@article {3092,
	title = {Metatranscriptomic Evidence for Direct Interspecies Electron Transfer between Geobacter and Methanothrix Species in Methanogenic Rice Paddy Soils.},
	journal = {Appl Environ Microbiol},
	volume = {83},
	year = {2017},
	month = {2017 May 01},
	abstract = {<p>The possibility that  (formerly ) and  species cooperate via direct interspecies electron transfer (DIET) in terrestrial methanogenic environments was investigated in rice paddy soils. Genes with high sequence similarity to the gene for the PilA pilin monomer of the electrically conductive pili (e-pili) of  accounted for over half of the PilA gene sequences in metagenomic libraries and 42\% of the mRNA transcripts in RNA sequencing (RNA-seq) libraries. This abundance of e-pilin genes and transcripts is significant because e-pili can serve as conduits for DIET. Most of the e-pilin genes and transcripts were affiliated with  species, but sequences most closely related to putative e-pilin genes from genera such as , , , and , were also detected. Approximately 17\% of all metagenomic and metatranscriptomic bacterial sequences clustered with  species, and the finding that  spp. were actively transcribing growth-related genes indicated that they were metabolically active in the soils. Genes coding for e-pilin were among the most highly transcribed  genes. In addition, homologs of genes encoding OmcS, a -type cytochrome associated with the e-pili of  and required for DIET, were also highly expressed in the soils.  species in the soils highly expressed genes for enzymes involved in the reduction of carbon dioxide to methane. DIET is the only electron donor known to support CO reduction in  Thus, these results are consistent with a model in which  species were providing electrons to  species for methane production through electrical connections of e-pili. species are some of the most important microbial contributors to global methane production, but surprisingly little is known about their physiology and ecology. The possibility that DIET is a source of electrons for  in methanogenic rice paddy soils is important because it demonstrates that the contribution that  makes to methane production in terrestrial environments may extend beyond the conversion of acetate to methane. Furthermore, defined coculture studies have suggested that when  species receive some of their energy from DIET, they grow faster than when acetate is their sole energy source. Thus,  growth and metabolism in methanogenic soils may be faster and more robust than generally considered. The results also suggest that the reason that  species are repeatedly found to be among the most metabolically active microorganisms in methanogenic soils is that they grow syntrophically in cooperation with  spp., and possibly other methanogens, via DIET.</p>},
	keywords = {Carbon Dioxide, Electron Transport, Fimbriae Proteins, Gene Expression Profiling, Geobacter, Metagenome, Methane, Methanosarcinaceae, Oryza, Soil Microbiology},
	issn = {1098-5336},
	doi = {10.1128/AEM.00223-17},
	author = {Holmes, Dawn E and Shrestha, Pravin M and Walker, David J F and Dang, Yan and Nevin, Kelly P and Woodard, Trevor L and Lovley, Derek R}
}
@article {462,
	title = {Anode biofilm transcriptomics reveals outer surface components essential for high density current production in Geobacter sulfurreducens fuel cells.},
	journal = {PLoS One},
	volume = {4},
	year = {2009},
	month = {2009},
	pages = {e5628},
	abstract = {The mechanisms by which Geobacter sulfurreducens transfers electrons through relatively thick (>50 microm) biofilms to electrodes acting as a sole electron acceptor were investigated. Biofilms of Geobacter sulfurreducens were grown either in flow-through systems with graphite anodes as the electron acceptor or on the same graphite surface, but with fumarate as the sole electron acceptor. Fumarate-grown biofilms were not immediately capable of significant current production, suggesting substantial physiological differences from current-producing biofilms. Microarray analysis revealed 13 genes in current-harvesting biofilms that had significantly higher transcript levels. The greatest increases were for pilA, the gene immediately downstream of pilA, and the genes for two outer c-type membrane cytochromes, OmcB and OmcZ. Down-regulated genes included the genes for the outer-membrane c-type cytochromes, OmcS and OmcT. Results of quantitative RT-PCR of gene transcript levels during biofilm growth were consistent with microarray results. OmcZ and the outer-surface c-type cytochrome, OmcE, were more abundant and OmcS was less abundant in current-harvesting cells. Strains in which pilA, the gene immediately downstream from pilA, omcB, omcS, omcE, or omcZ was deleted demonstrated that only deletion of pilA or omcZ severely inhibited current production and biofilm formation in current-harvesting mode. In contrast, these gene deletions had no impact on biofilm formation on graphite surfaces when fumarate served as the electron acceptor. These results suggest that biofilms grown harvesting current are specifically poised for electron transfer to electrodes and that, in addition to pili, OmcZ is a key component in electron transfer through differentiated G. sulfurreducens biofilms to electrodes.},
	keywords = {Amino Acid Sequence, Bacterial Outer Membrane Proteins, Bioelectric Energy Sources, Biofilms, Cytochromes, Electrodes, Electron Transport, Fumarates, Gene Deletion, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Genetic Complementation Test, Geobacter, Microscopy, Confocal, Molecular Sequence Data, Oligonucleotide Array Sequence Analysis, Oxidation-Reduction, RNA, Messenger, Up-Regulation},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0005628},
	author = {Nevin, Kelly P and Kim, Byoung-Chan and Glaven, Richard H and Johnson, Jessica P and Woodard, Trevor L and Meth{\'e}, Barbara A and Didonato, Raymond J and Covalla, Sean F and Franks, Ashley E and Liu, Anna and Lovley, Derek R}
}
@article {503,
	title = {Genome-wide expression profiling in Geobacter sulfurreducens: identification of Fur and RpoS transcription regulatory sites in a relGsu mutant.},
	journal = {Funct Integr Genomics},
	volume = {7},
	year = {2007},
	month = {2007 Jul},
	pages = {229-55},
	abstract = {Rel(Gsu) is the single Geobacter sulfurreducens homolog of RelA and SpoT proteins found in many organisms. These proteins are involved in the regulation of levels of guanosine 3{\textquoteright}, 5{\textquoteright} bispyrophosphate, ppGpp, a molecule that signals slow growth and stress response under nutrient limitation in bacteria. We used information obtained from genome-wide expression profiling of the rel(Gsu) deletion mutant to identify putative regulatory sites involved in transcription networks modulated by Rel(Gsu) or ppGpp. Differential gene expression in the rel(Gsu) deletion mutant, as compared to the wild type, was available from two growth conditions, steady state chemostat cultures and stationary phase batch cultures. Hierarchical clustering analysis of these two datasets identified several groups of operons that are likely co-regulated. Using a search for conserved motifs in the upstream regions of these co-regulated operons, we identified sequences similar to Fur- and RpoS-regulated sites. These findings suggest that Fur- and RpoS-dependent gene expression in G. sulfurreducens is affected by Rel(Gsu)-mediated signaling.},
	keywords = {Bacterial Proteins, Base Sequence, Gene Deletion, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Genes, Bacterial, Genome, Bacterial, Geobacter, Ligases, Mutation, Operon, Promoter Regions, Genetic, Regulatory Sequences, Nucleic Acid, Repressor Proteins, Sigma Factor, Transcription, Genetic},
	issn = {1438-793X},
	doi = {10.1007/s10142-007-0048-5},
	author = {Krushkal, Julia and Yan, Bin and DiDonato, Laurie N and Puljic, Marko and Nevin, Kelly P and Woodard, Trevor L and Adkins, Ronald M and Meth{\'e}, Barbara A and Lovley, Derek R}
}
@article {499,
	title = {Involvement of Geobacter sulfurreducens SfrAB in acetate metabolism rather than intracellular, respiration-linked Fe(III) citrate reduction.},
	journal = {Microbiology},
	volume = {153},
	year = {2007},
	month = {2007 Oct},
	pages = {3572-85},
	abstract = {A soluble ferric reductase, SfrAB, which catalysed the NADPH-dependent reduction of chelated Fe(III), was previously purified from the dissimilatory Fe(III)-reducing micro-organism Geobacter sulfurreducens, suggesting that reduction of chelated forms of Fe(III) might be cytoplasmic. However, metabolically active spheroplast suspensions could not catalyse acetate-dependent Fe(III) citrate reduction, indicating that periplasmic and/or outer-membrane components were required for Fe(III) citrate reduction. Furthermore, phenotypic analysis of an SfrAB knockout mutant suggested that SfrAB was involved in acetate metabolism rather than respiration-linked Fe(III) reduction. The mutant could not grow via the reduction of either Fe(III) citrate or fumarate when acetate was the electron donor but could grow with either acceptor if either hydrogen or formate served as the electron donor. Following prolonged incubation in acetate : fumarate medium in the absence of hydrogen and formate, an {\textquoteright}acetate-adapted{\textquoteright} SfrAB-null strain was isolated that was capable of growth on acetate : fumarate medium but not acetate : Fe(III) citrate medium. Comparison of gene expression in this strain with that of the wild-type revealed upregulation of a potential NADPH-dependent ferredoxin oxidoreductase as well as genes involved in energy generation and amino acid uptake, suggesting that NADPH homeostasis and the tricarboxylic acid (TCA) cycle were perturbed in the {\textquoteright}acetate-adapted{\textquoteright} SfrAB-null strain. Membrane and soluble fractions prepared from the {\textquoteright}acetate-adapted{\textquoteright} strain were depleted of NADPH-dependent Fe(III), viologen and quinone reductase activities. These results indicate that cytoplasmic, respiration-linked reduction of Fe(III) by SfrAB in vivo is unlikely and suggest that deleting SfrAB may interfere with growth via acetate oxidation by interfering with NADP regeneration.},
	keywords = {Acetates, Amino Acid Transport Systems, Bacterial Proteins, Cell Membrane, Citric Acid Cycle, Cytoplasm, Energy Metabolism, Ferric Compounds, Formic Acids, Fumarates, Gene Deletion, Gene Expression Profiling, Geobacter, Hydrogen, NADH, NADPH Oxidoreductases, Oligonucleotide Array Sequence Analysis},
	issn = {1350-0872},
	doi = {10.1099/mic.0.2007/006478-0},
	author = {Coppi, Maddalena V and O{\textquoteright}Neil, Regina A and Leang, Ching and Kaufmann, Franz and Meth{\'e}, Barbara A and Nevin, Kelly P and Woodard, Trevor L and Liu, Anna and Lovley, Derek R}
}
