<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ueki, Toshiyuki</style></author><author><style face="normal" font="default" size="100%">Walker, David J F</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Ward, Joy E</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Nonnenmann, Stephen S</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Generation of High Current Densities in Geobacter sulfurreducens Lacking the Putative Gene for the PilB Pilus Assembly Motor.</style></title><secondary-title><style face="normal" font="default" size="100%">Microbiol Spectr</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Microbiol Spectr</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Bacterial Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Electric Conductivity</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Gene Deletion</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Geologic Sediments</style></keyword><keyword><style  face="normal" font="default" size="100%">Microscopy, Atomic Force</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxidoreductases</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2021</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2021 Oct 31</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">9</style></volume><pages><style face="normal" font="default" size="100%">e0087721</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Geobacter sulfurreducens is commonly employed as a model for the study of extracellular electron transport mechanisms in the  species. Deletion of , which is known to encode the pilus assembly motor protein for type IV pili in other bacteria, has been proposed as an effective strategy for evaluating the role of electrically conductive pili (e-pili) in G. sulfurreducens extracellular electron transfer. In those studies, the inhibition of e-pili expression associated with  deletion was not demonstrated directly but was inferred from the observation that  deletion mutants produced lower current densities than wild-type cells. Here, we report that deleting  did not diminish current production. Conducting probe atomic force microscopy revealed filaments with the same diameter and similar current-voltage response as e-pili harvested from wild-type G. sulfurreducens or when e-pili are expressed heterologously from the G. sulfurreducens pilin gene in Escherichia coli. Immunogold labeling demonstrated that a G. sulfurreducens strain expressing a pilin monomer with a His tag continued to express His tag-labeled filaments when  was deleted. These results suggest that a reinterpretation of the results of previous studies on G. sulfurreducens  deletion strains may be necessary.  Geobacter sulfurreducens is a model microbe for the study of biogeochemically and technologically significant processes, such as the reduction of Fe(III) oxides in soils and sediments, bioelectrochemical applications that produce electric current from waste organic matter or drive useful processes with the consumption of renewable electricity, direct interspecies electron transfer in anaerobic digestors and methanogenic soils and sediments, and metal corrosion. Elucidating the phenotypes associated with gene deletions is an important strategy for determining the mechanisms for extracellular electron transfer in G. sulfurreducens. The results reported here demonstrate that we cannot replicate the key phenotype reported for a gene deletion that has been central to the development of models for long-range electron transport in G. sulfurreducens.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/34585977?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ueki, Toshiyuki</style></author><author><style face="normal" font="default" size="100%">Walker, David J F</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Nonnenmann, Stephen S</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">An  Chassis for Production of Electrically Conductive Protein Nanowires.</style></title><secondary-title><style face="normal" font="default" size="100%">ACS Synth Biol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">ACS Synth Biol</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Electric Conductivity</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Graphite</style></keyword><keyword><style  face="normal" font="default" size="100%">Microorganisms, Genetically-Modified</style></keyword><keyword><style  face="normal" font="default" size="100%">Microscopy, Atomic Force</style></keyword><keyword><style  face="normal" font="default" size="100%">Nanowires</style></keyword><keyword><style  face="normal" font="default" size="100%">Operon</style></keyword><keyword><style  face="normal" font="default" size="100%">Protein Engineering</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2020</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2020 Mar 20</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">9</style></volume><pages><style face="normal" font="default" size="100%">647-654</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt; pilin-based electrically conductive protein nanowires (e-PNs) are a revolutionary electronic material. They offer novel options for electronic sensing applications and have the remarkable ability to harvest electrical energy from atmospheric humidity. However, technical constraints limit mass cultivation and genetic manipulation of . Therefore, we designed a strain of  to express e-PNs by introducing a plasmid that contained an inducible operon with  genes for type IV pili biogenesis machinery and a synthetic gene designed to yield a peptide monomer that could be assembled into e-PNs. The e-PNs expressed in  and harvested with a simple filtration method had the same diameter (3 nm) and conductance as e-PNs expressed in . These results, coupled with the robustness of  for mass cultivation and the extensive  toolbox for genetic manipulation, greatly expand the opportunities for large-scale fabrication of novel e-PNs.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/32125829?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Walker, David J F</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Holmes, Dawn E</style></author><author><style face="normal" font="default" size="100%">Rotaru, Amelia-Elena</style></author><author><style face="normal" font="default" size="100%">Ward, Joy E</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Zhu, Jiaxin</style></author><author><style face="normal" font="default" size="100%">Ueki, Toshiyuki</style></author><author><style face="normal" font="default" size="100%">Nonnenmann, Stephen S</style></author><author><style face="normal" font="default" size="100%">McInerney, Michael J</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Syntrophus conductive pili demonstrate that common hydrogen-donating syntrophs can have a direct electron transfer option.</style></title><secondary-title><style face="normal" font="default" size="100%">ISME J</style></secondary-title><alt-title><style face="normal" font="default" size="100%">ISME J</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Deltaproteobacteria</style></keyword><keyword><style  face="normal" font="default" size="100%">Electric Conductivity</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Electrons</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Formates</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrogen</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2020</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2020 Mar</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">14</style></volume><pages><style face="normal" font="default" size="100%">837-846</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Heterologous expression of the putative S. aciditrophicus type IV pilin gene in Geobacter sulfurreducens yielded conductive pili of the same diameter (4 nm) and conductance of the native S. aciditrophicus pili and enabled long-range electron transport in G. sulfurreducens. S. aciditrophicus lacked abundant c-type cytochromes often associated with DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/31896792?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Walker, David Jf</style></author><author><style face="normal" font="default" size="100%">Adhikari, Ramesh Y</style></author><author><style face="normal" font="default" size="100%">Holmes, Dawn E</style></author><author><style face="normal" font="default" size="100%">Ward, Joy E</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Electrically conductive pili from pilin genes of phylogenetically diverse microorganisms.</style></title><secondary-title><style face="normal" font="default" size="100%">ISME J</style></secondary-title><alt-title><style face="normal" font="default" size="100%">ISME J</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Deltaproteobacteria</style></keyword><keyword><style  face="normal" font="default" size="100%">Electric Conductivity</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Methane</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxidation-Reduction</style></keyword><keyword><style  face="normal" font="default" size="100%">Phylogeny</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2018</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2018 Jan</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">12</style></volume><pages><style face="normal" font="default" size="100%">48-58</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The possibility that bacteria other than Geobacter species might contain genes for electrically conductive pili (e-pili) was investigated by heterologously expressing pilin genes of interest in Geobacter sulfurreducens. Strains of G. sulfurreducens producing high current densities, which are only possible with e-pili, were obtained with pilin genes from Flexistipes sinusarabici, Calditerrivibrio nitroreducens and Desulfurivibrio alkaliphilus. The conductance of pili from these strains was comparable to native G. sulfurreducens e-pili. The e-pili derived from C. nitroreducens, and D. alkaliphilus pilin genes are the first examples of relatively long (&gt;100 amino acids) pilin monomers assembling into e-pili. The pilin gene from Candidatus Desulfofervidus auxilii did not yield e-pili, suggesting that the hypothesis that this sulfate reducer wires itself with e-pili to methane-oxidizing archaea to enable anaerobic methane oxidation should be reevaluated. A high density of aromatic amino acids and a lack of substantial aromatic-free gaps along the length of long pilins may be important characteristics leading to e-pili. This study demonstrates a simple method to screen pilin genes from difficult-to-culture microorganisms for their potential to yield e-pili; reveals new sources for biologically based electronic materials; and suggests that a wide phylogenetic diversity of microorganisms may use e-pili for extracellular electron exchange.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/28872631?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ueki, Toshiyuki</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Rotaru, Amelia-Elena</style></author><author><style face="normal" font="default" size="100%">Wang, Li-Ying</style></author><author><style face="normal" font="default" size="100%">Ward, Joy E</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%"> Strains Expressing Poorly Conductive Pili Reveal Constraints on Direct Interspecies Electron Transfer Mechanisms.</style></title><secondary-title><style face="normal" font="default" size="100%">mBio</style></secondary-title><alt-title><style face="normal" font="default" size="100%">mBio</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cytochromes</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferric Compounds</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Microbial Interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxidation-Reduction</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2018</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2018 Jul 10</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">9</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Cytochrome-to-cytochrome electron transfer and electron transfer along conduits of multiple extracellular magnetite grains are often proposed as strategies for direct interspecies electron transfer (DIET) that do not require electrically conductive pili (e-pili). However, physical evidence for these proposed DIET mechanisms has been lacking. To investigate these possibilities further, we constructed  strain Aro-5, in which the wild-type pilin gene was replaced with the  pilin gene that was previously shown to yield poorly conductive pili in  strain Aro-5.  strain Aro-5 did not reduce Fe(III) oxide and produced only low current densities, phenotypes consistent with expression of poorly conductive pili. Like  strain Aro-5,  strain Aro-5 displayed abundant outer surface cytochromes. Cocultures initiated with wild-type  as the electron-donating strain and  strain Aro-5 as the electron-accepting strain grew via DIET. However,  Aro-5/ wild-type cocultures did not. Cocultures initiated with the Aro-5 strains of both species grew only when amended with granular activated carbon (GAC), a conductive material known to be a conduit for DIET. Magnetite could not substitute for GAC. The inability of the two Aro-5 strains to adapt for DIET in the absence of GAC suggests that there are physical constraints on establishing DIET solely through cytochrome-to-cytochrome electron transfer or along chains of magnetite. The finding that DIET is possible with electron-accepting partners that lack highly conductive pili greatly expands the range of potential electron-accepting partners that might participate in DIET. DIET is thought to be an important mechanism for interspecies electron exchange in natural anaerobic soils and sediments in which methane is either produced or consumed, as well as in some photosynthetic mats and anaerobic digesters converting organic wastes to methane. Understanding the potential mechanisms for DIET will not only aid in modeling carbon and electron flow in these geochemically significant environments but will also be helpful for interpreting meta-omic data from as-yet-uncultured microbes in DIET-based communities and for designing strategies to promote DIET in anaerobic digesters. The results demonstrate the need to develop a better understanding of the diversity of types of e-pili in the microbial world to identify potential electron-donating partners for DIET. Novel methods for recovering as-yet-uncultivated microorganisms capable of DIET in culture will be needed to further evaluate whether DIET is possible without e-pili in the absence of conductive materials such as GAC.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">4</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/29991583?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tan, Yang</style></author><author><style face="normal" font="default" size="100%">Adhikari, Ramesh Y</style></author><author><style face="normal" font="default" size="100%">Malvankar, Nikhil S</style></author><author><style face="normal" font="default" size="100%">Pi, Shuang</style></author><author><style face="normal" font="default" size="100%">Ward, Joy E</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Xia, Qiangfei</style></author><author><style face="normal" font="default" size="100%">Tuominen, Mark T</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Synthetic Biological Protein Nanowires with High Conductivity.</style></title><secondary-title><style face="normal" font="default" size="100%">Small</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Small</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Amino Acid Sequence</style></keyword><keyword><style  face="normal" font="default" size="100%">Electric Conductivity</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Nanowires</style></keyword><keyword><style  face="normal" font="default" size="100%">Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Tryptophan</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2016</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2016 Sep</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">12</style></volume><pages><style face="normal" font="default" size="100%">4481-5</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Genetic modification to add tryptophan to PilA, the monomer for the electrically conductive pili of Geobacter sulfurreducens, yields conductive protein filaments 2000-fold more conductive than the wild-type pili while cutting the diameter in half to 1.5 nm.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">33</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/27409066?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Liu, Fanghua</style></author><author><style face="normal" font="default" size="100%">Rotaru, Amelia-Elena</style></author><author><style face="normal" font="default" size="100%">Shrestha, Pravin M</style></author><author><style face="normal" font="default" size="100%">Malvankar, Nikhil S</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Magnetite compensates for the lack of a pilin-associated c-type cytochrome in extracellular electron exchange.</style></title><secondary-title><style face="normal" font="default" size="100%">Environ Microbiol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Environ Microbiol</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cytochrome c Group</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Electrons</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferrosoferric Oxide</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Gene Expression Regulation, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Heme</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxides</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2015</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2015 Mar</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">17</style></volume><pages><style face="normal" font="default" size="100%">648-55</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Nanoscale magnetite can facilitate microbial extracellular electron transfer that plays an important role in biogeochemical cycles, bioremediation and several bioenergy strategies, but the mechanisms for the stimulation of extracellular electron transfer are poorly understood. Further investigation revealed that magnetite attached to the electrically conductive pili of Geobacter species in a manner reminiscent of the association of the multi-heme c-type cytochrome OmcS with the pili of Geobacter sulfurreducens. Magnetite conferred extracellular electron capabilities on an OmcS-deficient strain unable to participate in interspecies electron transfer or Fe(III) oxide reduction. In the presence of magnetite wild-type cells repressed expression of the OmcS gene, suggesting that cells might need to produce less OmcS when magnetite was available. The finding that magnetite can compensate for the lack of the electron transfer functions of a multi-heme c-type cytochrome has implications not only for the function of modern microbes, but also for the early evolution of microbial electron transport mechanisms.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/24725505?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Rotaru, Amelia-Elena</style></author><author><style face="normal" font="default" size="100%">Shrestha, Pravin Malla</style></author><author><style face="normal" font="default" size="100%">Liu, Fanghua</style></author><author><style face="normal" font="default" size="100%">Markovaite, Beatrice</style></author><author><style face="normal" font="default" size="100%">Chen, Shanshan</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Direct interspecies electron transfer between Geobacter metallireducens and Methanosarcina barkeri.</style></title><secondary-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Biological Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Ethanol</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">Methane</style></keyword><keyword><style  face="normal" font="default" size="100%">Methanosarcina barkeri</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2014</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2014 Aug</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">80</style></volume><pages><style face="normal" font="default" size="100%">4599-605</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Direct interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the diversity of methanogens capable of DIET. The ability of Methanosarcina barkeri to participate in DIET was evaluated in coculture with Geobacter metallireducens. Cocultures formed aggregates that shared electrons via DIET during the stoichiometric conversion of ethanol to methane. Cocultures could not be initiated with a pilin-deficient G. metallireducens strain, suggesting that long-range electron transfer along pili was important for DIET. Amendments of granular activated carbon permitted the pilin-deficient G. metallireducens isolates to share electrons with M. barkeri, demonstrating that this conductive material could substitute for pili in promoting DIET. When M. barkeri was grown in coculture with the H2-producing Pelobacter carbinolicus, incapable of DIET, M. barkeri utilized H2 as an electron donor but metabolized little of the acetate that P.carbinolicus produced. This suggested that H2, but not electrons derived from DIET, inhibited acetate metabolism. P. carbinolicus-M. barkeri cocultures did not aggregate, demonstrating that, unlike DIET, close physical contact was not necessary for interspecies H2 transfer. M. barkeri is the second methanogen found to accept electrons via DIET and the first methanogen known to be capable of using either H2 or electrons derived from DIET for CO2 reduction. Furthermore, M. barkeri is genetically tractable,making it a model organism for elucidating mechanisms by which methanogens make biological electrical connections with other cells.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">15</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/24837373?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Liu, Xing</style></author><author><style face="normal" font="default" size="100%">Tremblay, Pier-Luc</style></author><author><style face="normal" font="default" size="100%">Malvankar, Nikhil S</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author><author><style face="normal" font="default" size="100%">Vargas, Madeline</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A Geobacter sulfurreducens strain expressing pseudomonas aeruginosa type IV pili localizes OmcS on pili but is deficient in Fe(III) oxide reduction and current production.</style></title><secondary-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Amino Acid Sequence</style></keyword><keyword><style  face="normal" font="default" size="100%">Cytochromes c</style></keyword><keyword><style  face="normal" font="default" size="100%">Electricity</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferric Compounds</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Methanosarcinaceae</style></keyword><keyword><style  face="normal" font="default" size="100%">Molecular Sequence Data</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxidation-Reduction</style></keyword><keyword><style  face="normal" font="default" size="100%">Pseudomonas aeruginosa</style></keyword><keyword><style  face="normal" font="default" size="100%">Sequence Alignment</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2014</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2014 Feb</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">80</style></volume><pages><style face="normal" font="default" size="100%">1219-24</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The conductive pili of Geobacter species play an important role in electron transfer to Fe(III) oxides, in long-range electron transport through current-producing biofilms, and in direct interspecies electron transfer. Although multiple lines of evidence have indicated that the pili of Geobacter sulfurreducens have a metal-like conductivity, independent of the presence of c-type cytochromes, this claim is still controversial. In order to further investigate this phenomenon, a strain of G. sulfurreducens, designated strain PA, was constructed in which the gene for the native PilA, the structural pilin protein, was replaced with the PilA gene of Pseudomonas aeruginosa PAO1. Strain PA expressed and properly assembled P. aeruginosa PilA subunits into pili and exhibited a profile of outer surface c-type cytochromes similar to that of a control strain expressing the G. sulfurreducens PilA. Surprisingly, the strain PA pili were decorated with the c-type cytochrome OmcS in a manner similar to the control strain. However, the strain PA pili were 14-fold less conductive than the pili of the control strain, and strain PA was severely impaired in Fe(III) oxide reduction and current production. These results demonstrate that the presence of OmcS on pili is not sufficient to confer conductivity to pili and suggest that there are unique structural features of the G. sulfurreducens PilA that are necessary for conductivity.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/24296506?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Smith, Jessica A</style></author><author><style face="normal" font="default" size="100%">Tremblay, Pier-Luc</style></author><author><style face="normal" font="default" size="100%">Shrestha, Pravin Malla</style></author><author><style face="normal" font="default" size="100%">Snoeyenbos-West, Oona L</style></author><author><style face="normal" font="default" size="100%">Franks, Ashley E</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Going wireless: Fe(III) oxide reduction without pili by Geobacter sulfurreducens strain JS-1.</style></title><secondary-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Adaptation, Physiological</style></keyword><keyword><style  face="normal" font="default" size="100%">Biofilms</style></keyword><keyword><style  face="normal" font="default" size="100%">DNA, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferric Compounds</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Gene Deletion</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Oligonucleotide Array Sequence Analysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Proteomics</style></keyword><keyword><style  face="normal" font="default" size="100%">Sequence Analysis, DNA</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2014</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2014 Jul</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">80</style></volume><pages><style face="normal" font="default" size="100%">4331-40</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Previous studies have suggested that the conductive pili of Geobacter sulfurreducens are essential for extracellular electron transfer to Fe(III) oxides and for optimal long-range electron transport through current-producing biofilms. The KN400 strain of G. sulfurreducens reduces poorly crystalline Fe(III) oxide more rapidly than the more extensively studied DL-1 strain. Deletion of the gene encoding PilA, the structural pilin protein, in strain KN400 inhibited Fe(III) oxide reduction. However, low rates of Fe(III) reduction were detected after extended incubation (&gt;30 days) in the presence of Fe(III) oxide. After seven consecutive transfers, the PilA-deficient strain adapted to reduce Fe(III) oxide as fast as the wild type. Microarray, whole-genome resequencing, proteomic, and gene deletion studies indicated that this adaptation was associated with the production of larger amounts of the c-type cytochrome PgcA, which was released into the culture medium. It is proposed that the extracellular cytochrome acts as an electron shuttle, promoting electron transfer from the outer cell surface to Fe(III) oxides. The adapted PilA-deficient strain competed well with the wild-type strain when both were grown together on Fe(III) oxide. However, when 50% of the culture medium was replaced with fresh medium every 3 days, the wild-type strain outcompeted the adapted strain. A possible explanation for this is that the necessity to produce additional PgcA, to replace the PgcA being continually removed, put the adapted strain at a competitive disadvantage, similar to the apparent selection against electron shuttle-producing Fe(III) reducers in many anaerobic soils and sediments. Despite increased extracellular cytochrome production, the adapted PilA-deficient strain produced low levels of current, consistent with the concept that long-range electron transport through G. sulfurreducens biofilms is more effective via pili.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">14</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/24814783?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Vargas, Madeline</style></author><author><style face="normal" font="default" size="100%">Malvankar, Nikhil S</style></author><author><style face="normal" font="default" size="100%">Tremblay, Pier-Luc</style></author><author><style face="normal" font="default" size="100%">Leang, Ching</style></author><author><style face="normal" font="default" size="100%">Smith, Jessica A</style></author><author><style face="normal" font="default" size="100%">Patel, Pranav</style></author><author><style face="normal" font="default" size="100%">Snoeyenbos-West, Oona</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Aromatic amino acids required for pili conductivity and long-range extracellular electron transport in Geobacter sulfurreducens.</style></title><secondary-title><style face="normal" font="default" size="100%">mBio</style></secondary-title><alt-title><style face="normal" font="default" size="100%">mBio</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Amino Acids, Aromatic</style></keyword><keyword><style  face="normal" font="default" size="100%">Bioelectric Energy Sources</style></keyword><keyword><style  face="normal" font="default" size="100%">Biofilms</style></keyword><keyword><style  face="normal" font="default" size="100%">Electricity</style></keyword><keyword><style  face="normal" font="default" size="100%">Electrodes</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferric Compounds</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Graphite</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2013</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2013 Mar 12</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">4</style></volume><pages><style face="normal" font="default" size="100%">e00105-13</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;b&gt;UNLABELLED: &lt;/b&gt;It has been proposed that Geobacter sulfurreducens requires conductive pili for long-range electron transport to Fe(III) oxides and for high-density current production in microbial fuel cells. In order to investigate this further, we constructed a strain of G. sulfurreducens, designated Aro-5, which produced pili with diminished conductivity. This was accomplished by modifying the amino acid sequence of PilA, the structural pilin protein. An alanine was substituted for each of the five aromatic amino acids in the carboxyl terminus of PilA, the region in which G. sulfurreducens PilA differs most significantly from the PilAs of microorganisms incapable of long-range extracellular electron transport. Strain Aro-5 produced pili that were properly decorated with the multiheme c-type cytochrome OmcS, which is essential for Fe(III) oxide reduction. However, pili preparations of the Aro-5 strain had greatly diminished conductivity and Aro-5 cultures were severely limited in their capacity to reduce Fe(III) compared to the control strain. Current production of the Aro-5 strain, with a graphite anode serving as the electron acceptor, was less than 10% of that of the control strain. The conductivity of the Aro-5 biofilms was 10-fold lower than the control strain's. These results demonstrate that the pili of G. sulfurreducens must be conductive in order for the cells to be effective in extracellular long-range electron transport.&lt;/p&gt;&lt;p&gt;&lt;b&gt;IMPORTANCE: &lt;/b&gt;Extracellular electron transfer by Geobacter species plays an important role in the biogeochemistry of soils and sediments and has a number of bioenergy applications. For example, microbial reduction of Fe(III) oxide is one of the most geochemically significant processes in anaerobic soils, aquatic sediments, and aquifers, and Geobacter organisms are often abundant in such environments. Geobacter sulfurreducens produces the highest current densities of any known pure culture, and close relatives are often the most abundant organisms colonizing anodes in microbial fuel cells that harvest electricity from wastewater or aquatic sediments. The finding that a strain of G. sulfurreducens that produces pili with low conductivity is limited in these extracellular electron transport functions provides further insight into these environmentally significant processes.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><custom1><style face="normal" font="default" size="100%">https://www.ncbi.nlm.nih.gov/pubmed/23481602?dopt=Abstract</style></custom1></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Reguera, Gemma</style></author><author><style face="normal" font="default" size="100%">Nevin, Kelly P</style></author><author><style face="normal" font="default" size="100%">Nicoll, Julie S</style></author><author><style face="normal" font="default" size="100%">Covalla, Sean F</style></author><author><style face="normal" font="default" size="100%">Woodard, Trevor L</style></author><author><style face="normal" font="default" size="100%">Lovley, Derek R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Biofilm and nanowire production leads to increased current in Geobacter sulfurreducens fuel cells.</style></title><secondary-title><style face="normal" font="default" size="100%">Appl Environ Microbiol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Appl. Environ. Microbiol.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Acetates</style></keyword><keyword><style  face="normal" font="default" size="100%">Bioelectric Energy Sources</style></keyword><keyword><style  face="normal" font="default" size="100%">Biofilms</style></keyword><keyword><style  face="normal" font="default" size="100%">Electricity</style></keyword><keyword><style  face="normal" font="default" size="100%">Electrodes</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Fimbriae, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Geobacter</style></keyword><keyword><style  face="normal" font="default" size="100%">Microscopy, Confocal</style></keyword><keyword><style  face="normal" font="default" size="100%">Mutation</style></keyword><keyword><style  face="normal" font="default" size="100%">Nanowires</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2006 Nov</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">72</style></volume><pages><style face="normal" font="default" size="100%">7345-8</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Geobacter sulfurreducens developed highly structured, multilayer biofilms on the anode surface of a microbial fuel cell converting acetate to electricity. Cells at a distance from the anode remained viable, and there was no decrease in the efficiency of current production as the thickness of the biofilm increased. Genetic studies demonstrated that efficient electron transfer through the biofilm required the presence of electrically conductive pili. These pili may represent an electronic network permeating the biofilm that can promote long-range electrical transfer in an energy-efficient manner, increasing electricity production more than 10-fold.</style></abstract><issue><style face="normal" font="default" size="100%">11</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/16936064?dopt=Abstract</style></custom1></record></records></xml>