Extracellular biosynthesis of silver nanoparticles using cell filtrate of Streptomyces sp. ERI-3

In this study, we present a biological method for synthesis of silver nanoparticles (agnps) usingstreptomyces sp. eri-3 cell-filtrate. agn03 solution (1 mm) was added to the cell-free culture supernatant and the mixture was incubated at 28 °c for 48 h in the dark in an orbital shaker. the agnps were characterized using uv-visible spectroscopy, x-ray diffraction (xrd), transmission electron microscopy (tem) and scanning electron microscopy (sem). the nanoparticles exhibited maximum absorbance at 430 nm in uv-vis spectroscopy. the xrd spectrum exhibited 2⊖ values corresponding to the silver nanocrystals. tem and sem micrographs revealed the extracellular formation of spherical nanoparticles in the size range of 10-100 nm. agnps formed flower-like self-assembled structures after three months incubating at room temperature in the dark. the study provides the evidence that the factors in the cellfree culture supernatant facilitate synthesis of agnps. this study is the first report on the biosynthesis of agnps using supernatant of streptomyces sp. eri-3 bacterium.