Study of Selenate- resistant Bacteria Isolated from Industrial Wastewaters

Background and Selenium is important as a key trace element which is required by most organisms in biology. Despite its importance in cellular functions, high concentrations of selenium, particularly in the forms of selenate and selenite are highly toxic. Therefore, it is necessary to perform biogeochemical studies and develop strategies for the effective control of toxic oxyanion of selenate in the environment. In this study, 30 strains were isolated from industrial wastewater in Qom Province using the enrichment culture technique and direct plating on agar. MIC of sodium selenite was measured by agar dilution method and also, antibiogram test was performed for resistant strains. Bacterial strains designated QW4 and QW184 (Qom Wastewater Number 4 and 184) exhibited very high MIC values (760 and 700, respectively) for toxic oxyanion of selenate. Conventional biochemical tests and 16S rRNA studies identified QW4 and QW184 as Proteus hauseri (FR733709-1) and Escherichia coli (AJ567606). These two bacterial strains were resistant to some antibiotics. Enrichment culture technique was found to be more useful than direct plating on agar for isolation of selenate resistant bacteria. QW4 and QW184 could be used for bioremediation of contaminated sites.