Qom University of Medical Sciences Journal

Background and Objectives: Accumulation of toxic oxyanion of potassium tellurite, which has increased in the environment due to industrial activities, can cause complications in human, such as skin irritation, dermatitis, anorexia, tremor, nausea, vomiting, nervous system stimulation, convulsion, and respiratory arrest. The purpose of this research was to isolate tellurite-resistant bacteria, determine the minimum inhibitory concentration (MIC), and evaluate bioreduction of tellurite in strains.   Methods: MIC was measured by agar dilution method in 84 resistant strains isolated from wastewater. QWTm 6 strain with tolerance of tellurite concentration of 6684μg/ml was selected as superior strain. Toleration of this level of tellurite has not been reported yet.   Results: According to biochemical, phenotypic, and physiological characteristics, QWTm 6 was initially classified into Staphylococcus genus. Using the spectrophotometric technique and DDTC reagent (A 340nm & sodium diethyldithiocarbamate trihydrate), maximum elimination was seen in 0.4mM concentration of potassium tellurite in 24 hours. The strain showed high ability in the elimination of toxic oxyanion of potassium tellurite under a wide range of factors such as pH=(5-11), temperature (15-50 ◦ C), blender speed (50, 100, 150, and 200rpm), various oxyanion concentrations (0.04-1mM), and different percentages of NaCl (0-20%). This strain was also resistant to penicillin, cefixime, tetracycline, chloramphenicol, streptomycin, neomycin, erythromycin, gentamicin, kanamycin, norfloxacin, and ciprofloxacin.   Conclusion: The results of this study showed that QWTm 6 could be introduced in the international societies as an acceptable candidate for bioremediation, because of its high ability in removal and reduction of potassium tellurite.