A REVIEW ON BIOREMEDIATION OF HEAVY METALS BY MICROBES

Over the last few years due to the rapid industrialisation everywhere throughout the world to fulfil the demands of growing population dissemination and mobilization of the poisonous heavy metals in the environment has been expanded to a destructive level .These heavy metals when enter in the food chain show fatal effect on human wellness when present at a slightly higher concentration than that required for regular metabolic process. Contamination caused due to the presence of these toxic heavy metals has become a global issue these days in spite of the fact that the seriousness and contamination level contrast place to place .Therefore the need of safe and effective techniques to eliminate these heavy metals is the requirement of sustainable living. Unlike the organic compounds that degenerate naturally , heavy metals do not break down themselves and therefore get assembled at various important sites. With the increasing awareness for the protection of environment emphasis is more on the development of eco friendly techniques for the decontamination procedures. Bioremediation implies cleanup of the contaminated environment by transforming harmful heavy metals into less harmful form by microorganisms or its enzymes . Hence bioremediation can be described as the ‘green basic technique for the expulsion of heavy metal without creating auxiliary metabolites in the environment. Utilization of microbial frameworks for the biological degradation of heavy metals is most preferred on account of its low expenses and minimum waste producing techniques. Despite of the increasing concentration of these harmful heavy metals microorganisms have adopted a variety mechanisms to adjust themselves to these poisonous heavy metals like lead ,mercury, Zinc ,nickel etc leading to the immobilization, removal or detoxification of these heavy metals. The present paper specifically focuses on the sources of heavy metals , their poisonous consequences on human health and recent studies made on the bioremediation of these deadly heavy metals using microbes. It also highlights the microbial techniques for the degradation of these deadly heavy metals at a rapid rate from the environment as well as future possibilities and limitations of bioremediation.