2.4.2. Colony count method
Colonies of S. aureus and E. coli obtained from an overnight culture were suspended in Luria Broth and the turbidity was adjusted to 0.5 McFarland standards. The samples (∼20 mg) were placed in contact with 6 mL bacterial suspension in Luria Broth having 105 CFU mL−1. All suspensions were vortexed and incubated at 37 °C for 24 h. The suspensions were vortexed again and dilutions were prepared and colonies were counted by the spread plate method. The inoculum (200 μL) was uniformly spread on nutrient agar plate using a sterile cotton swab. Plates were incubated at 37 °C and the colonies were counted after 24 h. All experiments were conducted under sterile conditions. Antibacterial efficiency (R) was calculated according to the following equation: