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When Is A Microbial Culture "Pure"? Persistent Cryptic Contaminant Escapes Detection Even With Deep Genome Sequencing, Pravin Malla, Kelly P. Nevin, Minita Shrestha, Derek R. Lovley Jan 2013

When Is A Microbial Culture "Pure"? Persistent Cryptic Contaminant Escapes Detection Even With Deep Genome Sequencing, Pravin Malla, Kelly P. Nevin, Minita Shrestha, Derek R. Lovley

Derek Lovley

Geobacter sulfurreducens strain KN400 was recovered in previous studies in which a culture of the DL1 strain of G. sulfurreducens served as the inoculum in investigations of microbial current production at low anode potentials (_400 mV versus Ag/AgCl). Differences in the genome sequences of KN400 and DL1 were too great to have arisen from adaptive evolution during growth on the anode. Previous deep sequencing (80-fold coverage) of the DL1 culture failed to detect sequences specific to KN400, suggesting that KN400 was an external contaminant inadvertently introduced into the anode culturing system. In order to evaluate this further, a portion ...


Aromatic Amino Acids Required For Pili Conductivity And Long-Range Extracellular Electron Transport In Geobacter Sulfurreducens, Madeline Vargas, Nikhil S. Malvankar, Pier-Luc Tremblay, Ching Leang, Jessica A. Smith, Pranav Patel, Oona Synoeyenbos-West, Kelly P. Nevin, Derek R. Lovley Jan 2013

Aromatic Amino Acids Required For Pili Conductivity And Long-Range Extracellular Electron Transport In Geobacter Sulfurreducens, Madeline Vargas, Nikhil S. Malvankar, Pier-Luc Tremblay, Ching Leang, Jessica A. Smith, Pranav Patel, Oona Synoeyenbos-West, Kelly P. Nevin, Derek R. Lovley

Derek Lovley

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 ...


Fluctuations In Species-Level Protein Expression Occur During Element And Nutrient Cycling In The Subsurface, Michael J. Wilkins, Kelly C. Wrighton, Carrie D. Nicora, Kenneth H. Williams, Lee Ann Mccue, Kim M. Handley, Chris S. Miller, Ludovic Giloteaux, Alison P. Montogomery, Derek R. Lovley, Jillian F. Banfield, Philip E. Long, Mary S. Lipton Jan 2013

Fluctuations In Species-Level Protein Expression Occur During Element And Nutrient Cycling In The Subsurface, Michael J. Wilkins, Kelly C. Wrighton, Carrie D. Nicora, Kenneth H. Williams, Lee Ann Mccue, Kim M. Handley, Chris S. Miller, Ludovic Giloteaux, Alison P. Montogomery, Derek R. Lovley, Jillian F. Banfield, Philip E. Long, Mary S. Lipton

Derek Lovley

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 ...


Improved Cathode Materials For Microbial Eletrosynthesis, Tian Zhang, Huarong Nie, Timothy S. Bain, Haiyun Lu, Mengmeng Cui, Oona L. Snoeyenbos-West, Ashley E. Franks, Kelly P. Nevin, Thomas P. Russell, Derek R. Lovley Jan 2013

Improved Cathode Materials For Microbial Eletrosynthesis, Tian Zhang, Huarong Nie, Timothy S. Bain, Haiyun Lu, Mengmeng Cui, Oona L. Snoeyenbos-West, Ashley E. Franks, Kelly P. Nevin, Thomas P. Russell, Derek R. Lovley

Derek Lovley

Microbial electrosynthesis is a promising strategy for the microbial conversion of carbon dioxide to transportation fuels and other organic commodities, but optimization of this process is required for commercialization. Cathodes which enhance electrode–microbe electron transfer might improve rates of product formation. To evaluate this possibility, biofilms of Sporomusa ovata, which are effective in acetate electrosynthesis, were grown on a range of cathode materials and acetate production was monitored over time. Modifications of carbon cloth that resulted in a positive-charge enhanced microbial electrosynthesis. Functionalization with chitosan or cyanuric chloride increased acetate production rates 6–7 fold and modification with 3-aminopropyltriethoxysilane ...


Engineering Geobacter Sulferreducens To Produce A Highly Cohesive Conductive Matrix With Enhanced Capacity For Current Production, Ching Leang, Nikhil S. Malvankar, Ashley E. Franks, Kelly P. Nevin, Derek R. Lovley Jan 2013

Engineering Geobacter Sulferreducens To Produce A Highly Cohesive Conductive Matrix With Enhanced Capacity For Current Production, Ching Leang, Nikhil S. Malvankar, Ashley E. Franks, Kelly P. Nevin, Derek R. Lovley

Derek Lovley

The conductive biofilms of Geobacter sulfurreducens have potential applications in renewable energy, bioremediation, and bioelectronics. In an attempt to alter biofilm properties, genes encoding proteins with a PilZ domain were deleted from the G. sulfurreducens genome. A strain, in which the gene GSU1240 was deleted, designated strain CL-1, formed biofilms much more effectively than did the wildtype strain. Increased production of pili and exopolysaccharide were associated with the enhanced biofilm production. When grown with an electrode as the electron acceptor CL-1 produced biofilms that were 6-fold more conductive than wild-type biofilms. The greater conductivity lowered the potential losses in microbial ...


A Lipid Membrane Intercalating Conjugated Oligoelectrolyte Enables Electrode Driven Succinate Production In Shewanella, Alexander W. Thomas, Logan E. Garner, Kelly P. Nevin, Trevor L. Woodard, Ashley E. Franks, Derek R. Lovley, James J. Sumner, Christian J. Sund, Guillermo C. Bazan Dec 2012

A Lipid Membrane Intercalating Conjugated Oligoelectrolyte Enables Electrode Driven Succinate Production In Shewanella, Alexander W. Thomas, Logan E. Garner, Kelly P. Nevin, Trevor L. Woodard, Ashley E. Franks, Derek R. Lovley, James J. Sumner, Christian J. Sund, Guillermo C. Bazan

Derek Lovley

An amphiphilic conjugated oligoelectrolyte (COE) that spontaneously intercalates into lipid membranes enables Shewanella oneidensis to use a graphite electrode as the sole electron donor for succinate production. Current consumed in a poised electrochemical system by Shewanella with micromolar concentrations of COE correlates well with the succinate produced via fumarate reduction as determined by HPLC analysis. Confocal microscopy confirms incorporation of the COE into the microbes on the electrode surface. This work presents a unique strategy to induce favorable bioelectronics interactions for the production of reduced microbial metabolites.


Molecular Analysis Of The In Situ Growth Rate Of Subsurface Geobacter Species, Dawn E. Holmes, Ludovic Giloteaux, Melissa Barlett, Milind A. Chavan, Jessica A. Smith, Kenneth H. Williams, Michael Wilkins, Philip Long, Derek Lovley Dec 2012

Molecular Analysis Of The In Situ Growth Rate Of Subsurface Geobacter Species, Dawn E. Holmes, Ludovic Giloteaux, Melissa Barlett, Milind A. Chavan, Jessica A. Smith, Kenneth H. Williams, Michael Wilkins, Philip Long, Derek Lovley

Derek Lovley

Molecular tools that can provide an estimate of the in situ growth rate of Geobacter species could improve understanding of dissimilatory metal reduction in a diversity of environments. Whole genome microarray analyses of the subsurface isolate, Geobacter uraniireducens, grown under a variety of conditions identified a number of genes that are differentially expressed at different specific growth rates. Expression of two genes encoding ribosomal proteins, rpsC and rplL, were further evaluated with quantitative reverse transcription PCR (qRT-PCR) in cells with doubling times ranging from 6.56 h to 89.28 h. Transcript abundance of rpsC correlated best (r2= 0.90 ...


The Rnf Complex Of Clostridium Ljungdahlii Is A Proton-Translocating Ferredoxin: Nad+ Oxidoreductase Essential For Autotrophic Growth, Pier-Luc Tremblay, Tian Zhang, Shabir A. Dar, Ching Leang, Derek Lovley Dec 2012

The Rnf Complex Of Clostridium Ljungdahlii Is A Proton-Translocating Ferredoxin: Nad+ Oxidoreductase Essential For Autotrophic Growth, Pier-Luc Tremblay, Tian Zhang, Shabir A. Dar, Ching Leang, Derek Lovley

Derek Lovley

It has been predicted that the Rnf complex of Clostridium ljungdahlii is a proton-translocating ferredoxin:NAD+ oxidoreductase which contributes to ATP synthesis by an H+-translocating ATPase under both autotrophic and heterotrophic growth conditions. The recent development of methods for genetic manipulation of C. ljungdahlii made it possible to evaluate the possible role of the Rnf complex in energy conservation. Disruption of the C. ljungdahlii rnf operon inhibited autotrophic growth. ATP synthesis, proton gradient, membrane potential, and proton motive force collapsed in the Rnf-deficient mutant with H2 as the electron source and CO2 as the electron acceptor. Heterotrophic growth was ...


The Genome Of Pelobacter Carbinolicus Reveals Surprising Metabolic Capabilities And Physiological Features, Muktak Aklujkar, Shelley A. Haveman, Raymond Didonato, Olga Chertkov, Cliff S. Han, Miriam L. Land, Peter Brown, Derek Lovley Dec 2012

The Genome Of Pelobacter Carbinolicus Reveals Surprising Metabolic Capabilities And Physiological Features, Muktak Aklujkar, Shelley A. Haveman, Raymond Didonato, Olga Chertkov, Cliff S. Han, Miriam L. Land, Peter Brown, Derek Lovley

Derek Lovley

BackgroundThe bacterium Pelobacter carbinolicus is able to grow by fermentation, syntrophic hydrogen/formate transfer, or electron transfer to sulfur from short-chain alcohols, hydrogen or formate; it does not oxidize acetate and is not known to ferment any sugars or grow autotrophically. The genome of P. carbinolicus was sequenced in order to understand its metabolic capabilities and physiological features in comparison with its relatives, acetate-oxidizing Geobacter species.ResultsPathways were predicted for catabolism of known substrates: 2,3-butanediol, acetoin, glycerol, 1,2-ethanediol, ethanolamine, choline and ethanol. Multiple isozymes of 2,3-butanediol dehydrogenase, ATP synthase and [FeFe]-hydrogenase were differentiated and assigned roles ...


Improved Cathode Materials For Microbial Electrosynthesis, Tian Zhang, Huarong Nie, Timothy S. Bain, Haiyun Lu, Mengmeng Cui, Oona L. Snoeyenbos-West, Ashley E. Franks, Kelly P. Nevin, Thomas P. Russell, Derek Lovley Nov 2012

Improved Cathode Materials For Microbial Electrosynthesis, Tian Zhang, Huarong Nie, Timothy S. Bain, Haiyun Lu, Mengmeng Cui, Oona L. Snoeyenbos-West, Ashley E. Franks, Kelly P. Nevin, Thomas P. Russell, Derek Lovley

Derek Lovley

Microbial electrosynthesis is a promising strategy for the microbial conversion of carbon dioxide to transportation fuels and other organic commodities, but optimization of this process is required for commercialization. Cathodes which enhance electrode–microbe electron transfer might improve rates of product formation. To evaluate this possibility, biofilms of Sporomusa ovata, which are effective in acetate electrosynthesis, were grown on a range of cathode materials and acetate production was monitored over time. Modifications of carbon cloth that resulted in a positive-charge enhanced microbial electrosynthesis. Functionalization with chitosan or cyanuric chloride increased acetate production rates 6–7 fold and modification with 3-aminopropyltriethoxysilane ...


Interspecies Electron Transfer Via H2 And Formate Rather Than Direct Electrical Connections In Co-Cultures Of Pelobacter Carbinolicus And Geobacter Sulfurreducens, Amelia-Elena Rotaru, Pravin M. Shrestha, Fanghua Liu, Toshiyuki Ueki, Kelly Nevin, Zarath M. Summers, Derek Lovley Oct 2012

Interspecies Electron Transfer Via H2 And Formate Rather Than Direct Electrical Connections In Co-Cultures Of Pelobacter Carbinolicus And Geobacter Sulfurreducens, Amelia-Elena Rotaru, Pravin M. Shrestha, Fanghua Liu, Toshiyuki Ueki, Kelly Nevin, Zarath M. Summers, Derek Lovley

Derek Lovley

Direct interspecies electron transfer (DIET) is an alternative to interspecies H2/formate transfer as a mechanism for microbial species to cooperatively exchange electrons during syntrophic metabolism. To understand what specific properties contribute to DIET, studies were conducted with Pelobacter carbinolicus, a close relative of Geobacter metallireducens, which is capable of DIET. P. carbinolicus grew in co-culture with Geobacter sulfurreducens with ethanol as electron donor and fumarate as electron acceptor, conditions under which G. sulfurreducens formed direct electrical connections with G. metallireducens. In contrast to the cell aggregation associated with DIET, P. carbinolicus and G. sulfurreducens did not aggregate. Attempts to ...


Comparative Genomic Analysis Of Geobacter Sulfurreducens Kn400, A Strain With Enhanced Capacity For Extracellular Electron Transfer And Electricity Production, Jessica E. Butler, Nelson D. Young, Muktak Aklujkar, Derek Lovley Sep 2012

Comparative Genomic Analysis Of Geobacter Sulfurreducens Kn400, A Strain With Enhanced Capacity For Extracellular Electron Transfer And Electricity Production, Jessica E. Butler, Nelson D. Young, Muktak Aklujkar, Derek Lovley

Derek Lovley

Background A new strain of Geobacter sulfurreducens, strain KN400, produces more electrical current in microbial fuel cells and reduces insoluble Fe(III) oxides much faster than the wildtype strain, PCA. The genome of KN400 was compared to wildtype with the goal of discovering how the network for extracellular electron transfer has changed and how these two strains evolved. Results Both genomes were re-annotated, resulting in 14 fewer genes (net) in the PCA genome; 28 fewer (net) in the KN400 genome; and ca. 400 gene start and stop sites moved. 96% of genes in KN400 had clear orthologs with conserved synteny ...


Promoting Direct Interspecies Electron Transfer With Activated Carbon, Derek Lovley, Fanghua Liu, Amelia-Elena Rotaru, Pravin M. Shrestha, Nikhil S. Malvankar, Kelly P. Nevin Jul 2012

Promoting Direct Interspecies Electron Transfer With Activated Carbon, Derek Lovley, Fanghua Liu, Amelia-Elena Rotaru, Pravin M. Shrestha, Nikhil S. Malvankar, Kelly P. Nevin

Derek Lovley

Granular activated carbon (GAC) is added to methanogenic digesters to enhance conversion of wastes to methane, but the mechanism(s) for GAC's stimulatory effect are poorly understood. GAC has high electrical conductivity and thus it was hypothesized that one mechanism for GAC stimulation of methanogenesis might be to facilitate direct interspecies electron transfer (DIET) between bacteria and methanogens. Metabolism was substantially accelerated when GAC was added to co-cultures of Geobacter metallireducens and Geobacter sulfurreducens grown under conditions previously shown to require DIET. Cells were attached to GAC, but did not aggregate as they do when making biological electrical connections ...


Lack Of Cytochrome Involvement In Long-Range Electron Transport Through Conductive Biofilms And Nanowires Of Geobacter Sulfurreducens, Nikhil S. Malvankar, Mark T. Tuominen, Derek Lovley Jul 2012

Lack Of Cytochrome Involvement In Long-Range Electron Transport Through Conductive Biofilms And Nanowires Of Geobacter Sulfurreducens, Nikhil S. Malvankar, Mark T. Tuominen, Derek Lovley

Derek Lovley

Two competing models for long-range electron transport through the conductive biofilms and nanowires of Geobacter sulfurreducens exist. In one model electrons are transported via pili that possess delocalized electronic states to function as protein wires with metallic-like conductivity. In the other model electrons are transported by more traditional electron transfer via electron hopping/tunneling between the c-type cytochromes in G. sulfurreducens biofilms and pili. The cytochrome hypothesis was further examined. Quantifying c-type cytochromes in G. sulfurreducens biofilms and pili indicated that there are insufficient cytochromes to account for electron transport through the bulk of the biofilm or pili and demonstrated ...


Role Of The Nife Hydrogenase Hya In Oxidative Stress Defense In Geobacter Sulfurreducens, Pier-Luc Tremblay, Derek Lovley May 2012

Role Of The Nife Hydrogenase Hya In Oxidative Stress Defense In Geobacter Sulfurreducens, Pier-Luc Tremblay, Derek Lovley

Derek Lovley

Geobacter sulfurreducens, an Fe(III)-reducing deltaproteobacterium found in anoxic subsurface environments, contains 4 NiFe hydrogenases. Hyb, a periplasmically oriented membrane-bound NiFe hydrogenase, is essential for hydrogen-dependent growth. The functions of the three other hydrogenases are unknown. We show here that the other periplasmically oriented membrane-bound NiFe hydrogenase, Hya, is necessary for growth after exposure to oxidative stress when hydrogen or a highly limiting concentration of acetate is the electron source. The beneficial impact of Hya on growth was dependent on the presence of H(2) in the atmosphere. Moreover, the Hya-deficient strain was more sensitive to the presence of ...


Microbial Functional Gene Diversity With A Shift Of Subsurface Redox Conditions During In Situ Uranium Reduction, Yuting Liang, Joy D. Van Nostrand, Lucie A. N′Guessan, Aaron D. Peacock, Ye Deng, Philip E. Long, Tom C. Resch, Liyou Wu, Zhili He, Guanghe Li, Terry C. Hazen, Derek Lovley, Jizhong Zhoua Apr 2012

Microbial Functional Gene Diversity With A Shift Of Subsurface Redox Conditions During In Situ Uranium Reduction, Yuting Liang, Joy D. Van Nostrand, Lucie A. N′Guessan, Aaron D. Peacock, Ye Deng, Philip E. Long, Tom C. Resch, Liyou Wu, Zhili He, Guanghe Li, Terry C. Hazen, Derek Lovley, Jizhong Zhoua

Derek Lovley

To better understand the microbial functional diversity changes with subsurface redox conditions during in situ uranium bioremediation, key functional genes were studied with GeoChip, a comprehensive functional gene microarray, in field experiments at a uranium mill tailings remedial action (UMTRA) site (Rifle, CO). The results indicated that functional microbial communities altered with a shift in the dominant metabolic process, as documented by hierarchical cluster and ordination analyses of all detected functional genes. The abundance of dsrAB genes (dissimilatory sulfite reductase genes) and methane generation-related mcr genes (methyl coenzyme M reductase coding genes) increased when redox conditions shifted from Fe-reducing to ...


Integrative Analysis Of Geobacter Spp. And Sulfate-Reducing Bacteria During Uranium Bioremediation, M. Barlett, K. Zhuang, R. Mahadevan, Derek Lovley Mar 2012

Integrative Analysis Of Geobacter Spp. And Sulfate-Reducing Bacteria During Uranium Bioremediation, M. Barlett, K. Zhuang, R. Mahadevan, Derek Lovley

Derek Lovley

Enhancing microbial U(VI) reduction with the addition of organic electron donors is a promising strategy for immobilizing uranium in contaminated groundwaters, but has yet to be optimized because of a poor understanding of the factors controlling the growth of various microbial communities during bioremediation. In previous field trials in which acetate was added to the subsurface, there were two distinct phases: an initial phase in which acetate-oxidizing, U(VI)-reducing Geobacter predominated and U(VI) was effectively reduced and a second phase in which acetate-oxidizing sulfate reducing bacteria (SRB) predominated and U(VI) reduction was poor. The interaction of ...


Comment On “On Electrical Conductivity Of Microbial Nanowires And Biofilms” By S. M. Strycharz-Glaven, R. M. Snider, A. Guiseppi-Elie And L. M. Tender, Energy Environ. Sci., 2011, 4, 4366, Nikhil S. Malvankar, Mark T. Tuominen, Derek Lovley Feb 2012

Comment On “On Electrical Conductivity Of Microbial Nanowires And Biofilms” By S. M. Strycharz-Glaven, R. M. Snider, A. Guiseppi-Elie And L. M. Tender, Energy Environ. Sci., 2011, 4, 4366, Nikhil S. Malvankar, Mark T. Tuominen, Derek Lovley

Derek Lovley

A paper published in Energy and Environmental Science by Strycharz-Glaven et al. suggests that electron transport along the pili and through the conductive biofilms of Geobacter sulfurreducens proceeds via electron superexchange rather than metallic-like conductivity. Multiple lines of evidence disprove the superexchange hypothesis, but are consistent with metallic-like conductivity.


Biofilm Conductivity Is A Decisive Variable For High-Current-Density Geobacter Sulfurreducens Microbial Fuel Cells, Nikhil S. Malvankar, Mark T. Tuominen, Derek Lovley Jan 2012

Biofilm Conductivity Is A Decisive Variable For High-Current-Density Geobacter Sulfurreducens Microbial Fuel Cells, Nikhil S. Malvankar, Mark T. Tuominen, Derek Lovley

Derek Lovley

Current outputs of microbial fuel cells (MFCs) are too low for most perceived practical applications. Most efforts for further optimization have focused on modifications of fuel cell architecture or electrode materials, with little investigation into the properties of microorganisms that are most essential for maximal current production. Geobacter sulfurreducens produces the highest current densities of any known pure culture; is closely related to the Geobacter species that often predominate in anode biofilms harvesting electricity from organic wastes; and produces highly conductive anode biofilms. Comparison of biofilm conductivities and current production in different strains of G. sulfurreducens revealed a direct correlation ...


Live Wires: Direct Extracellular Electron Exchange For Bioenergy And The Bioremediation Of Energy-Related Contamination, Derek Lovley Oct 2011

Live Wires: Direct Extracellular Electron Exchange For Bioenergy And The Bioremediation Of Energy-Related Contamination, Derek Lovley

Derek Lovley

Microorganisms that can form direct electrical connections with insoluble minerals, electrodes, or other microorganisms can play an important role in some traditional as well as novel bioenergy strategies and can be helpful in the remediation of environmental contamination resulting from the use of more traditional energy sources. The surprising discovery that microorganisms in the genus Geobacter are capable of forming highly conductive networks of filaments that transfer electrons along their length with organic metallic-like conductivity, rather than traditional molecule to molecule electron exchange, provides an explanation for the ability of Geobacter species to grow in subsurface environments with insoluble Fe ...


Molecular Analysis Of The Metabolic Rates Of Discrete Subsurface Populations Of Sulfate Reducers, Marzia Miletto, Kenneth H. Williams, A. Lucie N'Guessan, Derek Lovley Oct 2011

Molecular Analysis Of The Metabolic Rates Of Discrete Subsurface Populations Of Sulfate Reducers, Marzia Miletto, Kenneth H. Williams, A. Lucie N'Guessan, Derek Lovley

Derek Lovley

Elucidating the in situ metabolic activity of phylogenetically diverse populations of sulfate-reducing microorganisms that populate anoxic sedimentary environments is key to understanding subsurface ecology. Previous pure culture studies have demonstrated that the transcript abundance of dissimilatory (bi)sulfite reductase genes is correlated with the sulfate-reducing activity of individual cells. To evaluate whether expression of these genes was diagnostic for subsurface communities, dissimilatory (bi)sulfite reductase gene transcript abundance in phylogenetically distinct sulfate-reducing populations was quantified during a field experiment in which acetate was added to uranium-contaminated groundwater. Analysis of dsrAB sequences prior to the addition of acetate indicated that Desulfobacteraceae ...


Anaerobic Oxidation Of Benzene By The Hyperthermophilic Archaeon Ferroglobus Placidus, Derek Lovley, Dawn E. Holmes, Carla Risso, Jessica A. Smith Aug 2011

Anaerobic Oxidation Of Benzene By The Hyperthermophilic Archaeon Ferroglobus Placidus, Derek Lovley, Dawn E. Holmes, Carla Risso, Jessica A. Smith

Derek Lovley

Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [(14)C]benzene to [(14)C]carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe ...


Potential For Direct Interspecies Electron Transfer In Methanogenic Wastewater Digester Aggregates, Masahiko Morita, Nikhil S. Malvankar, Ashley E. Franks, Zarath M. Summers, Ludovic Giloteaux, Amelia E. Rotaru, Camelia Rotaru, Derek Lovley Aug 2011

Potential For Direct Interspecies Electron Transfer In Methanogenic Wastewater Digester Aggregates, Masahiko Morita, Nikhil S. Malvankar, Ashley E. Franks, Zarath M. Summers, Ludovic Giloteaux, Amelia E. Rotaru, Camelia Rotaru, Derek Lovley

Derek Lovley

Mechanisms for electron transfer within microbial aggregates derived from an upflow anaerobic sludge blanket reactor converting brewery waste to methane were investigated in order to better understand the function of methanogenic consortia. The aggregates were electrically conductive, with conductivities 3-fold higher than the conductivities previously reported for dual-species aggregates of Geobacter species in which the two species appeared to exchange electrons via interspecies electron transfer. The temperature dependence response of the aggregate conductance was characteristic of the organic metallic-like conductance previously described for the conductive pili of Geobacter sulfurreducens and was inconsistent with electron conduction through minerals. Studies in which ...


Development Of A Biomarker For Geobacter Activity And Strain Composition; Proteogenomic Analysis Of The Citrate Synthase Protein During Bioremediation Of U(Vi), Michael J. Wilkins, Stephen J. Callister, Marzia Miletto, Kenneth H. Williams, Carrie D. Nicora, Derek Lovley, Philip E. Long, Mary S. Lipton Dec 2010

Development Of A Biomarker For Geobacter Activity And Strain Composition; Proteogenomic Analysis Of The Citrate Synthase Protein During Bioremediation Of U(Vi), Michael J. Wilkins, Stephen J. Callister, Marzia Miletto, Kenneth H. Williams, Carrie D. Nicora, Derek Lovley, Philip E. Long, Mary S. Lipton

Derek Lovley

Monitoring the activity of target microorganisms during stimulated bioremediation is a key problem for the development of effective remediation strategies. At the US Department of Energy's Integrated Field Research Challenge (IFRC) site in Rifle, CO, the stimulation of Geobacter growth and activity via subsurface acetate addition leads to precipitation of U(VI) from groundwater as U(IV). Citrate synthase (gltA) is a key enzyme in Geobacter central metabolism that controls flux into the TCA cycle. Here, we utilize shotgun proteomic methods to demonstrate that the measurement of gltA peptides can be used to track Geobacter activity and strain evolution ...


Application Of Cyclic Voltammetry To Investigate Enhanced Catalytic Current Generation By Biofilm-Modified Anodes Of Geobacter Sulfurreducens Strain Dl1 Vs. Variant Strain Kn400, Sarah M. Strycharz, Anthony P. Malanoski, Rachel M. Snider, Hana Yi, Derek Lovley, Leonard M. Tender Dec 2010

Application Of Cyclic Voltammetry To Investigate Enhanced Catalytic Current Generation By Biofilm-Modified Anodes Of Geobacter Sulfurreducens Strain Dl1 Vs. Variant Strain Kn400, Sarah M. Strycharz, Anthony P. Malanoski, Rachel M. Snider, Hana Yi, Derek Lovley, Leonard M. Tender

Derek Lovley

A biofilm of Geobacter sulfurreducens will grow on an anode surface and catalyze the generation of an electrical current by oxidizing acetate and utilizing the anode as its metabolic terminal electron acceptor. Here we report qualitative analysis of cyclic voltammetry of anodes modified with biofilms of G. sulfurreducens strains DL1 and KN400 to predict possible rate-limiting steps in current generation. Strain KN400 generates approximately 2 to 8-fold greater current than strain DL1 depending upon the electrode material, enabling comparative electrochemical analysis to study the mechanism of current generation. This analysis is based on our recently reported electrochemical model for biofilm-catalyzed ...


Bioinformatic Analysis Of Gene Regulation In The Metal-Reducing Bacteria Family, Derek Lovley, Julia Krushkal, Ronald M. Adkins, Yanhua Qu, Jeanette Peeples, Sreedhar Sontineni, Ching Leang, Peter Brown, Nelson D. Young, Toshiyuki Ueki, Katy Juarez Dec 2010

Bioinformatic Analysis Of Gene Regulation In The Metal-Reducing Bacteria Family, Derek Lovley, Julia Krushkal, Ronald M. Adkins, Yanhua Qu, Jeanette Peeples, Sreedhar Sontineni, Ching Leang, Peter Brown, Nelson D. Young, Toshiyuki Ueki, Katy Juarez

Derek Lovley

Knowledge of how structural genome differences among microorganisms lead to variation in gene regulation is fundamentally important for our understanding of the functioning of gene regulatory pathways and their individual components. This knowledge is also necessary for our better understanding of the genomic changes leading to adaptation to diverse and changing environments. Our research focuses on Geobacteraceae, a metal-reducing family of delta-Proteobacteria, which are capable of harvesting electricity from organic matter and environmental bioremediation of organic and metal pollutants. We are investigating molecular mechanisms which allow these species to adapt and regulate their responses to environmental stimuli, which result in ...


Novel Regulatory Cascades Controlling Expression Of Nitrogen Fixation Genes, Toshiyuki Ueki, Derek Lovley Jul 2010

Novel Regulatory Cascades Controlling Expression Of Nitrogen Fixation Genes, Toshiyuki Ueki, Derek Lovley

Derek Lovley

Geobacter species often play an important role in bioremediation of environments contaminated with metals or organics and show promise for harvesting electricity from waste organic matter in microbial fuel cells. The ability of Geobacter species to fix atmospheric nitrogen is an important metabolic feature for these applications. We identified novel regulatory cascades controlling nitrogen-fixation gene expression in Geobacter sulfurreducens. Unlike the regulatory mechanisms known in other nitrogen-fixing microorganisms, nitrogen-fixation gene regulation in G. sulfurreducens is controlled by two two-component His-Asp phosphorelay systems. One of these systems appears to be the master regulatory system that activates transcription of the majority of ...


Electrodic Voltages Accompanying Stimulated Bioremediation Of A Uranium-Contaminated Aquifer, Kenneth H. Williams, A. Lucie N'Guessan, Jennifer Druhan, Philip E. Long, Susan S. Hubbard, Derek Lovley, Jillian F. Banfield Jun 2010

Electrodic Voltages Accompanying Stimulated Bioremediation Of A Uranium-Contaminated Aquifer, Kenneth H. Williams, A. Lucie N'Guessan, Jennifer Druhan, Philip E. Long, Susan S. Hubbard, Derek Lovley, Jillian F. Banfield

Derek Lovley

The inability to track the products of subsurface microbial activity during stimulated bioremediation has limited its implementation. We used spatiotemporal changes in electrodic potentials (EP) to track the onset and persistence of stimulated sulfate-reducing bacteria in a uranium-contaminated aquifer undergoing acetate amendment. Following acetate injection, anomalous voltages approaching −900 mV were measured between copper electrodes within the aquifer sediments and a single reference electrode at the ground surface. Onset of EP anomalies correlated in time with both the accumulation of dissolved sulfide and the removal of uranium from groundwater. The anomalies persisted for 45 days after halting acetate injection. Current-voltage ...


Role Of Geobacter Sulfurreducens Outer-Surface C-Type Cytochromes In Reduction Of Soil Humic Acid And Anthraquinone-2,6-Disulfonate, James W. Voordeckers, Byoung-Chan Kim, Mounir Izallalen, Derek Lovley Apr 2010

Role Of Geobacter Sulfurreducens Outer-Surface C-Type Cytochromes In Reduction Of Soil Humic Acid And Anthraquinone-2,6-Disulfonate, James W. Voordeckers, Byoung-Chan Kim, Mounir Izallalen, Derek Lovley

Derek Lovley

Deleting individual genes for outer surface c-type cytochromes in Geobacter sulfurreducens partially inhibited the reduction of humic substances and anthraquinone-2,6,-disulfonate. Complete inhibition was obtained only when five of these genes were simultaneously deleted, suggesting that diverse outer surface cytochromes can contribute to the reduction of humic substances and other extracellular quinones.


Microbial Electrosynthesis:Feeding Microbes Electricity To Convert Carbon Dioxide And Water To Multi Carbon Extracellular Organic Compounds, Derek Lovley, Kelly P. Nevin, Trevor L. Woodward, Ashley E. Franks, Zarath M. Summers Jan 2010

Microbial Electrosynthesis:Feeding Microbes Electricity To Convert Carbon Dioxide And Water To Multi Carbon Extracellular Organic Compounds, Derek Lovley, Kelly P. Nevin, Trevor L. Woodward, Ashley E. Franks, Zarath M. Summers

Derek Lovley

The possibility of providing the acetogenic microorganism Sporomusa ovata with electrons delivered directly to the cells with a graphite electrode for the reduction of carbon dioxide to organic compounds was investigated. Biofilms of S. ovata growing on graphite cathode surfaces consumed electrons with the reduction of carbon dioxide to acetate and small amounts of 2-oxobutyrate. Electrons appearing in these products accounted for over 85% of the electrons consumed. These results demonstrate that microbial production of multicarbon organic compounds from carbon dioxide and water with electricity as the energy source is feasible. Importance Reducing carbon dioxide to multicarbon organic chemicals and ...