Isolation and Characterization of Arsenic Reducing Bacteria from Industrial Effluents and their Potential Use in Bioremediation of Wastewater

The present study is aimed at assessing the ability of Klebsiella oxytoca, Citrobacter freundii and Bacillus anthracis to reduce arsenate into arsenite. C. freundii and B. anthracis could tolerate As (V) up to 290 mg/l. K. oxytoca resisted As up to 240 mg/l. K. oxytoca and B. anthracis showed optimum growth at pH 7 while C. freundii showed maximum growth at pH 5. C. freundii and B. anthracis showed optimum growth at 37 degrees C while the maximum growth of K. oxytoca was observed at 30 degrees C. K. oxytoca and B. anthracis were found sensitive against ampicillin while C. freundii showed resistance against it. C. freundii and B. anthracis were sensitive to erythromycin, kanamycine, nalidixic acid, and tetracycline while K. oxytoca was found resistant against these antibiotics. All bacterial strains were found to be sensitive to amoxicillin, chloramphenicol, neomycine, oxytetracycline, streptomycine, and polymixin B but all bacterial strains showed resistance against bacitracin. In arsC reductase crude assay K. oxytoca, C. freundii and B. anthracis showed high ability to reduce As(V) into As(III) 78%, 70%, and 84%, respectively. The bacterial isolates can be exploited for bioremediation of arsenic containing wastes, since they seem to have the potential to reduce the arsenate into arsenite form.