EFFECT OF CADMIUM AND ZINC HEAVY METALS ON THE SOIL BACTERIA ISOLATED FROM COAL MINE REGION

Abstract

Study of growth pattern of isolated soil bacteria from Raniganj coal mine area shows an unusual increase in growth rate of the isolated bacteria when treated with heavy metal stress in the culture media. The metals used were Cadmium (Cd) and Zinc (Zn). Utilization of metal ions by the bacterial cells was studied by detection of leftover metal in the culture medium after optimal growth, by Dithizone method and surface adsorption of metal ions on bacterial cell by FTIR technique. The amount of total thiol and non-protein thiol of the bacterial culture was assayed for the presence of thiol containing protein like Metallothionein. Metallothionein production was also studied using SDS-PAGE and Western blot technique to find if the cells were stressed in the presence of increasing concentration of Zn2+ and Cd2+. Metallothioneins (MTs) are proteins rich in cysteine residues having low molecular weight. They perform different functions like scavenging of free radicals, involvement in maintaining metal balance, regulation of metabolic activities and protective role against damage caused by heavy metals. Metallothioneins can be correlated with heavy metal contamination of an environment and thus may be considered as bio-marker for environmental pollution.