Biosorption of Carcinogenic Heavy Metals by Bacteria: Role and Mechanism

The various kinds of anthropogenic activities, viz., modern farming, coal burning, mining, and industries, have led to the discharge of heavy metals in the environment which besides causing disaster in the environment may also cause acute and chronic diseases in human beings. The bioaccumulation and biomagnification of heavy metals in soil and water make it a major threat to biodiversity. International Agency for Research on Cancer has classified arsenic, beryllium, cadmium, chromium, and nickel as group 1 carcinogens. The conventional physicochemical technologies used for the removal of heavy metals are cost-ineffective and sometimes generate a huge amount of toxic by-products. Bioremediation is considered as one of the safer, cleaner, cost-effective, and environmentally friendly technology for decontaminating heavy metal-contaminated sites. Microbes possess several mechanisms for metal sequestration, one of which is biosorption. This chapter will focus on the role played by bacteria in metal sequestration and various mechanisms, like binding to EPS, metallothionein, cell surface adsorption, etc., used by them for biosorption of most carcinogenic heavy metals.