@article {488,
	title = {Gene transcript analysis of assimilatory iron limitation in Geobacteraceae during groundwater bioremediation.},
	journal = {Environ Microbiol},
	volume = {10},
	year = {2008},
	month = {2008 May},
	pages = {1218-30},
	abstract = {Limitations on the availability of Fe(III) as an electron acceptor are thought to play an important role in restricting the growth and activity of Geobacter species during bioremediation of contaminated subsurface environments, but the possibility that these organisms might also be limited in the subsurface by the availability of iron for assimilatory purposes was not previously considered because copious quantities of Fe(II) are produced as the result of Fe(III) reduction. Analysis of multiple Geobacteraceae genomes revealed the presence of a three-gene cluster consisting of homologues of two iron-dependent regulators, fur and dtxR (ideR), separated by a homologue of feoB, which encodes an Fe(II) uptake protein. This cluster appears to be conserved among members of the Geobacteraceae and was detected in several environments. Expression of the fur-feoB-ideR cluster decreased as Fe(II) concentrations increased in chemostat cultures. The number of Geobacteraceae feoB transcripts in groundwater samples from a site undergoing in situ uranium bioremediation was relatively high until the concentration of dissolved Fe(II) increased near the end of the field experiment. These results suggest that, because much of the Fe(II) is sequestered in solid phases, Geobacter species, which have a high requirement for iron for iron-sulfur proteins, may be limited by the amount of iron available for assimilatory purposes. These results demonstrate the ability of transcript analysis to reveal previously unsuspected aspects of the in situ physiology of microorganisms in subsurface environments.},
	keywords = {Bacterial Proteins, Biodegradation, Environmental, Culture Media, Ferric Compounds, Ferrous Compounds, Fresh Water, Gene Expression Regulation, Bacterial, Geobacter, Iron, Multigene Family, Phylogeny, Polymerase Chain Reaction, Repressor Proteins, Reverse Transcriptase Polymerase Chain Reaction, Transcription, Genetic, Uranium, Water Pollution, Radioactive},
	issn = {1462-2920},
	doi = {10.1111/j.1462-2920.2007.01537.x},
	author = {O{\textquoteright}Neil, Regina A and Holmes, Dawn E and Coppi, Maddalena V and Adams, Lorrie A and Larrahondo, M Juliana and Ward, Joy E and Nevin, Kelly P and Woodard, Trevor L and Vrionis, Helen A and N{\textquoteright}guessan, Lucie A and Lovley, Derek R}
}
@article {493,
	title = {Subsurface clade of Geobacteraceae that predominates in a diversity of Fe(III)-reducing subsurface environments.},
	journal = {ISME J},
	volume = {1},
	year = {2007},
	month = {2007 Dec},
	pages = {663-77},
	abstract = {There are distinct differences in the physiology of Geobacter species available in pure culture. Therefore, to understand the ecology of Geobacter species in subsurface environments, it is important to know which species predominate. Clone libraries were assembled with 16S rRNA genes and transcripts amplified from three subsurface environments in which Geobacter species are known to be important members of the microbial community: (1) a uranium-contaminated aquifer located in Rifle, CO, USA undergoing in situ bioremediation; (2) an acetate-impacted aquifer that serves as an analog for the long-term acetate amendments proposed for in situ uranium bioremediation and (3) a petroleum-contaminated aquifer in which Geobacter species play a role in the oxidation of aromatic hydrocarbons coupled with the reduction of Fe(III). The majority of Geobacteraceae 16S rRNA sequences found in these environments clustered in a phylogenetically coherent subsurface clade, which also contains a number of Geobacter species isolated from subsurface environments. Concatamers constructed with 43 Geobacter genes amplified from these sites also clustered within this subsurface clade. 16S rRNA transcript and gene sequences in the sediments and groundwater at the Rifle site were highly similar, suggesting that sampling groundwater via monitoring wells can recover the most active Geobacter species. These results suggest that further study of Geobacter species in the subsurface clade is necessary to accurately model the behavior of Geobacter species during subsurface bioremediation of metal and organic contaminants.},
	keywords = {Biodegradation, Environmental, Ecosystem, Ferric Compounds, Geobacter, Hydrocarbons, Aromatic, Molecular Sequence Data, Oxidation-Reduction, Petroleum, Phylogeny, Polymerase Chain Reaction, RNA, Ribosomal, 16S, Sequence Analysis, DNA, Uranium},
	issn = {1751-7362},
	doi = {10.1038/ismej.2007.85},
	author = {Holmes, Dawn E and O{\textquoteright}Neil, Regina A and Vrionis, Helen A and N{\textquoteright}guessan, Lucie A and Ortiz-Bernad, Irene and Larrahondo, Maria J and Adams, Lorrie A and Ward, Joy A and Nicoll, Julie S and Nevin, Kelly P and Chavan, Milind A and Johnson, Jessica P and Long, Philip E and Lovley, Derek R}
}
@article {526,
	title = {Microbial incorporation of 13C-labeled acetate at the field scale: detection of microbes responsible for reduction of U(VI).},
	journal = {Environ Sci Technol},
	volume = {39},
	year = {2005},
	month = {2005 Dec 1},
	pages = {9039-48},
	abstract = {A field-scale acetate amendment experiment was performed in a contaminated aquifer at Old Rifle, CO to stimulate in situ microbial reduction of U(VI) in groundwater. To evaluate the microorganisms responsible for microbial uranium reduction during the experiment, 13C-labeled acetate was introduced into well bores via bio-traps containing porous activated carbon beads (Bio-Sep). Incorporation of the 13C from labeled acetate into cellular DNA and phospholipid fatty acid (PLFA) biomarkers was analyzed in parallel with geochemical parameters. An enrichment of active sigma-proteobacteria was demonstrated in downgradient monitoring wells: Geobacter dominated in wells closer to the acetate injection gallery, while various sulfate reducers were prominent in different downgradient wells. These results were consistent with the geochemical evidence of Fe(III), U(VI), and SO(4)2- reduction. PLFA profiling of bio-traps suspended in the monitoring wells also showed the incorporation of 13C into bacterial cellular lipids. Community composition of downgradient monitoring wells based on quinone and PLFA profiling was in general agreement with the 13C-DNA result. The direct application of 13C label to biosystems, coupled with DNA and PLFA analysis,},
	keywords = {Acetates, Biodegradation, Environmental, Carbon Isotopes, Electrophoresis, Polyacrylamide Gel, Geobacter, Phylogeny, Polymerase Chain Reaction, Proteobacteria, Uranium},
	issn = {0013-936X},
	author = {Chang, Yun-Juan and Long, Philip E and Geyer, Roland and Peacock, Aaron D and Resch, Charles T and Sublette, Kerry and Pfiffner, Susan and Smithgall, Amanda and Anderson, Robert T and Vrionis, Helen A and Stephen, John R and Dayvault, Richard and Ortiz-Bernad, Irene and Lovley, Derek R and White, David C}
}
@article {530,
	title = {Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site.},
	journal = {Appl Environ Microbiol},
	volume = {71},
	year = {2005},
	month = {2005 Oct},
	pages = {6308-18},
	abstract = {The geochemistry and microbiology of a uranium-contaminated subsurface environment that had undergone two seasons of acetate addition to stimulate microbial U(VI) reduction was examined. There were distinct horizontal and vertical geochemical gradients that could be attributed in large part to the manner in which acetate was distributed in the aquifer, with more reduction of Fe(III) and sulfate occurring at greater depths and closer to the point of acetate injection. Clone libraries of 16S rRNA genes derived from sediments and groundwater indicated an enrichment of sulfate-reducing bacteria in the order Desulfobacterales in sediment and groundwater samples. These samples were collected nearest the injection gallery where microbially reducible Fe(III) oxides were highly depleted, groundwater sulfate concentrations were low, and increases in acid volatile sulfide were observed in the sediment. Further down-gradient, metal-reducing conditions were present as indicated by intermediate Fe(II)/Fe(total) ratios, lower acid volatile sulfide values, and increased abundance of 16S rRNA gene sequences belonging to the dissimilatory Fe(III)- and U(VI)-reducing family Geobacteraceae. Maximal Fe(III) and U(VI) reduction correlated with maximal recovery of Geobacteraceae 16S rRNA gene sequences in both groundwater and sediment; however, the sites at which these maxima occurred were spatially separated within the aquifer. The substantial microbial and geochemical heterogeneity at this site demonstrates that attempts should be made to deliver acetate in a more uniform manner and that closely spaced sampling intervals, horizontally and vertically, in both sediment and groundwater are necessary in order to obtain a more in-depth understanding of microbial processes and the relative contribution of attached and planktonic populations to in situ uranium bioremediation.},
	keywords = {Acetates, Biodegradation, Environmental, Deltaproteobacteria, DNA, Bacterial, DNA, Ribosomal, Ferric Compounds, Fresh Water, Geologic Sediments, Phylogeny, Polymerase Chain Reaction, RNA, Ribosomal, 16S, Sulfates, Uranium, Water Pollution},
	issn = {0099-2240},
	doi = {10.1128/AEM.71.10.6308-6318.2005},
	author = {Vrionis, Helen A and Anderson, Robert T and Ortiz-Bernad, Irene and O{\textquoteright}Neill, Kathleen R and Resch, Charles T and Peacock, Aaron D and Dayvault, Richard and White, David C and Long, Philip E and Lovley, Derek R}
}
@article {542,
	title = {Resistance of solid-phase U(VI) to microbial reduction during in situ bioremediation of uranium-contaminated groundwater.},
	journal = {Appl Environ Microbiol},
	volume = {70},
	year = {2004},
	month = {2004 Dec},
	pages = {7558-60},
	abstract = {Speciation of solid-phase uranium in uranium-contaminated subsurface sediments undergoing uranium bioremediation demonstrated that although microbial reduction of soluble U(VI) readily immobilized uranium as U(IV), a substantial portion of the U(VI) in the aquifer was strongly associated with the sediments and was not microbially reducible. These results have important implications for in situ uranium bioremediation strategies.},
	keywords = {Acetates, Biodegradation, Environmental, Deltaproteobacteria, Fresh Water, Geologic Sediments, Oxidation-Reduction, Solubility, Uranium, Water Pollutants, Radioactive},
	issn = {0099-2240},
	doi = {10.1128/AEM.70.12.7558-7560.2004},
	author = {Ortiz-Bernad, Irene and Anderson, Robert T and Vrionis, Helen A and Lovley, Derek R}
}
@article {553,
	title = {Vanadium respiration by Geobacter metallireducens: novel strategy for in situ removal of vanadium from groundwater.},
	journal = {Appl Environ Microbiol},
	volume = {70},
	year = {2004},
	month = {2004 May},
	pages = {3091-5},
	abstract = {Vanadium can be an important contaminant in groundwaters impacted by mining activities. In order to determine if microorganisms of the Geobacteraceae, the predominant dissimilatory metal reducers in many subsurface environments, were capable of reducing vanadium(V), Geobacter metallireducens was inoculated into a medium in which acetate was the electron donor and vanadium(V) was the sole electron acceptor. Reduction of vanadium(V) resulted in the production of vanadium(IV), which subsequently precipitated. Reduction of vanadium(V) was associated with cell growth with a generation time of 15 h. No vanadium(V) was reduced and no precipitate was formed in heat-killed or abiotic controls. Acetate was the most effective of all the electron donors evaluated. When acetate was injected into the subsurface to enhance the growth and activity of Geobacteraceae in an aquifer contaminated with uranium and vanadium, vanadium was removed from the groundwater even more effectively than uranium. These studies demonstrate that G. metallireducens can grow via vanadium(V) respiration and that stimulating the activity of Geobacteraceae, and hence vanadium(V) reduction, can be an effective strategy for in situ immobilization of vanadium in contaminated subsurface environments.},
	keywords = {Anaerobiosis, Biodegradation, Environmental, Culture Media, Fresh Water, Geobacter, Geologic Sediments, Mining, Oxidation-Reduction, Vanadium, Water Pollution, Chemical},
	issn = {0099-2240},
	author = {Ortiz-Bernad, Irene and Anderson, Robert T and Vrionis, Helen A and Lovley, Derek R}
}
