Background and Aim:The use of biologically derived metal nanoparticles for antimicrobial purposes is going to be an issue of considerable importance. Living organisms especially bacteria which are easy to grow and culture can be tested for biological synthesis of these nanoparticles. The aim of this study is production of selenium nanoparticle by indigenous bacterial isolates and its further characterization. Bacterium G7 which has been isolated in this study from a glass factory sewage was able to synthesize selenium nanoparticle with diameter of 31-500nm. Methods:Bacteria were isolated and purified by addition of galas factory sewage samples into nutrient medium supplemented with correct amount of metal salt (100 mg/lit) incubated on a rotary shaker (150 rpm) at 30 °C. Colony morphology and gram staining of bacterial isolates were determined. Selenium nanoparticles were extracted from pure culture of screened bacterium using centrifugation, repeated washing process and disrupting cells by liquid nitrogen. Disrupted cells were resuspended in Tris HCl buffer and washed in chloroform and ethanol after centrfugation. Finally resuspended cleaned nanoparticles were preserved in deionized water and analyzed with Dynamic light scattering (DLS). Results:The appearance of red color in the culture plate suggested the formation of selenium nanoparticles. The biosynthesized selenium nanoparticle were with the size range of 31nm to 500nm with an average size of 245nm.Isolated bacterium has coccus form and gram negative.

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