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Full-Text Articles in Life Sciences
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
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) with specific growth …
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
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 hindered in …
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
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 according to their structural properties and …
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
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 gave rates …
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
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 in …
Promoting Direct Interspecies Electron Transfer With Activated Carbon, Derek Lovley, Fanghua Liu, Amelia-Elena Rotaru, Pravin M. Shrestha, Nikhil S. Malvankar, Kelly P. Nevin
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 between cells. …
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
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 that …
Role Of The Nife Hydrogenase Hya In Oxidative Stress Defense In Geobacter Sulfurreducens, Pier-Luc Tremblay, Derek Lovley
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 superoxide or hydrogen …
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
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
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 Geobacter and SRB was investigated …
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
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
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 …