Reduction of uranium by cytochrome c3 of Desulfovibrio vulgaris.

TitleReduction of uranium by cytochrome c3 of Desulfovibrio vulgaris.
Publication TypeJournal Article
Year of Publication1993
AuthorsLovley DR, Widman PK, Woodward JC, Phillips EJ
JournalAppl Environ Microbiol
Date Published1993 Nov
KeywordsBiotransformation, Chemical Precipitation, Cytochrome c Group, Desulfovibrio vulgaris, Oxidation-Reduction, Uranium, Water Pollutants, Radioactive

The mechanism for U(VI) reduction by Desulfovibrio vulgaris (Hildenborough) was investigated. The H2-dependent U(VI) reductase activity in the soluble fraction of the cells was lost when the soluble fraction was passed over a cationic exchange column which extracted cytochrome c3. Addition of cytochrome c3 back to the soluble fraction that had been passed over the cationic exchange column restored the U(VI)-reducing capacity. Reduced cytochrome c3 was oxidized by U(VI), as was a c-type cytochrome(s) in whole-cell suspensions. When cytochrome c3 was combined with hydrogenase, its physiological electron donor, U(VI) was reduced in the presence of H2. Hydrogenase alone could not reduce U(VI). Rapid U(VI) reduction was followed by a subsequent slow precipitation of the U(IV) mineral uraninite. Cytochrome c3 reduced U(VI) in a uranium-contaminated surface water and groundwater. Cytochrome c3 provides the first enzyme model for the reduction and biomineralization of uranium in sedimentary environments. Furthermore, the finding that cytochrome c3 can catalyze the reductive precipitation of uranium may aid in the development of fixed-enzyme reactors and/or organisms with enhanced U(VI)-reducing capacity for the bioremediation of uranium-contaminated waters and waste streams.

Alternate JournalAppl. Environ. Microbiol.
PubMed ID8285665