Abstract
For biosafety purposes, the genotoxicity of biosynthesized silver nanoparticles (Ag-NPs) was assessed using comet assay for the first time on Blood Lymphocytes, with zero tail migration and 100% head intensity indicating non-genotoxic effect. Ag-NPs have been projected as a new generation of antimicrobial agents because of its antimicrobial property. Ag-NPs were biomediated by Egyptian Streptomyces roseolus for the first time, that was molecularly identified using 16S rRNA sequencing under accession no. MT071505. Biosynthesized Ag-NPs were characterized using UV-Vis spectroscopy, XRD, TEM, FTIR, and DLS. FTIR confirmed the presence of different bioactive functional groups, such as, O-H, N-H, C-H, C-O-C, C-NH2, and C=O acting as reducing-stabilizing agents for biosynthesized Ag-NPs. Biosynthesized Ag-NPs exhibited antimicrobial activity against some multi-drug resistant Gram-positive and Gram-negative pathogens. MBC of biosynthesized Ag-NPs against Listeria monocytogenes and Klebsiella pneumonia were 0.195 and 0.048 mg/mL, respectively, with tolerance level of 2 confirming its biocidal effect. SEM imaging of Ag-NPs-treated L. monocytogenes and K. pneumonia showed shrunk destroyed cells after 6h. Biosynthesized Ag-NPs exhibited IC50 of <0.3 and 8.21 mg/mL, respectively, on normal Human Skin Fibroblast, and Blood Lymphocytes. IC50 values were significantly higher than its MBC values, with no harmful cytotoxic-effect, thus can be safely applied at its biocidal concentration. An ecofriendly biomediated synthesis of Ag-NPs was described with easy scale-up, non-toxic by-products, so, it can be recommended as powerful-safe antimicrobial agent.