.Micro dilution assay
The minimal inhibition concentration (MIC) values were determined for the bacteria determined as sensitive to the EO in disc diffusion assay. The inocula of bacteria were prepared from 12 h broth cultures and cultures were adjusted to 0.5 McFarland Standard turbidity. The EO
concentrations were prepared between 500 μl/ml to 7.81 μl/ml and tested in 10 ml sterile test tubes containing tryptic soy broth (TSB). MIC values of
the EO against bacterial strains were determined
based on a micro-well dilution method 15, 16. The
96-well plates were prepared by dispensing into
each well 95 μl of tryptic soy broth and 5 μl of the
inoculum. Then 100 μl from EO at all the prepared concentrations were added into the wells.
Negative control was prepared as the last well
containing 195 μl tryptic soy broth without EO
and 5 μl of the bacteria. The concentrations of
Maxipime (Bristol-Myers Squibb) between 500-
7.81 μl were prepared in TSB and used as positive control. The plate was mixed on plate shaker
at 300 rpm for 20 s, and incubated at 27°C for 24
h. Bacterial growth was determined by absorbance at 600 nm using the EL×800 universal
microplate reader. The EO was tested against all
the bacteria for three times. The MIC was defined as the lowest concentration of the compounds to inhibit the growth of microorganisms 12,17