Synthesis of anisotropic silver nanoparticles using novel strain, Bacillus flexus and its biomedical application

Synthesis of metallic nanoparticles has attracted by bacterial based production and alternative to physical and chemical approaches. The present work was focused to nominate a bacterial strain for synthesis of potential silver nanoparticles. The target was achieved by screening of 127 isolates from silver mining wastes. A strain designated S-27 found to be a potential candidate for rapid synthesis of silver nanoparticles among tested microorganisms. It was subjected to molecular characterization by 16S rDNA sequence analysis. It was found that S-27 belonging to Bacillus flexus. Synthesis of silver nanoparticles was achieved by addition of culture supernatants with aqueous silver nitrate solution, immediately it turns to brown colour solution showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles by UV-vis spectroscopy. Various instrumentation techniques, such as AFM, FESEM, XRD and FTIR, were adopted to characterize the synthesized nanoparticles. Anisotropic nanoparticles, such as spherical and triangular shaped nanoparticles, have been synthesized and sizes were found to be 12 and 65 nm, respectively. It was stable in aqueous solution in five months period of storage at room temperature in the dark. Synthesized nanoparticles showed efficacy on antibacterial property against clinically isolated multi-drug resistant (MDR) microorganisms. It is suggested that biogenic synthesis of nanoparticles have wide-application in medicine and physical chemistry and it can produce with eco-friendly, easy downstream processing and rapid scale-up processing. (c) 2012 Elsevier B.V. All rights reserved.