Antibacterial assay test by disc diffusion method

The antibacterial assays were performed using standard disc diffusion method (Kirby-Bauer method) in Nutrient agar (NA) media. The fresh overnight culture of inoculum (200 μl) of Ef was spread onto solidified NA plates. AgNPs was purified by centrifuging supernatant at 10,000 rpm followed up by washing it twice with sterile water. Sterile paper discs were made of Whatman filter paper (Grade-1) of 4 mm diameter, impregnated with standard antibiotic concentrations and combinations and nanoparticles solution and a control disc (sterile paper disc dipped in water) were placed on each plate. The cultured agar plates were incubated at 37°C for 24 h. After 24 h of incubation, inhibition zones were observed.