The minimum inhibitory concentration
(MIC) of the essential oils was determined
by the two-fold serial dilution technique
(Baker et al., 1980). Dilutions of the essential
oil were prepared in a Mueller-Hinton
broth (Hi Media, Mumbai) ranging from
0.06 to 125 µl/ml. To each tube, 0.5 ml of
the inoculum containing approximately 108
CFU/ml microorganisms was added. A control
test, containing inoculated broth supplemented
with only DMSO under identical
conditions with gentamicin, was also performed
as reference. All the tubes were
then incubated at 37 °C for 24 h and examined
for any evidence of growth.