Zinc oxide nanoparticles (ZnO-NPs) were successfully synthesized using leaf extracts of B. dalzielii and characterized by UV-visible spectroscopy, which revealed a strong absorption peak at 374 nm, indicating the formation of ZnO-NPs. The antimicrobial activity of the synthesized ZnO-NPs was evaluated against clinical and standard strains of S. typhi, E. coli, P. aeruginosa, A. niger, and A. flavus. The results demonstrated significant antimicrobial efficacy, with inhibition zone diameters ranging from 15 to 23 mm at concentrations between 50 and 100 mg. The minimum inhibitory concentration (MIC) was determined to be 60 mg for bacteria and 70 mg for fungi. These findings suggest that ZnO nanoparticles synthesized from B. dalzielii leaf extracts hold great potential as a promising natural source of antimicrobial agents for treating infections caused by the tested pathogens.

Keywords: Zinc oxide nanoparticles, UV-visible spectroscopy, antimicrobial activity, B. dalzielii and bacteria.