2.7.1. Antibacterial Activity

The antibacterial activity of biosynthesized B. tomentosa Linn flower-powder extract-derived AgNPs was investigated against Gram-negative (E. coli) and Gram-positive (S. aureus) bacterial pathogens using agar disk diffusion [28,56,61,65,66]. Briefly, a nutrient agar medium was prepared in a Petri dish and the bacterial cultures were swabbed on test media with a sterile cotton swab. The discs were dipped with the following four components (30 μL): (i) biosynthesized AgNPs, (ii) B. tomentosa Linn flower powder extract, (iii) AgNO₃ solution, and (iv) standard antibiotic solutions (chloramphenicol, 30 µg/mL). The dried discs were pressed gently over the surface of the culture-swabbed medium at equal distances to avoid overlapping of the inhibition zones. The plates were then incubated at 37 °C for 24 h. After incubation, the antibacterial activity of the biosynthesized AgNPs was evaluated according to the diameters of the clear inhibition zones [67].