HEAVY METAL RESISTANCE OF MICRORGANISMS ISOLATED FROM COAL MINING ENVIRONMENTS OF NEYVELI
Makkena Sree Lekha and Dr. V. Judia Harriet Sumathy*
â€œHeavy metalâ€ is a general collective term, which applies to the group of metals and metalloids with atomic density greater than 5 times more than water. Heavy metals are widespread pollutants of great concern as they are non-degradable. Heavy metals are highly persistent pollutants in the environment. These metals are used in various industries from which effluents are consequently discharged into the environment. Introduction of metals into the environment can produce many of microbial communities and will affect their activities. Contamination of surface sediments and natural aquatic recaptors with heavy metals is a major environmental problem all over the world. Excessive metal concentration cause threat of carcinogenesis, neuralgia, encephalopathy, respiratory cancer, and mutagenesis, cardiovascular and gastrointestinal diseases. Some of the heavy metals are essential trace elements most can be at high concentrations, toxic to all forms of life, including microbes, humans and animals. Heavy metals cannot be degraded or destroyed because they are stable and persistent as environmental contaminants. By affecting the growth, morphology and biochemical activities, heavy metals influence the Microbial population and results in decreased biomass as well as diversity. Therefore microbes have developed mechanisms to tolerate the metals either by presence of heavy metals through efflux or reduction of metal ions or to use them as terminal electron acceptors in anaerobic respiration. Most mechanism reported involves the efflux of metal ions outside the cell, and genes for tolerance mechanisms have been found on both chromosomes and plasmids. Bacteria that are resistant to and grow on metals play an important role in the biogeochemical cycling of those metal ions. The present study investigates the resistant of Zinc to microorganisms isolated from coal mining environments of Neyveli.
Keywords: Heavy Metals, Contamination, Microbial Population, Zinc and Bacteria.
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