@article {636, title = {Rapid Anaerobic Benzene Oxidation with a Variety of Chelated Fe(III) Forms.}, journal = {Appl Environ Microbiol}, volume = {62}, year = {1996}, month = {1996 Jan}, pages = {288-91}, abstract = {Fe(III) chelated to such compounds as EDTA, N-methyliminodiacetic acid, ethanol diglycine, humic acids, and phosphates stimulated benzene oxidation coupled to Fe(III) reduction in anaerobic sediments from a petroleum-contaminated aquifer as effectively as or more effectively than nitrilotriacetic acid did in a previously demonstrated stimulation experiment. These results indicate that many forms of chelated Fe(III) might be applicable to aquifer remediation.}, issn = {0099-2240}, author = {Lovley, D R and Woodward, J C and Chapelle, F H} } @article {640, title = {Benzene oxidation coupled to sulfate reduction.}, journal = {Appl Environ Microbiol}, volume = {61}, year = {1995}, month = {1995 Mar}, pages = {953-8}, abstract = {Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to 1 (mu)M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [(sup14)C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92\% of the added radioactivity was recovered as (sup14)CO(inf2). Molybdate, an inhibitor of sulfate reduction, inhibited benzene uptake and production of (sup14)CO(inf2) from [(sup14)C]benzene. Benzene metabolism stopped when the sediments became sulfate depleted, and benzene uptake resumed when sulfate was added again. The stoichiometry of benzene uptake and sulfate reduction was consistent with the hypothesis that sulfate was the principal electron acceptor for benzene oxidation. Isotope trapping experiments performed with [(sup14)C]benzene revealed that there was no production of such potential extracellular intermediates of benzene oxidation as phenol, benzoate, p-hydroxybenzoate, cyclohexane, catechol, and acetate. The results demonstrate that benzene can be oxidized in the absence of O(inf2), with sulfate serving as the electron acceptor, and suggest that some sulfate reducers are capable of completely oxidizing benzene to carbon dioxide without the production of extracellular intermediates. Although anaerobic benzene oxidation coupled to chelated Fe(III) has been documented previously, the study reported here provides the first example of a natural sediment compound that can serve as an electron acceptor for anaerobic benzene oxidation.}, issn = {0099-2240}, author = {Lovley, D R and Coates, J D and Woodward, J C and Phillips, E} } @article {643, title = {Stimulated anoxic biodegradation of aromatic hydrocarbons using Fe(III) ligands.}, journal = {Nature}, volume = {370}, year = {1994}, month = {1994 Jul 14}, pages = {128-31}, abstract = {Contamination of ground waters with water-soluble aromatic hydrocarbons, common components of petroleum pollution, often produces anoxic conditions under which microbial degradation of the aromatics is slow. Oxygen is often added to contaminated ground water to stimulate biodegradation, but this can be technically difficult and expensive. Insoluble Fe(III) oxides, which are generally abundant in shallow aquifers, are alternative potential oxidants, but are difficult for microorganisms to access. Here we report that adding organic ligands that bind to Fe(III) dramatically increases its bioavailability, and that in the presence of these ligands, rates of degradation of aromatic hydrocarbons in anoxic aquifer sediments are comparable to those in oxic sediments. We find that even benzene, which is notoriously refractory in the absence of oxygen, can be rapidly degraded. Our results suggest that increasing the bioavailability of Fe(III) by adding suitable ligands provides a potential alternative to oxygen addition for the bioremediation of petroleum-contaminated aquifers.}, keywords = {Benzene, Biodegradation, Environmental, Ferric Compounds, Hydrocarbons, Ligands, Methane, Nitrilotriacetic Acid, Oxidation-Reduction, Toluene, Water Pollutants, Chemical}, issn = {0028-0836}, doi = {10.1038/370128a0}, author = {Lovley, D R and Woodward, J C and Chapelle, F H} } @article {644, title = {Use of dissolved h2 concentrations to determine distribution of microbially catalyzed redox reactions in anoxic groundwater.}, journal = {Environ Sci Technol}, volume = {28}, year = {1994}, month = {1994 Jul 1}, pages = {1205-10}, issn = {0013-936X}, doi = {10.1021/es00056a005}, author = {Lovley, D R and Chapelle, F H and Woodward, J C} } @article {647, title = {Reduction of uranium by cytochrome c3 of Desulfovibrio vulgaris.}, journal = {Appl Environ Microbiol}, volume = {59}, year = {1993}, month = {1993 Nov}, pages = {3572-6}, abstract = {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.}, keywords = {Biotransformation, Chemical Precipitation, Cytochrome c Group, Desulfovibrio vulgaris, Oxidation-Reduction, Uranium, Water Pollutants, Radioactive}, issn = {0099-2240}, author = {Lovley, D R and Widman, P K and Woodward, J C and Phillips, E J} }