ANTIBACTERIAL AND ANTI-YEAST EFFECTS OF SOME ESSENTIAL OILS

Essential oils from aromatic plants of Ledum palustre L. and Mentha piperita L. were extracted using steam distillation and the antimicrobial effects were evaluated alone and in combinations against food-borne pathogens of Gram-positive and Gram-negative bacteria and food related-yeasts (Bacillus subtilis, Escherichia coli, Saccharomyces cerevisiae, Schizosaccharomyce spombe, and Geotrichum candidum). Essential oils from two aromatic plants used in this study showed the antimicrobial activity against bacteria and yeast, which was found to be concentration dependent. The effects of Ledum palustre L. and Mentha piperita L. plants essential oils against yeast and Gram-negative bacteria at concentrations of 0.5 ul/ml and 0.25 ul/ml extended lag phase or adaptation phase by 48 hours, respectively. Gram-positive bacteria were found to be susceptible to the studied two plants essential oils. When the effects of antimicrobial activity of two essential oils were tested in combination against bacteria and yeast in vitro, the MIC value was in the range of 0.125-0.5 ul/ml and showed synergistic activity against E.coli and additive values against B.subtilis and S.cerevisiae.