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bacterial recognition of silicon nanowire arrays.understanding how living cells interact with nanostructures is integral to a better understanding of the fundamental principles of biology and the development of next-generation biomedical/bioenergy devices. recent studies have demonstrated that mammalian cells can recognize nanoscale topographies and respond to these structures. from this perspective, there is a growing recognition that nanostructures, along with their specific physicochemical properties, can also be used to regulate the respon ...201323682751
proof of principle for an engineered microbial biosensor based on shewanella oneidensis outer membrane protein complexes.shewanella oneidensis is known for its ability to respire on extracellular electron acceptors. the spectrum of these acceptors also includes anode surfaces. based on this activity, a versatile s. oneidensis based biosensor strain was constructed in which electricity production can be modulated. construction started with the identification of a usable rate-limiting step of electron transfer to an anode. thereafter, the sensor strain was genetically engineered to produce a protein complex consisti ...201323584391
rate enhancement of bacterial extracellular electron transport involves bound flavin semiquinones.extracellular redox-active compounds, flavins and other quinones, have been hypothesized to play a major role in the delivery of electrons from cellular metabolic systems to extracellular insoluble substrates by a diffusion-based shuttling two-electron-transfer mechanism. here we show that flavin molecules secreted by shewanella oneidensis mr-1 enhance the ability of its outer-membrane c-type cytochromes (om c-cyts) to transport electrons as redox cofactors, but not free-form flavins. whole-cell ...201323576738
role of electricity production in the anaerobic decolorization of dye mixture by exoelectrogenic bacterium shewanella oneidensis mr-1.this study investigated the anaerobic decolorization of the dye mixture containing methyl orange (mo) and naphthol green b (ngb) by shewanella oneidensis mr-1. s. oneidensis mr-1 showed a strong ability to decolorize the dye mixture. mo was easier to get the electrons and inhibited the reduction of ngb, despite of its lower redox potential than ngb. the mtr respiratory pathway played an important role in this process. meantime, addition of extracellular electron shuttles accelerated the decolori ...201323567679
phenothiazine derivative-accelerated microbial extracellular electron transfer in bioelectrochemical system.in bioelectrochemical system (bes) the extracellular electron transfer (eet) from bacteria to anode electrode is recognized as a crucial step that governs the anodic reaction efficiency. here, we report a novel approach to substantially enhance the microbial eet by immobilization of a small active phenothiazine derivative, methylene blue, on electrode surface. a comparison of the currents generated by shewanella oneidensis mr-1 and its mutants as well as the electrochemical analytical results re ...201323563590
electron acceptor dependence of electron shuttle secretion and extracellular electron transfer by shewanella oneidensis mr-1.shewanella oneidensis mr-1 is an extensively studied dissimilatory metal-reducing bacterium with a great potential for bioremediation and electricity generation. it secretes flavins as electron shuttles which play an important role in extracellular electron transfer. however, the influence of various environmental factors on the secretion of flavins is largely unknown. here, the effects of electron acceptors, including fumarate, ferrihydrite, fe(iii)-nitrilotriacetic acid (nta), nitrate and trim ...201323558182
accelerated removal of sudan dye by shewanella oneidensis mr-1 in the presence of quinones and humic acids.although there have been many studies on bacterial removal of soluble azo dyes, much less information is available for biological treatment of water-insoluble azo dyes. the few bacterial species capable of removing sudan dye generally require a long time to remove low concentrations of insoluble dye particles. the present work examined the efficient removal of sudan i by shewanella oneidensis mr-1 in the presence of redox mediator. it was found that the microbially reduced anthraquinone-2,6-disu ...201323539152
rapid electron exchange between surface-exposed bacterial cytochromes and fe(iii) minerals.the mineral-respiring bacterium shewanella oneidensis uses a protein complex, mtrcab, composed of two decaheme cytochromes, mtrc and mtra, brought together inside a transmembrane porin, mtrb, to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. a proteoliposome system containing a pool of internalized electron carriers was used to investigate how the topology of the mtrcab complex relates to its ability to transport electrons across a lipid bilayer t ...201323538304
enhanced performance of hexavalent chromium reducing cathodes in the presence of shewanella oneidensis mr-1 and lactate.biocathodes for the reduction of the highly toxic hexavalent chromium (cr(vi)) were investigated using shewanella oneidensis mr-1 (mr-1) as a biocatalyst and performance was assessed in terms of current production and cr(vi) reduction. potentiostatically controlled experiments (-500 mv vs ag/agcl) showed that a mediatorless mr-1 biocathode started up under aerated conditions in the presence of lactate, received 5.5 and 1.7 times more electrons for cr(vi) reduction over a 4 h operating period tha ...201323517384
diffusion in biofilms respiring on electrodes.the goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (d(e)) in biofilms respiring on electrodes. two model electrochemically active biofilms, geobacter sulfurreducens pca and shewanella oneidensis mr-1, were investigated. a novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (pfg-nmr) techniques was used. pfg-nmr allowed noninvasive, nondestru ...201323420623
crp-dependent cytochrome bd oxidase confers nitrite resistance to shewanella oneidensis.shewanella oneidensis is able to respire on a variety of organic and inorganic substrates, including nitrate and nitrite. conversion of nitrate to nitrite and nitrite to ammonium is catalysed by periplasmic nitrate and nitrite reductases (nap and nrf) respectively. global regulator crp (cyclic amp receptor protein) is essential for growth of s. oneidensis on both nitrate and nitrite. in this study, we discovered that crp mutants are not only severely deficient in nitrate or nitrite respiration, ...201323414111
electrospun carbon nanofibers from polyacrylonitrile blended with activated or graphitized carbonaceous materials for improving anodic bioelectrocatalysis.the electrospun carbon nanofibers obtained from polyacrylonitrile (pan) and pan blends with either activated carbon (pan-ac) or graphite (pan-gr) were tested as anodes using shewanella oneidensis mr-1. extensive physico-chemical and electrochemical characterization confirmed their formation, their fibrous and porous nature, and their suitability as electrodes. n2 adsorption measurements revealed high specific surface area (229.8, 415.8 and 485.2m(2) g(-1)) and porosity (0.142, 0.202 and 0.239cm( ...201323399497
influence of outer membrane c-type cytochromes on particle size and activity of extracellular nanoparticles produced by shewanella oneidensis.the metal-reducing bacterium shewanella oneidensis is capable of reducing various metal(loid)s and produces nanoparticles (nps) extracellularly, in which outer membrane c-type cytochromes (omcs) have been suggested to play important roles. the objective of this study was to investigate the influence of the omcs, that is, mtrc and omca, on the size and activity of the extracellular silver nps (agnps) and silver sulfide nps (ag(2)s nps) produced by s. oneidensis mr-1. we found that (i) the lack of ...201323381725
increase of riboflavin biosynthesis underlies enhancement of extracellular electron transfer of shewanella in alkaline microbial fuel cells.electrolyte ph tremendously affects the electricity output of microbial fuel cells. however, its underlying molecular mechanism remains elusive, in particular for shewanella oneidensis mr-1, one of the most widely adopted electrogenic microorganisms. herein, we found that mfcs were able to deliver a significant (but different) electricity output in a wide range of ph (from 6 to 10), with the maximum at ph=9 (alkaline), which delivers ∼1.5times' higher power output than that at ph=7 (neutral). fu ...201323353587
exoprotein production correlates with morphotype changes of nonmotile shewanella oneidensis mutants.we report a previously undescribed mechanism for the rugose morphotype in shewanella oneidensis, a research model for investigating redox transformations of environmental contaminants. bacteria may form smooth or rugose colonies on agar plates. in general, conversion from the smooth to rugose colony morphotype is attributed to increased production of exopolysaccharide (eps). in this work, we discovered that aflagellate s. oneidensis mutants grew into rugose colonies, whereas those with nonfuncti ...201323335418
concentration responses of toxicity sensor with shewanella oneidensis mr-1 growing in bioelectrochemical systems.bioelectrochemical systems (bess) provide an opportunity to detect biological toxicity of water samples. however, the concentration responses of toxins had not been investigated in detail. using formaldehyde as a toxic substance, the current responses were analyzed over a concentration range from 0.01% to 0.10% in a single chambered bes with 0mv (versus saturated calomel electrode) applied on the anode. the decay percentages of currents increased in proportion with the concentration of formaldeh ...201323333921
flavin electron shuttles dominate extracellular electron transfer by shewanella oneidensis.shewanella oneidensis strain mr-1 is widely studied for its ability to respire a diverse array of soluble and insoluble electron acceptors. the ability to breathe insoluble substrates is defined as extracellular electron transfer and can occur via direct contact or by electron shuttling in s. oneidensis. to determine the contribution of flavin electron shuttles in extracellular electron transfer, a transposon mutagenesis screen was performed with s. oneidensis to identify mutants unable to secre ...201323322638
single-cell imaging and spectroscopic analyses of cr(vi) reduction on the surface of bacterial cells.we investigate the single-cell reduction of toxic cr(vi) by the dissimilatory metal-reducing bacterium shewanella oneidensis mr-1 (mr-1), an important bioremediation process, using raman spectroscopy and scanning electron microscopy (sem) combined with energy-dispersive x-ray spectroscopy (edx). our experiments indicate that the toxic, highly soluble cr(vi) can be efficiently reduced to less toxic, nonsoluble cr(2)o(3) nanoparticles by mr-1. cr(2)o(3) is observed to emerge as nanoparticles adsor ...201323249294
patterned hydrophobic domains in the exopolymer matrix of shewanella oneidensis mr-1 biofilms.water-dispersible amphiphilic surface-engineered quantum dots (qds) were found to be strongly accumulated within discrete zones of the exopolymer network of shewanella oneidensis mr-1 biofilms, but not on the cell surfaces. these microdomains showed a patterned distribution in the exopolymer matrix, which led to a restricted diffusion of the amphiphilic nanoparticles.201323220957
genomic plasticity enables a secondary electron transport pathway in shewanella oneidensis.microbial dissimilatory iron reduction is an important biogeochemical process. it is physiologically challenging because iron occurs in soils and sediments in the form of insoluble minerals such as hematite or ferrihydrite. shewanella oneidensis mr-1 evolved an extended respiratory chain to the cell surface to reduce iron minerals. interestingly, the organism evolved a similar strategy for reduction of dimethyl sulfoxide (dmso), which is reduced at the cell surface as well. it has already been e ...201323220953
temporal expression-based analysis of metabolism.metabolic flux is frequently rerouted through cellular metabolism in response to dynamic changes in the intra- and extra-cellular environment. capturing the mechanisms underlying these metabolic transitions in quantitative and predictive models is a prominent challenge in systems biology. progress in this regard has been made by integrating high-throughput gene expression data into genome-scale stoichiometric models of metabolism. here, we extend previous approaches to perform a temporal express ...201223209390
power generation from a hybrid biological fuel cell in seawater.a hybrid biological fuel cell (hbfc) comprised of a microbial anode for lactate oxidation and an enzymatic cathode for oxygen reduction was constructed and then tested in a marine environment. shewanella oneidensis dsp-10 was cultivated in laboratory medium and then fixed on a carbon felt electrode via a silica sol-gel process in order to catalyze anodic fuel cell processes. the cathode electrocatalyst was composed of bilirubin oxidase, fixed to a carbon nanotube electrode using a heterobifuncti ...201323196242
recent advances in structural biology of peptide transporters.peptide transporters localized at brush-border membranes of intestinal and renal epithelial cells mediate the membrane transport of di- and tripeptides, and play important roles in protein absorption and the conservation of peptide-bound amino nitrogen. peptide-like drugs that show structural similarities to di- and tripeptides are also recognized by peptide transporters. the energy for transport of small peptides and peptide-like drugs is provided by the proton gradient across the cell membrane ...201223177989
the quest to achieve the detailed structural and functional characterization of cyma.shewanella oneidensis mr-1 is a sediment organism capable of dissimilatory reduction of insoluble metal compounds such as those of fe(ii) and mn(iv). this bacterium has been used as a model organism for potential applications in bioremediation of contaminated environments and in the production of energy in microbial fuel cells. the capacity of shewanella to perform extracellular reduction of metals is linked to the action of several multihaem cytochromes that may be periplasmic or can be associa ...201223176470
mind the gap: diversity and reactivity relationships among multihaem cytochromes of the mtra/dmse family.shewanella oneidensis mr-1 has the ability to use many external terminal electron acceptors during anaerobic respiration, such as dmso. the pathway that facilitates this electron transfer includes the decahaem cytochrome dmse, a paralogue of the mtra family of decahaem cytochromes. although both dmse and mtra are decahaem cytochromes implicated in the long-range electron transfer across a ~300 å (1 å=0.1 nm) wide periplasmic 'gap', mtra has been shown to be only 105 å in maximal length. in the p ...201223176466
development of a proteoliposome model to probe transmembrane electron-transfer reactions.the mineral-respiring bacterium shewanella oneidensis uses a protein complex, mtrcab, composed of two decahaem cytochromes brought together inside a transmembrane porin to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. a proteoliposome system has been developed that contains methyl viologen as an internalized electron carrier and valinomycin as a membrane-associated cation exchanger. these proteoliposomes can be used as a model system to investiga ...201223176464
the roles of cyma in support of the respiratory flexibility of shewanella oneidensis mr-1.shewanella species are isolated from the oxic/anoxic regions of seawater and aquatic sediments where redox conditions fluctuate in time and space. colonization of these environments is by virtue of flexible respiratory chains, many of which are notable for the ability to reduce extracellular substrates including the fe(iii) and mn(iv) contained in oxide and phyllosilicate minerals. shewanella oneidensis mr-1 serves as a model organism to consider the biochemical basis of this flexibility. in the ...201223176457
comparative c-type cytochrome expression analysis in shewanella oneidensis strain mr-1 and anaeromyxobacter dehalogenans strain 2cp-c grown with soluble and insoluble oxidized metal electron acceptors.the genomes of shewanella oneidensis strain mr-1 and anaeromyxobacter dehalogenans strain 2cp-c encode 40 and 69 putative c-type cytochrome genes respectively. deletion mutant and biochemical studies have assigned specific functions to a few c-type cytochromes involved in electron transfer to oxidized metals in s. oneidensis strain mr-1. although promising, the genetic approach is limited to gene deletions that produce a distinct phenotype and to an organism for which a genetic system is availab ...201223176455
analysis of structural mtrc models based on homology with the crystal structure of mtrf.the outer-membrane decahaem cytochrome mtrc is part of the transmembrane mtrcab complex required for mineral respiration by shewanella oneidensis. mtrc has significant sequence similarity to the paralogous decahaem cytochrome mtrf, which has been structurally solved through x-ray crystallography. this now allows for homology-based models of mtrc to be generated. the structure of these mtrc homology models contain ten bis-histidine-co-ordinated c-type haems arranged in a staggered cross through a ...201223176451
ferric iron enhances electricity generation by shewanella oneidensis mr-1 in mfcs.fe(iii) supplemented into microbial fuel cells (mfc) at initial start-up increased electricity generation by shewanella oneidensis mr-1. the maximum power density reached 158.1 mw/m(2) with 6 mm fe(iii), compared with 73.9 mw/m(2) without fe(iii). a significant increase in power output was observed when mfc with established biofilm in the absence of fe(iii) was supplemented with fe(iii) afterward. the cell biomass of the anode biofilm of mfcs operated in the presence of fe(iii) was higher than t ...201323127834
comparison of bacterial cells and amine-functionalized abiotic surfaces as support for pd nanoparticle synthesis.an increasing demand for catalytic pd nanoparticles has motivated the search for sustainable production methods. an innovative approach uses bacterial cells as support material for synthesizing pd nanoparticles by reduction of pd(ii) with e.g. hydrogen or formate. nevertheless, drawbacks of microbially supported pd catalysts are the low catalytic activity compared to conventional pd nanocatalysts and the possible poisoning of the catalyst surface by sulfur originating from bacterial proteins. a ...201323107967
mind the gap: cytochrome interactions reveal electron pathways across the periplasm of shewanella oneidensis mr-1.extracellular electron transfer is the key metabolic trait that enables some bacteria to play a significant role in the biogeochemical cycling of metals and in bioelectrochemical devices such as microbial fuel cells. in shewanella oneidensis mr-1, electrons generated in the cytoplasm by catabolic processes must cross the periplasmic space to reach terminal oxidoreductases found at the cell surface. lack of knowledge on how these electrons flow across the periplasmic space is one of the unresolve ...201323067389
decolorization and detoxification of a sulfonated triphenylmethane dye aniline blue by shewanella oneidensis mr-1 under anaerobic conditions.in this work, the extracellular decolorization of aniline blue, a sulfonated triphenylmethane dye, by shewanella oneidensis mr-1 was confirmed. s. oneidensis mr-1 showed a high capacity for decolorizing aniline blue even at a concentration of up to 1,000 mg/l under anaerobic conditions. maximum decolorization efficiency appeared at ph 7.0 and 30 °c. lactate was a better candidate of electron donor for the decolorization of aniline blue. the addition of nitrate, hydrous ferric oxide, or trimethyl ...201323053116
biological accumulation of tellurium nanorod structures via reduction of tellurite by shewanella oneidensis mr-1.the dissimilatory metal-reducing bacterium, shewanella oneidensis mr-1, reduced tellurite (te(iv), teo(3)(2-)) to elemental tellurium under anaerobic conditions resulting in the intracellular accumulation of needle shaped crystalline te(0) nanorods. fatty acid analyses showed that toxic te(iv) increased the unsaturated fatty acid composition of the lipid components of the cell membrane, implying a deconstruction of the integrity of the cellular membrane structure. the current results suggest tha ...201223026324
dynamic modeling of aerobic growth of shewanella oneidensis. predicting triauxic growth, flux distributions, and energy requirement for growth.a model-based analysis is conducted to investigate metabolism of shewanella oneidensis mr-1 strain in aerobic batch culture, which exhibits an intriguing growth pattern by sequentially consuming substrate (i.e., lactate) and by-products (i.e., pyruvate and acetate). a general protocol is presented for developing a detailed network-based dynamic model for s. oneidensis based on the lumped hybrid cybernetic model (l-hcm) framework. the l-hcm, although developed from only limited data, is shown to ...201323022551
preferential utilization of d-lactate by shewanella oneidensis.shewanella oneidensis couples oxidation of lactate to respiration of many substrates. here we report that llpr (l-lactate-positive regulator, so_3460) encodes a positive regulator of l-lactate utilization distinct from previously studied regulators. we also demonstrate d-lactate inhibition of l-lactate utilization in s. oneidensis, resulting in preferential utilization of the d isomer.201223001660
redox reactions of reduced flavin mononucleotide (fmn), riboflavin (rbf), and anthraquinone-2,6-disulfonate (aqds) with ferrihydrite and lepidocrocite.flavins are secreted by the dissimilatory iron-reducing bacterium shewanella and can function as endogenous electron transfer mediators. to assess the potential importance of flavins in fe(iii) bioreduction, we investigated the redox reaction kinetics of reduced flavin mononucleotide (i.e., fmnh(2)) and reduced riboflavin (i.e., rbfh(2)) with ferrihydrite and lepidocrocite. the organic reductants rapidly reduced and dissolved ferrihydrite and lepidocrocite in the ph range 4-8. the rate constant ...201222985396
improved microbial electrocatalysis with osmium polymer modified electrodes.using the well-known exoelectrogen shewanella oneidensis mr-1, an osmium redox polymer modified anode exhibited ca. 4-fold increase in current generation. additionally, a significant decrease in the start-up time for electrocatalysis was observed. the findings suggest that the inherent extracellular electron transfer capabilities of electrogens coupled with such polymers could enhance electrocatalysis.201222968325
the effect of the encapsulation of bacteria in redox phospholipid polymer hydrogels on electron transfer efficiency in living cell-based devices.development of living cell-based devices holds great promise in many biomedical and industrial applications. to increase our understanding of the process, we investigated the biological and electrochemical properties of a redox phospholipid polymer hydrogel containing an electron-generating bacteria (shewanella oneidensis mr-1). a water-soluble and amphiphilic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate-co-p-vinylphenylboronic acid-co-vinylferrocen ...201222938764
molecular and logic gate based on bacterial anaerobic respiration.enzyme coding genes that integrate information for anaerobic respiration in shewanella oneidensis mr-1 were used as input for constructing an and logic gate. the absence of one or both genes inhibited electrochemically-controlled anaerobic respiration, while wild type bacteria were capable of accepting electrons from an electrode for dmso reduction.201222932878
anomalies of the anaerobic tricarboxylic acid cycle in shewanella oneidensis revealed by tn-seq.the availability of increasingly inexpensive sequencing combined with an ever-expanding molecular biology toolbox has transported classical bacterial genetics into the 21st century. whole genome genetic fitness analysis using transposon mutagenesis combined with next-generation high-throughput sequencing (tn-seq) promises to revolutionize systems level analysis of microbial metabolism. tn-seq measures the frequency of actual members of a heterogeneous mutant pool undergoing purifying selection t ...201222925268
biofilm shows spatially stratified metabolic responses to contaminant exposure.biofilms are core to a range of biological processes, including the bioremediation of environmental contaminants. within a biofilm population, cells with diverse genotypes and phenotypes coexist, suggesting that distinct metabolic pathways may be expressed based on the local environmental conditions in a biofilm. however, metabolic responses to local environmental conditions in a metabolically active biofilm interacting with environmental contaminants have never been quantitatively elucidated. i ...201222925136
[creation of mutants of shewanella oneidensis mr-1 with increased reduction activity]. 201722880395
multistep hopping and extracellular charge transfer in microbial redox chains.dissimilatory metal-reducing bacteria are microorganisms that gain energy by transferring respiratory electrons to extracellular solid-phase electron acceptors. in addition to its importance for physiology and natural environmental processes, this form of metabolism is being investigated for energy conversion and fuel production in bioelectrochemical systems, where microbes are used as biocatalysts at electrodes. one proposed strategy to accomplish this extracellular charge transfer involves for ...201222797729
electromicrobiology.electromicrobiology deals with the interactions between microorganisms and electronic devices and with the novel electrical properties of microorganisms. a diversity of microorganisms can donate electrons to, or accept electrons from, electrodes without the addition of artificial electron shuttles. however, the mechanisms for microbe-electrode electron exchange have been seriously studied in only a few microorganisms. shewanella oneidensis interacts with electrodes primarily via flavins that fun ...201222746334
exploring the biochemistry at the extracellular redox frontier of bacterial mineral fe(iii) respiration.many species of the bacterial shewanella genus are notable for their ability to respire in anoxic environments utilizing insoluble minerals of fe(iii) and mn(iv) as extracellular electron acceptors. in shewanella oneidensis, the process is dependent on the decahaem electron-transport proteins that lie at the extracellular face of the outer membrane where they can contact the insoluble mineral substrates. these extracellular proteins are charged with electrons provided by an inter-membrane electr ...201222616858
characterisation of the dissimilatory reduction of fe(iii)-oxyhydroxide at the microbe-mineral interface: the application of stxm-xmcd.a combination of scanning transmission x-ray microscopy and x-ray magnetic circular dichroism was used to spatially resolve the distribution of different carbon and iron species associated with shewanella oneidensis mr-1 cells. s. oneidensis mr-1 couples the reduction of fe(iii)-oxyhydroxides to the oxidation of organic matter in order to conserve energy for growth. several potential mechanisms may be used by s. oneidensis mr-1 to facilitate fe(iii)-reduction. these include direct contact betwee ...201222515480
outer-membrane cytochrome-independent reduction of extracellular electron acceptors in shewanella oneidensis.dissimilatory metal reduction under ph-neutral conditions is dependent on an extended respiratory chain to the cell surface. the final reduction is catalysed by outer-membrane cytochromes that transfer respiratory electrons either directly to mineral surfaces and metal ions bound in larger organic complexes such as fe(iii) citrate, or indirectly using endogenous or exogenous electron shuttles such as humic acids and flavins. consequently, a shewanella oneidensis deletion mutant devoid of outer-m ...201222493303
physical constraints on charge transport through bacterial nanowires.extracellular appendages of the dissimilatory metal-reducing bacterium shewanella oneidensis mr-1 were recently shown to sustain currents of 10(10) electrons per second over distances of 0.5 microns [el-naggar et al., proc. natl. acad. sci. u. s. a., 2010, 107, 18127]. however, the identity of the charge localizing sites and their organization along the "nanowire" remain unknown. we use theory to predict redox cofactor separation distances that would permit charge flow at rates of 10(10) electro ...201222470966
a functional description of cyma, an electron-transfer hub supporting anaerobic respiratory flexibility in shewanella.cyma (tetrahaem cytochrome c) is a member of the napc/nirt family of quinol dehydrogenases. essential for the anaerobic respiratory flexibility of shewanellae, cyma transfers electrons from menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of fe(iii). spectroscopic characterization of cyma from shewanella oneidensis strain mr-1 identifies three low-spin his/his co-ordinated c-haems and a single high-spin c-haem with ...201222458729
removal of water-insoluble sudan dyes by shewanella oneidensis mr-1.decolorization of water-insoluble sudan dyes was studied with shewanella oneidensis mr-1, which removed 66.8%, 43.4%, 56.0% and 33.7% sudan i-iv in 104 h, respectively and reduced sudan i to aniline and 1-amino-2-naphthol. lactate was identified as the most efficient electron donor for sudan i reduction. improved reduction performance was obtained in the presence of higher lactate or biomass concentration. the correlation between specific reduction rate and initial sudan i concentration could be ...201222456237
growth inhibition and stimulation of shewanella oneidensis mr-1 by surfactants and calcium polysulfide.foam delivery technology (fdt) uses surfactant based foam to immobilize subsurface contaminants in situ. where traditional approaches are impractical, fdt has the potential to overcome many of the technical challenges facing the remediation of contaminated deep vadose zone environments. however, little is known about the effects these reactive chemicals may have on microorganisms inhabiting the contaminated subsurface. in addition, there are currently no standard assays to assess microbial respo ...201222444725
facile fabrication of scalable, hierarchically structured polymer/carbon architectures for bioelectrodes.this research introduces a method for fabrication of conductive electrode materials with hierarchical structure from porous polymer/carbon composite materials. we describe the fabrication of (3-hydroxybutyrate-co-3-hydroxyvalerate) (phbv) scaffolds doped with carbon materials that provide a conductive three-dimensional architecture that was demonstrated for application in microbial fuel cell (mfc) anodes. composite electrodes from phbv were fabricated to defined dimensions by solvent casting and ...201222394146
a voltammetric flavin microelectrode for use in biofilms.biofilms used in bioelectrochemical systems are expected to transfer electrons using electron transfer mediators. one mediator type, flavins, which includes flavin mononucleotide, riboflavin, and flavin adenine dinucleotide, has been found to be endogenously produced by shewanella oneidensis mr-1. however, the presence and concentration of flavins inside a s. oneidensis mr-1 biofilm have never been reported. the goal of this study was to develop a flavin microelectrode capable of measuring flavi ...201222368323
reconstruction of extracellular respiratory pathways for iron(iii) reduction in shewanella oneidensis strain mr-1.shewanella oneidensis strain mr-1 is a facultative anaerobic bacterium capable of respiring a multitude of electron acceptors, many of which require the mtr respiratory pathway. the core mtr respiratory pathway includes a periplasmic c-type cytochrome (mtra), an integral outer-membrane β-barrel protein (mtrb), and an outer-membrane-anchored c-type cytochrome (mtrc). together, these components facilitate transfer of electrons from the c-type cytochrome cyma in the cytoplasmic membrane to electron ...201222363330
role of outer membrane c-type cytochromes mtrc and omca in shewanella oneidensis mr-1 cell production, accumulation, and detachment during respiration on hematite.the iron-reducing bacterium shewanella oneidensis mr-1 has the capacity to contribute to iron cycling over the long term by respiring on crystalline iron oxides such as hematite when poorly crystalline phases are depleted. the ability of outer membrane cytochromes omca and mtrc of mr-1 to bind to and transfer electrons to hematite has led to the suggestion that they function as terminal reductases when this mineral is used as a respiratory substrate. differences in their redox behavior and hemat ...201222360295
high-pressure-induced water penetration into 3-isopropylmalate dehydrogenase.hydrostatic pressure induces structural changes in proteins, including denaturation, the mechanism of which has been attributed to water penetration into the protein interior. in this study, structures of 3-isopropylmalate dehydrogenase (ipmdh) from shewanella oneidensis mr-1 were determined at about 2 å resolution under pressures ranging from 0.1 to 650 mpa using a diamond anvil cell (dac). although most of the protein cavities are monotonically compressed as the pressure increases, the volume ...201222349232
biodecolorization of naphthol green b dye by shewanella oneidensis mr-1 under anaerobic conditions.the anaerobic decolorization of metal-complex dye naphthol green b (ngb) by a metal-reducing bacterium, shewanella oneidensis mr-1, was investigated. s. oneidensis mr-1 showed a high capacity for decolorizing ngb even at a concentration of up to 1000mg/l under anaerobic conditions. maximum decolorization efficiency was appeared at ph 8.0 and 40°c. addition of iron oxide caused no inhibition to the ngb decolorization, while the presence of ferric citrate, nitrite, or nitrate almost completely ter ...201222349191
identification and characterization of mtoa: a decaheme c-type cytochrome of the neutrophilic fe(ii)-oxidizing bacterium sideroxydans lithotrophicus es-1.the gram-negative bacterium sideroxydans lithotrophicus es-1 (es-1) grows on feco(3) or fes at oxic-anoxic interfaces at circumneutral ph, and the es-1-mediated fe(ii) oxidation occurs extracellularly. however, the molecular mechanisms underlying es-1's ability to oxidize fe(ii) remain unknown. survey of the es-1 genome for candidate genes for microbial extracellular fe(ii) oxidation revealed that it contained a three-gene cluster encoding homologs of shewanella oneidensis mr-1 (mr-1) mtra, mtrb ...201222347878
soluble electron shuttles can mediate energy taxis toward insoluble electron acceptors.shewanella species grow in widely disparate environments and play key roles in elemental cycling, especially in environments with varied redox conditions. to obtain a system-level understanding of shewanella's robustness and versatility, the complex interplay of cellular growth, metabolism, and transport under conditions of limiting carbon sources, energy sources, and electron acceptors must be elucidated. in this paper, population-level taxis of shewanella oneidensis mr-1 cells in the presence ...201222324484
transcriptional analysis of shewanella oneidensis mr-1 with an electrode compared to fe(iii)citrate or oxygen as terminal electron acceptor.shewanella oneidensis is a target of extensive research in the fields of bioelectrochemical systems and bioremediation because of its versatile metabolic capabilities, especially with regard to respiration with extracellular electron acceptors. the physiological activity of s. oneidensis to respire at electrodes is of great interest, but the growth conditions in thin-layer biofilms make physiological analyses experimentally challenging. here, we took a global approach to evaluate physiological a ...201222319591
integrating flux balance analysis into kinetic models to decipher the dynamic metabolism of shewanella oneidensis mr-1.shewanella oneidensis mr-1 sequentially utilizes lactate and its waste products (pyruvate and acetate) during batch culture. to decipher mr-1 metabolism, we integrated genome-scale flux balance analysis (fba) into a multiple-substrate monod model to perform the dynamic flux balance analysis (dfba). the dfba employed a static optimization approach (soa) by dividing the batch time into small intervals (i.e., ∼400 mini-fbas), then the monod model provided time-dependent inflow/outflow fluxes to con ...201222319437
influences of aerobic respiration on current generation by shewanella oneidensis mr-1 in single-chamber microbial fuel cells.in single-chamber microbial fuel cells (sc-mfcs), oxygen molecules diffuse through air cathodes into electrolytes and compete against anodes in accepting electrons. in this study, we constructed multiple gene-knockout mutants for terminal oxidases (so4607, so2364, and so3286) in shewanella oneidensis mr-1 and examined their abilities to generate electric currents in sc-mfcs. although single-knockout mutants generated levels of current similar to that of the wild type (wt), an so4607/so2364 doubl ...201222313754
polyethyleneimine-mediated flocculation of shewanella oneidensis mr-1: impacts of cell surface appendage and polymer concentration.in wastewater treatment plants, optimizing bacterial flocculation and bacterial sludge dewatering requires a detailed understanding of the concomitant biological and physico-chemical processes governing the action of flocculating agent on living cells. here we investigate the interactions between polyethyleneimine (pei, 60,000g/mol) and shewanella oneidensis mr-1 lacking or not the lipopolysaccharide (lps) o-antigen surface structure. flocculation tests were performed on bacteria with/without lp ...201222285041
biotic and abiotic reduction and solubilization of pu(iv)o₂•xh₂o(am) as affected by anthraquinone-2,6-disulfonate (aqds) and ethylenediaminetetraacetate (edta).this study measured reductive solubilization of plutonium(iv) hydrous oxide (pu(iv)o(2)·xh(2)o((am))) with hydrogen (h(2)) as electron donor, in the presence or absence of dissimilatory metal-reducing bacteria (dmrb), anthraquinone-2,6-disulfonate (aqds), and ethylenediaminetetraacetate (edta). in pipes buffer at ph 7 with excess h(2), shewanella oneidensis and geobacter sulfurreducens both solubilized <0.001% of 0.5 mm pu(iv)o(2)·xh(2)o((am)) over 8 days, with or without aqds. however, pu((aq)) ...201222276620
crystallization and preliminary x-ray crystallographic studies of the outer membrane cytochrome omca from shewanella oneidensis mr-1.the outer membrane cytochrome omca functions as a terminal metal reductase in the dissimilatory metal-reducing bacterium shewanella oneidensis mr-1. the ten-heme centers shuttle electrons from the transmembrane donor complex to extracellular electron acceptors. here, the crystallization and preliminary crystallographic analysis of omca are reported. crystals of omca were grown by the sitting-drop vapor-diffusion method using peg 20,000 as a precipitant. the omca crystals belonged to space group ...201222232171
long-range electron conduction of shewanella biofilms mediated by outer membrane c-type cytochromes.we investigated the role of c-type cytochromes (c-cyts) in electron conduction across biofilms of shewanella oneidensis mr-1 and the relevance of the electron conductivity for biological current generation. following the formation of monolayer and multilayer biofilms on indium-tin oxide electrodes, we quantified the c-cyts that were electrically wired with the electrode surface using whole-cell voltammetry. a multilayer biofilm with a thickness of 16μm exhibited a redox peak with an 8-fold large ...201222222436
the roles of outer membrane cytochromes of shewanella and geobacter in extracellular electron transfer.as key components of the electron transfer (et) pathways used for dissimilatory reduction of solid iron [fe(iii)] (hydr)oxides, outer membrane multihaem c-type cytochromes mtrc and omca of shewanella oneidensis mr-1 and omce and omcs of geobacter sulfurreducens mediate et reactions extracellularly. both mtrc and omca are at least partially exposed to the extracellular side of the outer membrane and their translocation across the outer membrane is mediated by bacterial type ii secretion system. p ...200923765850
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