In industrialized areas, high concentrations of heavy metals have been often found in effluent, soils and wastes, establishing a serious ecological risk. Microorganisms are the first biota that undergoes direct and indirect impacts of heavy metals. The present study was conducted to isolate the heavy metal resistant bacteria from metal rich soil from lignite mining site to assess its capacity to remove heavy metals. Five different bacterial strains were isolated and designated as HMB1, HMB2, HMB3, HMB4 and HMB5 and they were tested against different concentrations of heavy metals viz., Hg, Cr and Ni. Three different methods such as living cells, dead cells and immobilization techniques were used for assessment of capacity of all the five strains to remove metals from the solution containing 100 mg/L. The results of the present study indicated that the maximum heavy metal removal was found to be high in immobilization technique followed by dead cells and living cells. Among the five strains, the HMB2 was high efficient than the others strains in all the methods. Based on the morphological and biochemical characterization the strains were identified. The bacterial strain HMB1 was belonged to Bacillus sp., the strain HMB2 was belonged to Bacillus subtilis, the strains HMB3 and HMB4 were belonged to Pseudomonas sp. and the strain HMB5 was belonged to Serratia sp. This indicated that the potential use of these bacterial isolates for removal of heavy metals from wastewater and industrial effluents containing higher concentration of heavy metals.
