2.4.5.3. Determination of MIC.
To determine theMIC of each spice extract,
a broth micro-dilution methodwas performed according to themethod
of Jorgensen and Turnidge (2007). Ninety-six-well culture plates
were prepared, and serial two-fold dilutions of the extracts were
dispensed into the plate wells. The volume of dispensed extract
was 0.1 ml per well in the concentration range of 50 mg/ml to
5 mg/ml. The concentration values were expressed on the basis of
lyophilized materials dissolved in water. The same volume (0.1 ml) of
overnight bacterial culture at a density of 105 CFU/ml was added to
the wells, and the culture plates were placed in an incubator set at
37 °C for 24 h. The lowest concentration of the plant extract required
to inhibit visible growth of the tested microorganism was designated
as the MIC.