Streptomyces somaliensis mediated green synthesis of silver nanoparticles

Objective(s): The development of reliable and ecofriendly process for the synthesis of nano-metals is an important aspect in the field of nanotechnology. Nano-metals are a special group of materials with broad area of applications. Materials and Methods: In this study, extracellular synthesis of silver nanoparticles (SNPs) performed by use of the gram positive soil Streptomycetes. Streptomycetes isolated from rice fields of Guilan Province, Iran (5 isolates). Initial characterization of SNPs was performed by visual color change. To determine the bacterium taxonomical identity, its colonies characterized morphologically by use of scanning electron microscope. The PCR molecular analysis of active isolate represented its identity partially. In this regard, 16S rDNA of isolate G was amplified using universal bacterial primers FD1 and RP2. The PCR products were purified and sequenced. Sequence analysis of 16S rDNA was then conducted using NCBI GenBank database using BLAST. Also SNPs were characterized by, transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD). Results: From all 5 collected Streptomyces somaliensis isolates, isolate G showed highest extracellular synthesis of SNPs via in vitro. SNPs were formed immediately by the addition of (AgNO3) solution (1 mM). UV-visible spectrophotometry for measuring surface plasmon resonance showed a single absorption peak at 450 nm, which confirmed the presence of SNPs. TEM revealed the extracellular formation of spherical silver nanoparticles in the size range of 5-35 nm. Conclusion: The biological approach for the synthesis of metal nanoparticles offers an environmentally benign alternative to the traditional chemical and physical synthesis methods. So, a simple, environmentally friendly and cost-effective method has been developed to synthesize SNPs using Streptomycetes