Microbial synthesis of silver nanoparticles using Lactobacillus plantarum for antioxidant, antibacterial activities

[Display omitted] •Microbial synthesis of silver nanoparticles (AgNPs) using Lactobacillus plantarum was successfully synthesized.•Various techniques were proposed to fully characterize the biosynthesized AgNPs.•AgNPs effectively demonstrate outstanding antioxidant, antibacterial activities. In this study, we proposed a method for producing stable silver nanoparticles (AgNPs) from Lactobacillus plantarum culture supernatant that is environmentally friendly and cost-effective. The biosynthesized AgNPs were characterized using various techniques, including UV–visible spectroscopy, Fourier Transform Infrared spectroscopy, Scanning Electron Microscopy, Energy Dispersive X-ray, and X-ray diffraction. According to the findings, the characterization verified that AgNPs have spherical and non-uniform contours with average diameters of 40-50 nm. The antioxidant and antibacterial activities of biosynthesized AgNPs were successfully investigated. In particular, the antioxidant activities had been evaluated using 1,1′-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2) methods. In DPPH and H2O2 scavenging assays, synthesized AgNPs exhibited very strong antioxidant properties, with an antioxidant potential of 82.92 % and 85.44 %, respectively. In the antibacterial activity, the nanoparticles significantly suppressed bacterial growth. The synergistic effect of nanoparticles combined with chosen broad-spectrum antibiotics showed significant inhibitory growth against the tested bacteria. Antibacterial results demonstrate outstanding inhibition against urinary tract infecting pathogens ranging from 14.42 to 22.18 mm. The synergistic effect of AgNPs and certain broad-range antibiotics on uropathogenic used in the study has shown Pseudomonas aeruginosa to have a highly inhibitory growth activity.