Abstract

Bacterial strains (CrT-11, CrT-12, Bravibacterium sp. CrT-13, CrT-14) were isolated from the effluents of tanneries. All strains could resist very high concentration of K₂CrO₄ that is up to 40 mg ml^-1 on nutrient agar and 25 mg ml^-1 in nutrient broth. They have wide pH (5 to 9) and temperature (24 to 42ËšC) growth range. They exhibited multiple metals (Ni, Zn, Mn, Cu, Co, Pb) and antibiotics (streptomycin, ampicillin, tetracycline, kanamycin, chloramphenicol) resistances. All the strains were able to reduce Cr (VI) in to Cr (III) aerobically. Bravibacterium sp. CrT-13 accumulates and reduce more Cr (VI) at all the concentrations applied in comparison to the other strains. These bacterial strains also take up and reduce Cr (VI) present in industrial effluents, and their reduction potential was not significantly affected in the presence of different metallic salts.

Key words: Cr (VI) reduction, bacteria, industrial effluent, heavy metals.