Screening of antibiotic activity by agar well diffusion method
Antibacterial activity was assayed in duplicate by agar well diffusion method. Wells of 5 mm diameter were punched in nutrient agar plates seeded with test bacterial organisms, which corresponded to a 0.5 McFarland turbidity standard solution. Yeast extract, peptone and dextrose (YEPD) medium instead of nutrient agar was used for Candida. Plates were incubated for 96 h at optimal temperature for the test organism. The inhibition zones around the disks were measured. Crude cell free supernatant (20 ml) of overnight fungal culture of 16—18 h growth was added in each well. Plates were then incubated overnight at 37 8C for 24 h. The inhibitory activity was detected as a zone of clearing in the turbid medium around the wells containing antibacterial activity (positive samples). The diameter of the clearing zones in (mm) formed a semiquantitative method of determination of the inhibition effect at specific concentration of the antibacterial compound.