Actinomycetes involved in heavy metals bioremediation

Abstract

Disposal of wastes from metal excavation and processing have concentrated the heavy metals to dangerous levels in some soils and sediments. Some metals, such as calcium, cobalt, chromium copper, iron, magnesium are required nutrients and are essential. Others have no biological role (silver, aluminium, cadmium, lead, gold and mercury) and are nonessential. However these metals at higher concentrations are toxic to microorganisms. Metal contamination of soil is especially problematic because of the strong adsorption of many metals to the surfaces of soil particles. Due to the difficulty of desorbing metal contaminants, some traditional remediation methods simply immobilize metals in contaminated soils, for example, by the addition of cement or chemical fixatives, by capping with asphalt, or by in-situ vitrification. Alternatively, soils are often isolated by excavation and confinement in hazardous waste facilities. Although rapid in effect, both of these options are expensive ($30-$300/ m3) and destroy the soil’s future productivity.