Chromate tolerant bacteria isolated from tannery effluent

Abstract The occurrence of metal tolerant and antibiotic resistant organisms was investigated in tannery effluent. Seventy-seven isolates comprising heterotrophs (41) and coliforms (36) which were tolerant to chromate level of > 50 μg / ml were selected for detailed study. The majority of the coliforms were resistant to higher levels of chromate (200 μg/ml) whereas around 3% of the heterotrophs were resistant to Cr 6+ at a level of > 150 μg / ml . All chromate tolerant heterotrophs were also tolerant to Cu 2+ (100%) whereas only 58.53% coliforms were tolerant to Cu 2+ . Except in the case of Cd 2+ a higher number of heterotrophs were found tolerant to other heavy metals tested. Both groups of isolates were found sensitive to mercury. Resistance to cephaloridine was more abundant ( P P 2+ were also resistant to polymixin-B.