Microbial Tolerance Strategies Against Cadmium Toxicity

Cadmium (Cd) is a heavy metal found in the environment because it is released from natural and anthropogenic sources. Cd is a persistent, nonbiodegradable pollutant with great toxicity for plants, animals, and microorganisms. Although Cd toxicity, some microorganisms can inhabit different environments contaminated with toxic levels of Cd2+ because they have developed Cd tolerance and detoxification mechanisms. These mechanisms include the production of extracellular chelating compounds, the adsorption of Cd2+ in the cellular surface, the transport of Cd2+ from the cytoplasm using efflux pumps, and Cd intracellular complexation with glutathione, metallothionein, and phytochelatins. This chapter shows the state-of-the-art of Cd-tolerant microorganisms and describes the main mechanisms employed in Cd tolerance by bacteria and fungi.