The Impact of Fe(III)-reducing Bacteria on Uranium Mobility

Abstract

The ability of specialist prokaryotes to couple the oxidation of organic compounds to the reduction of Fe(III) is widespread in the subsurface. Here microbial Fe(III) reduction can have a great impact on sediment geochemistry, affecting the minerals in the subsurface, the cycling of organic compounds and the mobility of a wide range of toxic metals and radionuclides. The contamination of the environment with radioactive waste is a major concern worldwide, and this review focuses on the mechanisms by which Fe(III)-reducing bacteria can affect the solubility and mobility of one of the most common radionuclide contaminants in the subsurface, uranium. In addition to discussing how these processes underpin natural biogeochemical cycles, we also discuss how these microbial activities can be harnessed for the bioremediation of uranium-contaminated environments.

Reduction of Uranium(VI) to Uranium(IV) by Clostridia

“…Although the mechanisms of U(VI) reduction by Desulfovibrio, Geobacter, and Shewanella species are known (16,18), the mechanisms of uranium reduction by clostridia remain unclear. Our previous study showed that it is an enzymatic process, since it occurred only in the presence of growing or on May 11, 2018 by guest http://aem.asm.org/ resting cells; neither the organic acid metabolites generated, the extracellular components of the culture, nor heat-killed cells could reduce uranium anaerobically (4).…”

Particulate Phases Possibly Conveyed from Nuclear Waste Repositories by Groundwater

“…Since they are living organisms they migrate in the subsurface porous medium, being subject to a complex of biological, physical and chemical processes. Those micro-organisms act as pseudo-colloids, since their surfaces are often negatively charged, thus having the ability to bind and carry radionuclides through the subsurface environment (Johnsson et al, 2008;Luk'yanova et al, 2008;Seiler et al, 2011;Singer, Farges & Brown Jr, 2009;Wilkins et al, 2006;2010).…”

Remobilisation of uranium from contaminated freshwater sediments by bioturbation

“…Additionally, reduction of U can also occur biotically through metal-reducing bacterial metabolism in sediment (Lovley et al, 1991). This process has notably been used in recent bioremediation programs of contaminated sites where immobilisation of U in sediments was favoured by organic amendment at the sediment surface (Wall and Krumholz, 2006;Wilkins et al, 2006;Renshaw et al, 2007;Barlett et al, 2012).…”