Enzymatic reduction of U(VI) in groundwaters

The use of enzymatic reduction of U(VI) in remediation of groundwater conta minated with U(VI) is receiving considerable attention. Certain strains of bacteria can combine the oxidation of an organic compound to the reduction of U(VI) to U(IV), which precipitates as uraninite. In the present study, w e tested the reduction of U(VI) in groundwaters with various origins and co mpositions. In all groundwaters U(VI) was reduced by sulfate reducing bacte ria that had been activated by ethanol and trimetaphosphate. The reduction rate of U(VI) depends on sulfate concentration in water and the abundance o f bacteria in the system. This work shows that bacteria capable of U(VI) re duction are ubiquitous in nature, and suggests the possibility of a large a pplication of the enzymatic reduction of U(VI) for in situ clean up of grou ndwaters contaminated with uranium. ((C) Academie des sciences / Elsevier, Paris.).