Antibacterial activity of biosynthesized selenium nanoparticles from soils borne-bacteria under electric and non-electric field conditions

Nanotechnology enables the engineering of materials with unique physicochemical properties at the nanoscale. This study aimed to biosynthesize selenium nanoparticles (SeNPs) using the soil-borne bacterium Ralstonia mannitolilytica and sodium selenite (Na₂SeO₃), and to evaluate their antibacterial activity against six bacterial pathogens with and without an externally applied electric field. The SeNPs were characterized by UV–Vis spectroscopy, TEM, EDS, XRD, AFM, and zeta potential analysis. UV–Vis showed a characteristic absorption peak at 236 nm, while TEM revealed predominantly spherical nanoparticles with a mean diameter of approximately 34 nm. The zeta potential was −22.47 mV. Antibacterial activity was evaluated at 4–64 µg/mL using the agar well diffusion assay. The highest inhibition was observed at 64 µg/mL. Application of a 6.25 kV/m electric field significantly enhanced antibacterial activity (p < 0.001), with inhibition zones exceeding 13 mm for five species. These findings demonstrate enhanced broad-spectrum antibacterial activity of biosynthesized SeNPs under electric-field conditions.