Recent advances in the mechanism of detoxification of genotoxic and cytotoxic Cr (VI) by microbes

Chromium has different oxidation states which ranges between -2 to +6. Among all these oxidation states, Cr (VI) and Cr (III) are stable but vary in biological, geochemical and toxicological properties. Cr (VI) is more toxic than Cr (III), causes allergies, irritation and respiratory disorders. When Cr (VI) is taken up by the cell, its interaction with DNA-protein complex results in the formation of DNA-DNA cross links, and thus ultimately may cause mutagenic and carcinogenic effects. Chromium results in the formation of ROS, its interaction with DNAprotein complex and cellular components causes DNA alterations and arrests their physiological functions of the cell. ROS also may causes lipid peroxidation, DNA and protein damage and cause cancer in the cells. Chromium (VI) result in oxidative stress, genotoxicity, cytotoxicity and clastogenicity. Microbes have different mechanism of detoxification. One of the mechanisms of detoxification is Cr (VI) reduction. When Cr (VI) is reduced, forms less soluble and less toxic Cr (III), which cleans environment. Cr (VI) reduction is due to the production of chromium reductase which detoxifies Cr (VI). Chromium reductases are intrecellular, extracellular and membrane bound. Bacteria may also detoxify ROS generation by antioxidant defense mechanism. Due to above multifarious properties shown by the microbes, can be used to remediate environment from these mutagenic, carcinogenic and cytotoxic elements.