@article {3143,
	title = {Fluctuations in species-level protein expression occur during element and nutrient cycling in the subsurface.},
	journal = {PLoS One},
	volume = {8},
	year = {2013},
	month = {2013},
	pages = {e57819},
	abstract = {<p>While microbial activities in environmental systems play a key role in the utilization and cycling of essential elements and compounds, microbial activity and growth frequently fluctuates in response to environmental stimuli and perturbations. To investigate these fluctuations within a saturated aquifer system, we monitored a carbon-stimulated in situ Geobacter population while iron reduction was occurring, using 16S rRNA abundances and high-resolution tandem mass spectrometry proteome measurements. Following carbon amendment, 16S rRNA analysis of temporally separated samples revealed the rapid enrichment of Geobacter-like environmental strains with strong similarity to G. bemidjiensis. Tandem mass spectrometry proteomics measurements suggest high carbon flux through Geobacter respiratory pathways, and the synthesis of anapleurotic four carbon compounds from acetyl-CoA via pyruvate ferredoxin oxidoreductase activity. Across a 40-day period where Fe(III) reduction was occurring, fluctuations in protein expression reflected changes in anabolic versus catabolic reactions, with increased levels of biosynthesis occurring soon after acetate arrival in the aquifer. In addition, localized shifts in nutrient limitation were inferred based on expression of nitrogenase enzymes and phosphate uptake proteins. These temporal data offer the first example of differing microbial protein expression associated with changing geochemical conditions in a subsurface environment.</p>},
	keywords = {Biomass, Carbon, Environment, Gene Expression Regulation, Bacterial, Geobacter, Groundwater, Humic Substances, Iron, Oxidation-Reduction, Phosphates, Plankton, Proteomics, RNA, Ribosomal, 16S, Tandem Mass Spectrometry, Uranium, Vanadium, Water Microbiology},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0057819},
	author = {Wilkins, Michael J and Wrighton, Kelly C and Nicora, Carrie D and Williams, Kenneth H and McCue, Lee Ann and Handley, Kim M and Miller, Chris S and Giloteaux, Ludovic and Montgomery, Alison P and Lovley, Derek R and Banfield, Jillian F and Long, Philip E and Lipton, Mary S}
}
@article {451,
	title = {Molecular analysis of phosphate limitation in Geobacteraceae during the bioremediation of a uranium-contaminated aquifer.},
	journal = {ISME J},
	volume = {4},
	year = {2010},
	month = {2010 Feb},
	pages = {253-66},
	abstract = {Nutrient limitation is an environmental stress that may reduce the effectiveness of bioremediation strategies, especially when the contaminants are organic compounds or when organic compounds are added to promote microbial activities such as metal reduction. Genes indicative of phosphate-limitation were identified by microarray analysis of chemostat cultures of Geobacter sulfureducens. This analysis revealed that genes in the pst-pho operon, which is associated with a high-affinity phosphate uptake system in other microorganisms, had significantly higher transcript abundance under phosphate-limiting conditions, with the genes pstB and phoU upregulated the most. Quantitative PCR analysis of pstB and phoU transcript levels in G. sulfurreducens grown in chemostats demonstrated that the expression of these genes increased when phosphate was removed from the culture medium. Transcripts of pstB and phoU within the subsurface Geobacter species predominating during an in situ uranium-bioremediation field experiment were more abundant than in chemostat cultures of G. sulfurreducens that were not limited for phosphate. Addition of phosphate to incubations of subsurface sediments did not stimulate dissimilatory metal reduction. The added phosphate was rapidly adsorbed onto the sediments. The results demonstrate that Geobacter species can effectively reduce U(VI) even when experiencing suboptimal phosphate concentrations and that increasing phosphate availability with phosphate additions is difficult to achieve because of the high reactivity of this compound. This transcript-based approach developed for diagnosing phosphate limitation should be applicable to assessing the potential need for additional phosphate in other bioremediation processes.},
	keywords = {Biodegradation, Environmental, Fresh Water, Gene Expression Regulation, Bacterial, Geobacter, Phosphates, Uranium, Water Pollutants},
	issn = {1751-7370},
	doi = {10.1038/ismej.2009.115},
	author = {N{\textquoteright}guessan, Lucie A and Elifantz, Hila and Nevin, Kelly P and Mouser, Paula J and Meth{\'e}, Barbara and Woodard, Trevor L and Manley, Kimberly and Williams, Kenneth H and Wilkins, Michael J and Larsen, Joern T and Long, Philip E and Lovley, Derek R}
}
