The essential oils obtained from two mint species, Mentha pulegium and
Mentha spicata, exhibited antimicrobial properties against eight stra
ins of Gram-positive and Gram-negative bacteria. The essential oils of
these mint species at high concentration (1/100 dilution) were extrem
ely bactericidal, whereas lower concentrations (1/1000) caused a dose-
dependent decrease in bacterial growth rates. The main p-menthane comp
onents of the tested essential oils showed a variable degree of antimi
crobial activity not only between different bacterial strains but also
between different strains of the same bacteria.