Purified tetra haem cytochrome c3 has been demonstrated to perform the function of U(VI) reductase in vitro, in combination with hydrogenase which is its electron donor (Lovley and Philip, 1994). In vivo studies were performed using a cytochrome c3 mutant of the close relative D. desulfuricans strain G20 and it was confirmed that cytochrome c3 plays a role in hydrogen- dependent U(VI) reduction, but suggested the existence of some additional pathways from organic electron donors to U(VI) (Payne et al., 2002). Hence, it is also evident that uranium reduction can be done by D. desulfuricans and hence the bacterium identified in soil is D. desulfuricans.