Stevia rebaudiana-mediated synthesis of silver nanoparticles: an eco-friendly approach for combating fish bacterial pathogens

BACKGROUND: Nanotechnology has generated promising strategies to formulate novel antimicrobial agents to combat pathogens. In this study, we demonstrate an environmentally friendly and low-cost fabrication of silver nanoparticles (AgNPs) using Stevia rebaudiana leaf extract as a stabilizing and reducing agent.METHODS: Aqueous extract of Stevia rebaudiana is used for the bioreduction of silver nanoparticles. The synthesized nanoparticles were characterized for their size, shape and chemical composition by UV-VIS spectrophotometer, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy, X-ray diffraction spectrophotometer (XRD) and Fourier transform infrared spectroscopy (FTIR). In addition, the antimicrobial activity of the biosynthesized AgNPs was evaluated against two fish bacterial pathogens, Aeromonas salmonicida and A. hydrophila.RESULTS: The XRD investigation confirmed the synthesis and crystallinity of AgNPs and the FTIR spectra clearly showed the interactions between the plant secondary metabolites and the produced AgNPs. The spherical structure and uniformity of AgNPs were evident from SEM analysis. Biosynthesized AgNPs showed good antibacterial activity in vitro, with the maximum activity against A. salmonicida (16.33±0.52 mm) and A. hydrophila (13.67±0.52 mm) at 80 μg/mL.CONCLUSIONS: The results illustrate the potential of Stevia rebaudiana-mediated AgNPs as a secure and reliable method for reducing Aeromonas infections in aquaculture.