Biogenic Synthesis and Potential Applications of Nano-Ag Particles from Bacillus velezensis KKWHNGU1 Isolated from Photovoltaic Solar Panel

Bacteria on photovoltaic (PV) solar panels have adapted to dehydration, temperature fluctuations, and sunlight. In the current study, a bacterial strain, Bacillus velezensis KKWHNGU1, was isolated from a photovoltaic solar panel and characterized. The strain demonstrated resistance to acidic pH (pH 5), salt (1–9% w/v), UV radiation (approximately 8 min), and temperatures of up to 55 °C. Silver nanoparticles (AgNPs) were synthesized using this strain via a green synthesis approach. Tandem mass spectrometry with liquid chromatography (LC–MS) was used to perform metabolomics, which detected substances such as 2-Hydroxy-3-methylhexadecanoyl CoA, Lapachol, Oxytocin, Icosanoyl-CoA, 3-hydroxyisoheptadecanoyl-CoA, etc. in ethyl acetate extracts. AgNPs synthesis was confirmed by UV–visible spectroscopy, which showed wavelength peaks around 430 and 492 nm, and functional groups were identified based on FTIR. XRD analysis revealed three high-intensity peaks at 27.9°, 32.2°, and 46.3°, demonstrating the crystalline form of AgNPs. According to Scanning electron microscopy (SEM), the AgNPs were spherical and had a regular size of 87 nm, whereas EDX examination confirmed that the produced AgNPs contained 84.10 wt.% Ag. Antimicrobial activity testing demonstrated maximum efficacy against Staphylococcus aureus (12 mm zone of inhibition), followed by Serratia marcescens, Priestia megaterium (9 mm each), and Escherichia coli (8 mm) at a concentration of 1 mg. The AgNPs also exhibited antibiotic removal capabilities, with a maximum cephalexin removal efficiency of 80.85% at a 10 ppm concentration over a contact time of 100 min. The removal efficiency decreased at higher concentrations (57.69% at 30 ppm and 12.97% at 50 ppm). These findings suggest potential applications of the synthesized AgNPs in water treatment and biomedical fields.