bioactivity of the volatile oil of Thymus vulgaris and of the three main components of the oils against Gram negative plant pathogenic bacteria was examined by direct bioautography. They had an inhibitory effect on all of the test microorganisms. Two bacterial strains ( Xanthomonas campestris pv. vesicatoria and Pseudomonas syringae pv. phaseolicola ) were most sensitive in the bioautographic system and use of these bacteria would considerably shorten the process of bioautographic detection. The two antibiotics gentamycin and streptomycin were used as controls.