Biosynthesis of silver nanoparticles using isolatedBacillus subtilis: characterization, antimicrobial activity, cytotoxicity, and their performance as antimicrobial agent for textile materials

Silver nanoparticles (AgNPs) have unique properties and a large range of applications. Biosynthesis of stable AgNPs using the extracellular filtrate ofBacillus subtiliswas proved by the characteristic surface plasmon resonance at about 420-430 nm. They were polycrystalline with spherical, hexagonal, and irregular shapes and they were negatively charged (-40 mV) with an average diameter of 20 nm. FTIR spectrum confirmed the presence of protein molecules coating AgNPs. The optimum conditions for the synthesis of tested AgNPs were 1:6 filtrate dilution, 1 mM AgNO3, pH 7, 30 degrees C , 48 h contact time under static and illuminating conditions. The synthesized AgNPs showed antibacterial activities againstEscherichia coli,Staphylococcus aureus,Pseudomonas aeruginosa,Bacillus cereus, andSalmonella typhi, antifungal activity againstCandida albicansand antiviral activity against rotavirus. Also, they showed potent cytotoxic effects on lung and hepatic carcinoma human cell lines. Meanwhile, the acute toxicity study against mice showed no significant changes in hematological, biochemical, and histological parameters of AgNPs treated mice. They also showed mild hepatoprotective effect in thioacetamide (TAA) - induced hepatic fibrosis in rats. AgNPs treated textiles fabrics showed high antimicrobial activities against different pathogenic microorganisms as well as UV protection adequacy.