Biodegradation of Hexavalent Chromium from Paint Industry Effluent by Indigenous Bacteria

Hexavalent chromium (Cr-VI) is toxic, mutagenic and carcinogenic chemical, whereas its reduced trivalent form (Cr-III) is much less toxic. Cr-VI is widely used in paint industry, tannery industry, and so on. In the present study an attempt was made to isolate naturally occurring bacteria from paint industry effluent possessing high potentiality to reduce Cr-VI. Seven efficient chromium reducing bacterial strains were isolated as Bacillus korlensis, Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Micrococcus varians, Enterobacter intermedius and Tatumella terrea. These bacteria reduced chromium in culture media at maximum 5 mM concentration within a period of 24–72 h as determined by 1, 5-diphenylcarbazide (DPC) colorimetric method. However, significant Cr-VI reduction or biodegradation was observed at 1.25 mM substrate concentration within 24 h at 37°C. The research was very promising for development of a microbiological process to be used in the removal of toxic hexavalent chromium from the environment.