| Summary: | Background and Objectives: Heavy metals causing the pollution of environment through industrial activities. biological methods have been used to remove toxic element that compared to other methods are promising technologies with higher efficiency and lower cost. The aim of this study was to isolate strains with high tolerance to arsenic from 3 area of groundwater Sirjan. Materials and methods: were cultured on LB agar medium containing 5ppm arsenic. After 24h incubation, 25 colonies of resistant strains were isolated. DNA was extracted by using phenol chloroform method and contaminated samples were examined by PCR reaction. In order to detect microorganisms by molecular methods , 16SrDNA primers were used. Amount of growth was determined by spectrophotometry at 600 nm in 24h. Antimicrobial resistance patterns and biosorption analysis was performed by method of antibiogram and atomic absorption spectroscopy. The strain was identified by 16SrDNA PCR sequencing. Results and Conclusion: From 100% of bacterial isolates in this study were 20% gram positive, 40% gram negative bacilli, 28% gram positive cocci and12% Gram negative spiral. Genetic analysis results for the basil sample showed that the strain was 100% consistent with the Bacillus Cereus strain LS24. The dominant strain had a minimum inhibitory concentration just 1000 ppm at a temperature of 40°C, pH 7 and 150 rpm. This bacterium was removed 62.8% of arsenic from the solution. Superior strain was Bacillus cereus LS24 by biochemical and genetic methods.
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