Microbial responses to uranium exposure and the underlying mechanisms for uranium tolerance

Uranium (U) is a naturally occurring radionuclide. The levels of U contamination in the environment as a result of accidental release from anthropogenic nuclear activities could present major health concerns for human and environmental health. The toxic effects of U are associated with its bioavailability and speciation. Prokaryotes have been present on earth for over 3 billion years and are considered to be the most successful life forms. While U is physiologically irrelevant to the microbial cells, the ever-changing environmental landscape resulting from elevated concentrations of U has facilitated the evolution of adaptive responses in bacterial strains native to uranium enriched environments. Such bacteria effectively interact with U through direct or indirect mechanisms which results in mobilization or immobilization of U in the environment. My talk will present an overview of our laboratory studies on some of these mechanisms demonstrated by the microbes isolated from the marine environment and uranium rich deposit. These uranyl-microbe interactions importantly form the basis for developing strategies for management of uranium contamination. (author)