[ frequency and antibiotic resistance of chromate tolerating microorganisms in Qom industrial wastewater]

ABSTRACT

Chromium is one of the major sources of environmental pollution and a potent occupational carcinogen. The hexavalent chromium compounds are more toxic than those of trivalent. Recent studies have suggested that reduction of Cr[VI] to its lower oxidation states and related free radical reactions play an important role in carcinogenic, genotoxic and immunotoxic effects in human and animals. This paper reports occurrence of chromium tolerant and antibiotic resistant organism of four industrial wastewaters including electroplating, textile, galvanization, and dye manufacturing in Qom. In this study 241 isolates including 23 gram positive coccus, 3 gram negative bacilli and 215 gram positive bacilli were obtained by using of LB Agar plus determined concentration of potassium chromate. A gram positive coccus, chromate reducing bacteria strain isolated from effluent of chromo plaiting could tolerate up to 760mM concentration in 34[degree]c and pH=7 within 24h and showed resistance to some antibiotics. Biochemical, physiological, morphological and 16SrRNA tests showed this bacteria belongs to staphylococcus arlettae strain R1-7A. The result indicates that the indigenous microbial isolates can be useful for hexavalent chromium detoxification of chromium contamination environment and reduction of its pathogenicity and carcinogenicity, on the other hand the control of these bacteria is important from the medical view