Reduction of Chromium (VI) by indigenous bacteria isolated from industrial effluents of Pakistan

The present study was aimed to isolate and examine the reduction potential of chromium resistant bacteria. For this purpose, 10 chromium resistant bacterial strains were isolated from three different samples, collected from effluents of industries. These isolated strains were designated as A, B1, B2, C, L1, L2, L3, M, I1, and I2. All strains were able to resist up to 3500 μg/ml of potassium chromate on Lagar. At optimum pH 7 and temperature 37 ℃, all isolated strains showed optimum reduction potential. The strain B1 and L3 showed 97% reduction potential in DE broth while B1 in L-broth and I2 in acetate minimal broth showed 98% and 97% reduction potential respectively. In the case of artificial sewage water, strain M and L2 showed 94% reduction potential. In sample-1 of domestic sewage water (sterile), B2 showed 94% while I2 (non-sterile) had maximum reduction potential. Sample-2 (A, C, L2, I1) from domestic sewage water (non-sterile) had 96% and A, C, L2, I1 (sterile) also showed a 96% maximum reduction potential.