Bioremediation of Metals Mediated by Marine Bacteria

Abstract

Metals are an intrinsic part of the earth’s crust. With rapid industrialization and urbanization, enormous amounts of industrial wastes including metal wastes are accumulating, which require special treatment. Wastes from mining and metal refining industries, sewage sludge, power plant wastes and waste incineration plants often contain substantial amounts of toxic heavy metals viz. Hg, Cd, Pb, As, Sb, Zn, Cu which pose serious treat to the environment and need to be removed from the source of pollution. Microorganisms from metal polluted habitats possess a variety of inherent mechanisms to tolerate high levels of toxic metals which include precipitation of metals as phosphate, sulphide, carbonate; volatilization via methylation/ethylation; physical exclusion in membranes and extracellular polymeric substances (EPS); energy driven metal efflux system and intracellular sequestration mediated by metallothionein like proteins. For the last several decades, metal resistant microorganisms including marine bacteria have been considered a potential alternative for heavy metal recovery and bioremediation resulting in the development and refinement of many bioremediation technologies for removal of toxic metals form contaminated soils and aqueous mining and industrial wastes/effluents. Interestingly, these bioremediation technologies are economically viable, environmental friendly and value added processes.