@article {3154,
	title = {Characterization and transcription of arsenic respiration and resistance genes during in situ uranium bioremediation.},
	journal = {ISME J},
	volume = {7},
	year = {2013},
	month = {2013 Feb},
	pages = {370-83},
	abstract = {<p>The possibility of arsenic release and the potential role of Geobacter in arsenic biogeochemistry during in situ uranium bioremediation was investigated because increased availability of organic matter has been associated with substantial releases of arsenic in other subsurface environments. In a field experiment conducted at the Rifle, CO study site, groundwater arsenic concentrations increased when acetate was added. The number of transcripts from arrA, which codes for the α-subunit of dissimilatory As(V) reductase, and acr3, which codes for the arsenic pump protein Acr3, were determined with quantitative reverse transcription-PCR. Most of the arrA (>60\%) and acr3-1 (>90\%) sequences that were recovered were most similar to Geobacter species, while the majority of acr3-2 (>50\%) sequences were most closely related to Rhodoferax ferrireducens. Analysis of transcript abundance demonstrated that transcription of acr3-1 by the subsurface Geobacter community was correlated with arsenic concentrations in the groundwater. In contrast, Geobacter arrA transcript numbers lagged behind the major arsenic release and remained high even after arsenic concentrations declined. This suggested that factors other than As(V) availability regulated the transcription of arrA in situ, even though the presence of As(V) increased the transcription of arrA in cultures of Geobacter lovleyi, which was capable of As(V) reduction. These results demonstrate that subsurface Geobacter species can tightly regulate their physiological response to changes in groundwater arsenic concentrations. The transcriptomic approach developed here should be useful for the study of a diversity of other environments in which Geobacter species are considered to have an important influence on arsenic biogeochemistry.</p>},
	keywords = {Acetates, Arsenate Reductases, Arsenic, Biodegradation, Environmental, Colorado, Gene Expression Regulation, Bacterial, Genes, Bacterial, Geobacter, Groundwater, Transcriptome, Uranium},
	issn = {1751-7370},
	doi = {10.1038/ismej.2012.109},
	author = {Giloteaux, Ludovic and Holmes, Dawn E and Williams, Kenneth H and Wrighton, Kelly C and Wilkins, Michael J and Montgomery, Alison P and Smith, Jessica A and Orellana, Roberto and Thompson, Courtney A and Roper, Thomas J and Long, Philip E and Lovley, Derek R}
}
@article {3137,
	title = {U(VI) reduction by diverse outer surface c-type cytochromes of Geobacter sulfurreducens.},
	journal = {Appl Environ Microbiol},
	volume = {79},
	year = {2013},
	month = {2013 Oct},
	pages = {6369-74},
	abstract = {<p>Early studies with Geobacter sulfurreducens suggested that outer-surface c-type cytochromes might play a role in U(VI) reduction, but it has recently been suggested that there is substantial U(VI) reduction at the surface of the electrically conductive pili known as microbial nanowires. This phenomenon was further investigated. A strain of G. sulfurreducens, known as Aro-5, which produces pili with substantially reduced conductivity reduced U(VI) nearly as well as the wild type, as did a strain in which the gene for PilA, the structural pilin protein, was deleted. In order to reduce rates of U(VI) reduction to levels less than 20\% of the wild-type rates, it was necessary to delete the genes for the five most abundant outer surface c-type cytochromes of G. sulfurreducens. X-ray absorption near-edge structure spectroscopy demonstrated that whereas 83\% {\textpm} 10\% of the uranium associated with wild-type cells correspond to U(IV) after 4 h of incubation, with the quintuple mutant, 89\% {\textpm} 10\% of uranium was U(VI). Transmission electron microscopy and X-ray energy dispersion spectroscopy revealed that wild-type cells did not precipitate uranium along pili as previously reported, but U(IV) was precipitated at the outer cell surface. These findings are consistent with those of previous studies, which have suggested that G. sulfurreducens requires outer-surface c-type cytochromes but not pili for the reduction of soluble extracellular electron acceptors.</p>},
	keywords = {Cytochromes, Fimbriae, Bacterial, Gene Deletion, Geobacter, Microscopy, Electron, Transmission, Oxidation-Reduction, Uranium, X-Ray Absorption Spectroscopy},
	issn = {1098-5336},
	doi = {10.1128/AEM.02551-13},
	author = {Orellana, Roberto and Leavitt, Janet J and Comolli, Luis R and Csencsits, Roseann and Janot, Noemie and Flanagan, Kelly A and Gray, Arianna S and Leang, Ching and Izallalen, Mounir and Mester, T{\"u}nde and Lovley, Derek R}
}
