Heavy metals play an important role in the
metabolic processes of the biota, some of them are
essential for organisms as micronutrients such as
cobalt, chromium, nickel, iron, manganese and zinc.They are involved in redox processes, to stabilize
molecules through electrostatic interactions, as
catalysts in enzymatic reactions, and regulating the
osmotic balance.Physicochemical methods have been used,
such as electrochemical treatment, ion exchange,
precipitation, reverse osmosis, evaporation, and
sorption (Congeevarama et al., 2007).Thus, bioremediation
affords a substitute to destroy or reduce the harmful
contaminants through biological activity and this
method is cost effective (Salem et al., 2012).However, at high levels, both of the
essential and non essential metals become toxic to
the organisms (Rathnayake et al., 2010).In addition,
these metals cannot be degraded to harmless
products and hence persist in the environment
indefinitely.