A Review on Microbial Treatments of Metal Pollution

Heavy metals like zinc, copper, nickel, mercury, cadmium, lead and chromium are the elements that have atomic masses between 63.5 and 200.6, and their specific gravity is greater than 5.0. These toxic metals are released from metal plating facilities, mining operations, fertilizer industries, tanneries, batteries, paper industries and pesticides, and directly or indirectly become part of environment. Heavy metals are non biodegradable and are carcinogenic in nature, become permanent part of food chains. Conventional treatments used for metal removal are cost effective, sludge produced is non-biodegradable and require much cost for its disposal. Microbial treatment of metal pollution is an alternative, innovative, and economically more suitable method. Microbial biomass used can be obtain naturally, from fermentation industries or can be culture on simple media. Microorganisms can mobilise heavy metals by autotrophic and heterotrophic leaching, siderophores, chelation by microbial metabolites and methylation. However, immobilisation can result from sorption to cell components or exopolymers, transport into cells and intracellular separation or precipitation as insoluble organic and inorganic compounds. Microbiological processes have significant role in determining environmental metal mobility and have actual or potential applications in bioremediation. Metallic pollution is increasing day by day and it is suggested to use microbial remediation to protect our environment from toxic effects of heavy metals