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چکیده
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Tellurite is a rare-earth oxyanions that can be found in high concentrations in land and water near sites of waste discharge of industrial manufacturing processes. Tellurite is highly toxic to mammalian cells and microorganisms at concentrations as low as 1 µgml-1. Removal and bioreduction of tellurite (TeO3-2) by bacteria has been studied in previous works, but little is known about uptake of this oxyanion in halophilic microorganisms. In the current study, high-level tellurite-resistant moderately halophilic coccus was isolated and tellurite removal from the growth medium was determined. According to Bergeys Manual of Systematic Bacteriology and the physiological and biochemical tests formed, it was tentatively named as Salinicoccus sp. strain QW6. The quantitative determination of tellurite was done using the reagent diethyldithiocarbamate (DDTC). The influence of various concentrations of selenooxyanions (2, 4, 6, 8 and 10 mM) on tellurite removal was determined. The isolate was capable of removal tellurite in the presence of Na2SeO3 and Na2SeO4. The maximum removal of tellurite was showed in the presence of 6 mM Na2SeO3. By highering the Na2SeO3 concentration from 2 mM to 6mM, tellurite concentration in the supernatant of culture decreased to below 0.05 mM (approximately 91% of tellurite was removed) within 3 days when 0.5 mM of tellurite was added to the growth medium. At the same conditions, enhancing the Na2SeO4 concentrations from 2 to 10 mM, tellurite removal decreased and maximum removal was shown in 2 mM Na2SeO4 (approximately 62% of tellurite was removed).
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