Publications

Tem Investigation of U6+ and Re7+ reduction by desulfovibrio desulfiiricans, a sulfate-reducing bacterium

Xu, Huifang; Barton, Larry L.; Zhang, Pengchu Z.; Wang, Yifeng

Uranium and its fission product Tc in aerobic environment will be in the forms of UO22+ and TcO4-. Reduced forms of tetravalent U and Tc are sparingly soluble. As determined by transmission electron microscopy, the reduction of uranyl acetate by immobilized cells of Desulfovibrio desulfuricans results in the production of black uraninite nanocrystals precipitated outside the cell. Some nanocrystals are associated with outer membranes of the cell as revealed from cross sections of these metabolic active sulfate-reducing bacteria. The nanocrystals have an average diameter of 5 nm and have anhedral shape. The reduction of Re7+ by cells of Desulfovibrio desulfuricans is fast in the media containing H2 electron donor, and slow in the media containing lactic acid. It is proposed that cytochrome in these cells has an important role in the reduction of uranyl and Re7+ that is a chemical analogue for one uranium fission product Tc7+ through transferring electron from molecular hydrogen or lactic acid to the oxyions of UO22+ and ReO4-. © 2000 Materials Research Society.