Hexavalent chromium bioremediation with insight into molecular aspect: an overview

Hexavalent chromium among the chromium containing compounds is the most harmful and potentially toxic, imparts severe hazard to humans besides plants, including the entire environment. There have been found many bacterial, algal, fungal and plant species that can thrive and grow under this Cr (VI) stress. These organisms have evolved to employ different strategies to reduce the effects of Cr (VI) toxicity. Generally, strategies like biosorption, biotransformation, use of various enzymes like chromate reductase, uptake and metabolize Cr (VI) through membrane transport, conversion of Cr (VI) to Cr (III), a potentially non-toxic state and discharging these metals from the cells into the surrounding environment after reduction are applied to detoxify the effects produced by Cr (VI). Therefore, this review article focuses on the various bioremediation procedures adopted by different organisms with a view into the molecular aspects and the genetic background manipulation behind these bioremediation strategies.