ABSTRACT
The presence of heavy metals like chromium (Cr) in the soil and wastewater has become a key component of heavy metal pollution. Bioremediation, which is generally done by using microbes, can become a promising solution for the pollution caused by such transitional metals. These bioremediating microbes have the ability to change the toxic state of this metal to less toxic states. Exploiting this ability of microbes has rapidly become an emerging technology in remediation processes. Although many studies investigating the role of microbes in Cr reduction have been reported in soil and wastewater, most are limited to bioremedial strain isolation or laboratory-scale bioremediation. Advancements in molecular biology have resulted in molecular interventions to be considered as a next step in environmental and bioremedial studies. Various studies are now underway to decipher the molecules and mechanisms behind the ability of microbes to process the toxic Cr(VI) form of the metal and convert it to a more stable Cr(III) state. Genetics and omics approaches have looked into mechanisms of efflux pumps, reactive oxygen species (ROS), oxidation molecules, and reductases, among others. This chapter introduces chromium and the risks associated with its pollution, and discusses various bioremediation studies in soil and water as well as the attempts to understand molecular mechanisms of the bioremediation of chromium.
