Green synthesis of silver nanoparticles using soil bacteria and its antibacterial potential

Silver nanoparticles (AgNPs) are a well-known antimicrobial agent used in disease management and commercial production of biomedicine. Nowadays, biological synthesis of AgNPs is a green way to replace conventional chemical methods. In the present study, AgNPs were prepared using the cell-free supernatant of a bacterial isolate, which was then identified as Enterobacter mori strain C29(1)CG by 16S ribosomal RNA molecular sequencing. Based on optical color shift, the biosynthesized AgNPs were characterized using Ultraviolet (UV)-visible spectroscopy, X-ray diffraction (XRD) pattern, Fourier Transform Infrared (FTIR), scanning electron microscopy (SEM), and energy dispersive X (EDX) analysis. These nanoparticles showed a characteristic absorption peak between 400 and 500 nm in the UV-visible spectrum. The crystalline nature of AgNPs was estimated by XRD. FTIR reveals the functional group present in the biosynthesized AgNP sample. SEM image and EDX analysis revealed the formation of irregular spherical nanoparticles. Furthermore, the antimicrobial activity of AgNPs was also assessed against three test pathogens-Staphylococcus aureus, Streptococcus mutans, and Klebsiella pneumoniae by measuring the inhibition zone. Hereby, the findings revealed that these biosynthesized AgNPs showed maximum zone of inhibition against S. aureus and can be considered a powerful antimicrobial agent against pathogenic bacteria.