BIOLOGICAL REMOVAL OF LEAD BY BACILLUS SP. OBTAINED FROM METAL CONTAMINATED INDUSTRIAL AREA

Abstract

In the present study bacterial strains were isolated from soil, sediment and water samples of metal polluted environment. As a result, various 164 heterotrophic bacterial strains were isolated and studied the multiple metal tolerance profile and lead bioaccumulation potentiality. We also analyze the metal contamination of the selected study area. The average abundance order of heavy metal contents in soil, water and sediments were Zn>Cu>Pb>Cd. Zinc concentration ranged from 39.832µg/L to 310.24µg/L in water, 12.81µg/g to 407.53µg/g in soil and 81.06µg/g to 829.54µg/g in sediment; copper concentration from 25.54µg/L to 66.29µg/L in water, 8.22µg/g to 73.11µg/g in soil and 32.28µg/g to 600.61µg/g in sediment; lead concentration from 8.09µg/L to 25.23µg/L in water, 5.31µg/g to 73.11µg/g in soil and 1.02µg/g to 60.14µg/g in sediment and cadmium concentration ranged from 39.832µg/L to 310.24µg/L in water, 12.81µg/g to 407.53µg/g in soil and 81.06µg/g to 829.54µg/g in sediment. Metal resistance studies of the bacterial isolates revealed that out of 164 isolates collected about 45% of the isolates showed very high tolerance (>6000µg/ml) to lead. Tolerance to Cd and Zn were relatively low (<500 µg/ml). Resistance to Ni and Cr were in between 1000µg/ml - 1500µg/ml. A total of 18 bacterial genera were recorded from the study area; ten genera from soil and 11 from water, while only 5 bacterial genera were recorded from sediment samples. Bioaccumulation studies revealed that with increase in time, the biomass of the selected bacterial isolates increased. Correspondingly, with increase in biomass, the heavy metal bioaccumulation was also increased. In lead removal studies, around 50% of the lead in the experimental flasks was reduced by Bacillus sp. In control flask, only 5% metal reduction occurs. The obtained results showed that the selected Bacillus sp. is good bioaccumulation medium for lead ions.