Synthesis of silver nanoparticles by Bacteria, plant and Chemical method and evaluation of their antimicrobial effects

The emergence of antibiotic resistance has a serious challenge to the control and treatment of pathogenic bacterial infections. Nanotechnology and the use of nanoparticles are some of the most effective approaches to overcome this topic. Silver nanoparticles have been studied as an antibacterial agent more than other nanoparticles by researchers. In this study, the antibacterial effect of silver nanoparticles synthesized by three methods including; bacterial, plant extract, and chemical procedure were compared. So, we synthesized silver nanoparticles using the supernatant of Bacillus spp. with Zarshouran gold mine source, oregano extract, and sodium borohydride chemical. Then, the minimum inhibitory concentrations (MIC) of silver nanoparticles against Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa were investigated. Comparison of the MIC results showed that the antibacterial effect of nanoparticles synthesized with Bacillus spp. was more than fivefold higher than the plant extract and chemical synthesis method. We showed that the minimum inhibitory concentration of nanoparticles synthesized with Bacillus spp., oregano extract, and sodium borohydride ranged from (1.4-5.6 μg / mL), (5.6-22.5 μg / mL), and (22.5-45 μg / mL), respectively.