Minimum inhibitory concentration (MIC). MIC was determined by both agar well diffusion and broth dilution methods.
In the well diffusion method, the surface of Petri dishes containing 25 ml of MuellerHinton agar was seeded individually with bacterial suspensions (108 CFU/ml) with a sterile cotton swab.Wells with 7 mm diameter were created by punching a stainless steel cylinder on to the agar plates and removing the agar to form a well.
Finally, 80 ml aliquots of each prepared sample (100, 50, 25,12.5, and 6.25 ppm) were placed individually in two wells. The prepared Petridishes were incubated at 35C for 20 h, and diameters of inhibition zones (i.e., areas surrounding the test samples where bacteria growth is inhibited or not) were determined.