Comparison of Heavy Metal Resistance of Microrganisms Isolated from Coal Mining Environments of Neyveli

Heavy metals are classified into three classes : metals, heavy metals and metalloids. Metals in general are a class of chemical elements that form lustrous solids that are good conductors of heat and electricity. There are 90 naturally occurring elements, which are heavy metals, but not all of them are biologically significant. Based on their solubility under physiological conditions, 17 heavy metals may be available for living cells and are of importance for organisms and ecosystems. Among these metals, Fe, Mn are important as micronutrients. Zn, Ni, Cu, Co, Cr, W are toxic elements with high or low importance as trace elements. The metalloids exert different toxic effects than the metals because they have different chemistries. Metals are predominantly present as cationic species and metalloids are predominantly present as anionic species. Elements such as zinc and copper are essential for the normal plant growth and development since they are constituents of many enzymes and other proteins. However the concentrations of both essential and non - essential metals can result in growth inhibition and toxicity symptoms. The present study investigates and compares the resistance of Heavy metals isolated from coal mining environments of Neyveli.