In the present study, Ag nanoparticles (NPs) were synthesized by eco-friendly method. Design and analysis of Taguchi experiments was done by the Qualitek-4 software. Effect of AgNO3 concentration (0.1, 0.01 and 0.001 M), incubation and culturing time (48, 72, 96 hours) as three different levels were measured as three major factors in NPs biosynthesis. We carried out biosynthesis of NPs through cell-free culture supernatant of Bacillus sp. HAI4. X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FT-IR), UltravioletVisible spectroscopy (UV) and Scanning Electron Microscopy (SEM) techniques are applied for NP characterization. It was demonstrated the average particles size was 33/264 nm with spherical shapes. Also, for evaluating of antibacterial effects, maximum zone of inhibition, two important multidrug resistant pathogenesis bacteria, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 43300 were used. Three levels of Ag NPs had antibacterial effect on these bacteria (1, 1 and 0.5 cm for E.coli and 1.1, 1.1 and 1.1 for S.aureus) but there was no significant difference between three levels.
Key words: Ag nanoparticles, Bacillus sp. HAI4, Qualitek-4 software, UV spectroscopy, SEM, Staphylococcus aureus.