Mechanism of Arsenic Tolerance in Klebsiella pneumoniae (HQ857583)

Arsenic is a well-known toxic chemical and listed as a known carcinogen by the Environmental Protection Agency (EPA) and the World Health Organization (WHO, 2001). It is the 20 abundant element in the earth s crust but is widely distributed in the environment being released from both natural sources, e.g. by volcanic action, during weathering of rocks and mining as well as from anthropogenic ones, such as pesticides (e.g. calcium arsenate dimethylarsonate, disodium methylarsenate), production of paints and dyes, application of dusts from burning of fossil fuels, semiconductor industry, processing of pressure-treated wood [e.g. chromated copper arsenate (CCA)], coal combustion, high-temperature combustion and smelting of metals (Cullen and Reimer, 1989). In nature, the most common oxidation states for soluble arsenic exist as pentavalent arsenate [As(V)] and trivalent arsenite [As(III)] (Bhattacharjee and Rosen, 2007).