Antimicrobial activity of two mentha species essential oil and its dependence on different origin and chemical diversity

Genus Mentha presents group of plants which are the most studied in family Lamiaceae. Aboveground parts are used for different purposes in pharmacy, food industry or confectionery. Most important is natural product extracted from leaves - essential oil (EO). The aim of presented experiment was to demonstrate different chemotype and compare antibacterial activity of two Mentha species EO. Plant samples were obtained from various environments – from Slovakia and from Italy. Dominant compounds were determined by GC/MS. The results showed high amount of menthol and menthone in tested Slovak peppermint EO. On the other hand, carvone and 1,8-cineole were determinate as dominant compounds in Italian spearmint EO. The antimicrobial activity of the EO was investigated by disc diffusion and broth micro dilution methods. EO was evaluated for their antibacterial activity against 7 microorganisms: Enterobacter cloacae, Salmonella spp., Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes. The determination results of antibacterial activity by agar disk diffusion method ranged from 7 to 14 mm of the growth inhibition zone. MIC of tested mint EO varied from 0.625 to 2.5 μg/mL. In addition, both EO showed relatively the same antibacterial activity against the selected Gram-negative bacteria. However, there is a variation in the antibacterial activity against Gram-positive bacteria.