ABSTRACT
Previous in vitro experiments with Desulfovibrio vulgaris strain Hildenborough demonstrated that extracts containing hydrogenase and cytochrome c
3 could reduce uranium(VI) to uranium(IV) with hydrogen as the electron donor. To test the involvement of these proteins in vivo, a cytochrome c
3 mutant of D. desulfuricans strain G20 was assayed and found to be able to reduce U(VI) with lactate or pyruvate as the electron donor at rates about one-half of those of the wild type. With electrons from hydrogen, the rate was more severely impaired. Cytochrome c
3 appears to be a part of the in vivo electron pathway to U(VI), but additional pathways from organic donors can apparently bypass this protein.
Neptunium and Uranium Reduction Chemistry-A
