Abstract
The essential oils of four lines of Origanum vulgare L. subsp. hirtum (Link) Ietswaart cultivated in Hungary were analysed by GC and GC-MS methods. These oils were found to contain carvacrol, γ-terpinene and p-cymene as main constituents. The antimicrobial activities of the various oils and their authentic individual components were tested on Gram-positive and Gram-negative bacterial strains, two Saccharomyces cerevisiae strains and two Candida albicans strains. No difference in sensitivity was found between Escherichia coli, Staphylococcus epidermidis and the yeast strains tested, but there were marked differences in sensitivity between the proton pump-deficient mutant of E. coli and its wild type as regards the growth inhibition and MIC values.