Genetically Modified Bacteria for Arsenic Bioremediation

Abstract

Arsenic contamination of ground water is a severe concern as consumption of same may lead to critical health hazards that include atherosclerosis, coronary heart disease, hypertension, ventricular arrhythmias, peripheral neuropathy, neurotoxicity, axonal degeneration, encephalopathy, cognitive dysfunction, hepatotoxicity, and diabetes. The conventional methods of arsenic removal such as oxidation or reduction, chemical precipitation, filtration, ion exchange, reverse osmosis, and volatilization are often insufficient and require additional steps which incur high cost. In view of the background, there is a need to develop, ecofriendly, rapid, effective process for arsenic removal from water. Biological entities such as bacteria, fungi, algae, and plants are used for bioremediation of arsenic polluted water. However, often the arsenic removal capacity of the biological agents cannot be enhanced beyond a certain limit. Hence, this chapter gives an elaborate account on several bacteria such as Agrobacterium tumefaciens , Bacillus subtilis , Bacillus idriensis , Corynebacterium glutamicum , Escherichia coli , Pseudomonas aureofaciens , Pseudomonas putida , and Sphingomonas desiccabilis , which are genetically modified for arsenic removal. Approaches using recombinant DNA technology involving genes like YCmarsM, CdglpF, ScglpF , arsM, arsR , and AtPCS , that are involved in arsenic metabolism are discussed in detail. Further, the mechanism for arsenic removal by the genetically modified microbes involving oxidation, methylation, and volatilization are also included. Eventually, the scope of developing optimized bioprocess for treatment of arsenic contaminated water is presented. Thus, recombinant bacteria have promising potential for developing future water treatment processes in order to ensure clean and safe drinking water.