Final Technical Report
- University of Missouri-Columbia
Bioremediation of radionuclides and metals in the subsurface necessitate an understanding of the metabolic capacities and interactions of the anaerobic microorganisms that are found there, including members of the sulfate-reducing bacteria (SRB). Genetic investigation into the pathway of reductant flow to U(VI) in the SRB belonging to the genus Desulfovibrio has been the focus of this project. In Dv. desulfuricans strain G20, we confirmed the importance of the tetraheme cytochrome c3 by disruption of the gene encoding that cytochrome, cycA, and demonstrated a decrease in the ability of the mutant (I2) to reduce U(VI). We found that the cytochrome c3 was necessary for electrons from pyruvate to reach sulfate or fumarate as terminal electron acceptors. It was not needed for electrons from lactate to reach sulfate, from which we infer that a different pathway is used for the electrons from these two substrates. Cyrstal structure of the tetraheme cytochrome c3 was obtained and site-directed mutations of the protein indicated a binding site for metals at heme 4 of the structure. Kinetic studies for oxidation of reduced cytochrome c3 with U(VI) or molybdate revealed a preference for U(VI) as a substrate. Evidence for a role for sodium gradients in the energetic scheme for this soil organism was obtained.
- Research Organization:
- Curators of the University of Missouri-Columbia
- Sponsoring Organization:
- USDOE Office of Energy Research (ER)
- DOE Contract Number:
- FG02-97ER62495
- OSTI ID:
- 948467
- Report Number(s):
- DOE/ER/62495-Final
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BINDING ENERGY
BIOREMEDIATION
Bioremediation
CYTOCHROMES
DESULFOVIBRIO
ELECTRONS
GENES
GENETICS
HEME
KINETICS
LACTATES
MICROORGANISMS
MOLYBDATES
MUTANTS
MUTATIONS
OXIDATION
PROTEINS
RADIOISOTOPES
SODIUM
SOILS
STRAINS
SUBSTRATES
SULFATE-REDUCING BACTERIA
SULFATES
Uranium reduction
VALENCE
bacterial mutants
c-type cytochromes
sulfate-reducing bacteria