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physiological roles of arca, crp, and etra and their interactive control on aerobic and anaerobic respiration in shewanella oneidensis.in the genome of shewanella oneidensis, genes encoding the global regulators arca, crp, and etra have been identified. all these proteins deviate from their counterparts in e. coli significantly in terms of functionality and regulon. it is worth investigating the involvement and relationship of these global regulators in aerobic and anaerobic respiration in s. oneidensis. in this study, the impact of the transcriptional factors arca, crp, and etra on aerobic and anaerobic respiration in s. oneid ...201021203399
integrative analysis of transcriptomic and proteomic data of shewanella oneidensis: missing value imputation using temporal datasets.despite significant improvements in recent years, proteomic datasets currently available still suffer from large number of missing values. integrative analyses based upon incomplete proteomic and transcriptomic datasets could seriously bias the biological interpretation. in this study, we applied a non-linear data-driven stochastic gradient boosted trees (gbt) model to impute missing proteomic values using a temporal transcriptomic and proteomic dataset of shewanella oneidensis. in this dataset, ...201121212895
monitoring microbial redox transformations of metal and metalloid elements under high pressure using in situ x-ray absorption spectroscopy.x-ray absorption spectroscopy is a well-established method for probing local structural and electronic atomic environments in a variety of systems. we used x-ray absorption near-edge structure (xanes) spectroscopy for monitoring in real-time conditions selenium reduction in situ in live cultures of shewanella oneidensis mr-1 under high hydrostatic pressure. high-quality xanes data show that shewanella oneidensis mr-1 reduces selenite se(iv) to red elemental selenium se(0) up to 150 mpa without a ...201121231995
biofabrication of discrete spherical gold nanoparticles using the metal-reducing bacterium shewanella oneidensis.nanocrystallites have garnered substantial interest due to their various applications, including catalysis and medical research. consequently important aspects of synthesis related to control of shape and size through economical and non-hazardous means are desirable. highly efficient bioreduction-based fabrication approaches that utilize microbes and/or plant extracts are poised to meet these needs. here we show that the γ-proteobacterium shewanella oneidensis can reduce tetrachloroaurate (iii) ...201121241833
extracellular polymeric substances from shewanella sp. hrcr-1 biofilms: characterization by infrared spectroscopy and proteomics.the composition of extracellular polymeric substances (eps) from shewanella sp. hrcr-1 biofilms was investigated using infrared spectroscopy and proteomics to provide insight into potential ecophysiological functions and redox activity of the eps. both bound and loosely associated eps were extracted from shewanella sp. hrcr-1 biofilms prepared using a hollow-fibre membrane biofilm reactor. fourier transform infrared spectra revealed the presence of proteins, polysaccharides, nucleic acids, membr ...201121251176
impacts of shewanella oneidensis c-type cytochromes on aerobic and anaerobic respiration.shewanella are renowned for their ability to utilize a wide range of electron acceptors (ea) for respiration, which has been partially accredited to the presence of a large number of the c-type cytochromes. to investigate the involvement of c-type cytochrome proteins in aerobic and anaerobic respiration of shewanella oneidensis mr -1, 36 in-frame deletion mutants, among possible 41 predicted, c-type cytochrome genes were obtained. the potential involvement of each individual c-type cytochrome in ...201021255343
bacterial decolorization of textile dyes is an extracellular process requiring a multicomponent electron transfer pathway.many studies have reported microorganisms as efficient biocatalysts for colour removal of dye-containing industrial wastewaters. we present the first comprehensive study to identify all molecular components involved in decolorization by bacterial cells. mutants from the model organism shewanella oneidensis mr-1, generated by random transposon and targeted insertional mutagenesis, were screened for defects in decolorization of an oxazine and diazo dye. we demonstrate that decolorization is an ext ...200821261820
indirect modulation of the intracellular c-di-gmp level in shewanella oneidensis mr-1 by mxda.the ggdef domain protein mxda, which is important for biofilm formation in shewanella oneidensis mr-1, was hypothesized to possess diguanylate cyclase activity. here, we demonstrate that while mxda controls the cellular level of c-di-gmp in s. oneidensis, it modulates the c-di-gmp pool indirectly.201121278272
towards electrosynthesis in shewanella: energetics of reversing the mtr pathway for reductive metabolism.bioelectrochemical systems rely on microorganisms to link complex oxidation/reduction reactions to electrodes. for example, in shewanella oneidensis strain mr-1, an electron transfer conduit consisting of cytochromes and structural proteins, known as the mtr respiratory pathway, catalyzes electron flow from cytoplasmic oxidative reactions to electrodes. reversing this electron flow to drive microbial reductive metabolism offers a possible route for electrosynthesis of high value fuels and chemic ...201121311751
tools for resolving complexity in the electron transfer networks of multiheme cytochromes c.examining electron transfer between two proteins with identical spectroscopic signatures is a challenging task. it is supposed that several multiheme cytochromes in shewanella oneidensis form a molecular "wire" through which electrons are transported across the cellular space and a direct study of this transient protein-protein interaction has not yet been reported. in this study, we present variations on catalytic protein film voltammetry and an anaerobic affinity chromatography assay to demons ...201121327265
pulsed multiple reaction monitoring approach to enhancing sensitivity of a tandem quadrupole mass spectrometer.liquid chromatography (lc)-triple quadrupole mass spectrometers operating in a multiple reaction monitoring (mrm) mode are increasingly used for quantitative analysis of low-abundance analytes in highly complex biochemical matrixes. after development and selection of optimum mrm transitions, sensitivity and data quality limitations are largely related to mass spectral peak interferences from sample or matrix constituents and statistical limitations at low number of ions reaching the detector. he ...201121344863
reproducibility and quantitation of amplicon sequencing-based detection.to determine the reproducibility and quantitation of the amplicon sequencing-based detection approach for analyzing microbial community structure, a total of 24 microbial communities from a long-term global change experimental site were examined. genomic dna obtained from each community was used to amplify 16s rrna genes with two or three barcode tags as technical replicates in the presence of a small quantity (0.1% wt/wt) of genomic dna from shewanella oneidensis mr-1 as the control. the techni ...201121346791
surface-enhanced raman imaging of intracellular bioreduction of chromate in shewanella oneidensis.this proposed research aims to use novel nanoparticle sensors and spectroscopic tools constituting surface-enhanced raman spectroscopy (sers) and fluorescence lifetime imaging (flim) to study intracellular chemical activities within single bioremediating microorganism. the grand challenge is to develop a mechanistic understanding of chromate reduction and localization by the remediating bacterium shewanella oneidensis mr-1 by chemical and lifetime imaging. mr-1 has attracted wide interest from t ...201121364911
partial functional replacement of cyma by sircd in shewanella oneidensis mr-1.the gammaproteobacterium shewanella oneidensis mr-1 utilizes a complex electron transfer network composed primarily of c-type cytochromes to respire under anoxic conditions a variety of compounds, including fumarate, nitrate, and dimethyl sulfoxide (dmso), in addition to the minerals fe(iii) and mn(iv). central to several respiratory pathways is cyma, a cytoplasmic membrane-bound tetraheme c-type cytochrome that functions as the major hydroquinone dehydrogenase. to investigate functional redunda ...201121378180
sers spectroscopy and sers imaging of shewanella oneidensis using silver nanoparticles and nanowires.facile and reproducible sers signals from shewanella oneidensis were obtained utilizing silver nanoparticles (agnps) and silver nanowires (agnws). additionally, sers images identify the distribution of sers hot-spots. one important observation is the synergistically enhanced sers signal when agnps and agnws are used in conjunction, due to constructively enhanced electromagnetic field.201121380475
cyclic voltammetric analysis of the electron transfer of shewanella oneidensis mr-1 and nanofilament and cytochrome knock-out mutants.shewanella is frequently used as a model microorganism for microbial bioelectrochemical systems. in this study, we used cyclic voltammetry (cv) to investigate extracellular electron transfer mechanisms from s. oneidensis mr-1 (wt) and five deletion mutants: membrane bound cytochrome (?mtrc/?omca), transmembrane pili (?pilm-q, ?mshh-q, and ?pilm-q/?mshh-q) and flagella (?flg). we demonstrate that the formal potentials of mediated and direct electron transfer sites of the derived biofilms can be g ...201121402501
the decolorisation capacity and mechanism of shewanella oneidensis mr-1 for methyl orange and acid yellow 199 under microaerophilic conditions.shewanella oneidensis mr-1 was found to reach 99.36% and 78.25% decolorisation for methyl orange and acid yellow 199 in solutions, respectively. the suitable ph range for decolorisation of methyl orange and acid yellow 199 by s. oneidensis mr-1 was 4.0-7.0 and 6.0-8.0, respectively, the azo dyes' removal by s. oneidensis mr-1 was slightly enhanced by addition of mg(2+), but inhibited by pb(2+), cd(2+), cu(2+), fe(3+) and fe(2+). the enzyme activities of nadh-dcip reductase and azoreductase were ...201121411946
a microfluidic microbial fuel cell fabricated by soft lithography.here we report a new microfluidic microbial fuel cell (mfc) platform built by soft-lithography techniques. the mfc design includes a unique sub-5 µl polydimethylsiloxane soft chamber featuring carbon cloth electrodes and microfluidic delivery of electrolytes. bioelectricity was generated using shewanella oneidensis mr-1 cultivated on either complex organic substrates or lactate-based minimal medium. these micro-mfcs exhibited fast start-ups, reproducible current generation, and enhanced power de ...201121421307
fnr (etra) acts as a fine-tuning regulator of anaerobic metabolism in shewanella oneidensis mr-1.etra in shewanella oneidensis mr-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators fnr in e. coli and anr in pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in shewanella spp. is complex and not well understood.201121450087
microbial electricity generation via microfluidic flow control.next generation battery technology is rapidly evolving to meet the demand for higher power densities and smaller footprints through novel catalysts and battery architecture. we present a µ-scale, biological fuel cell which utilizes microbial electricity generation enabled by microfluidic flow control to produce power. the new fuel cell, the smallest of its kind, with a total volume of 0.3 µl, produces scalable and controllable electrical energy from organic matter which is sustained through micr ...201121495007
extracellular reduction of hexavalent chromium by cytochromes mtrc and omca of shewanella oneidensis mr-1.to characterize the roles of cytochromes mtrc and omca of shewanella oneidensis mr-1 in cr(vi) reduction, the impacts of deleting mtrc and/or omca genes on cr(vi) reduction and cellular locations of reduced cr(iii) precipitates were investigated. compared to wild type (wt), deletion of mtrc decreased initial rate of cr(vi) reduction by 43.5%, while deletion of omca or both mtrc and omca lowered the rates by 53.4% and 68.9%, respectively. in wt cells, cr(iii) precipitates were detected by transmi ...201121498755
decolorization of azo dyes by shewanella oneidensis mr-1 in the presence of humic acids.the effects of humic acid (ha) on azo dye decolorization by shewanella oneidensis mr-1 were studied. it was found that ha species isolated from different sources could all accelerate the decolorization of acid red 27 (ar27). anoxic and anaerobic conditions were required for the enhancement of azo dye decolorization by ha. in the presence of 50 mg doc l(-1) aldrich ha, 15-29% increases in decolorization efficiencies of azo dyes with different structures were achieved in 11 h. the enhancing effect ...201121509566
random mutagenesis of the prokaryotic peptide transporter ydgr identifies potential periplasmic gating residues.the peptide transporter (ptr) family represents a group of proton-coupled secondary transporters responsible for bulk uptake of amino acids in the form of di- and tri-peptides, an essential process employed across species ranging from bacteria to humans. in order to identify amino acids critical for peptide transport in a prokaryotic ptr member, we have screened a library of mutants of the e. coli peptide transporter ydgr using a high-throughput substrate uptake assay. we have identified 31 sing ...201121558271
energy-dependent stability of shewanella oneidensis mr-1 biofilms.stability and resistance to dissolution are key features of microbial biofilms. how these macroscopic properties are determined by the physiological state of individual biofilm cells in their local physical-chemical and cellular environment is largely unknown. in order to obtain molecular and energetic insight into biofilm stability, we investigated whether maintenance of biofilm stability is an energy-dependent process and whether transcription and/or translation are required for biofilm dissol ...201121572002
deciphering the electron transport pathway for graphene oxide reduction by shewanella oneidensis mr-1.we determined that graphene oxide reduction by shewanella oneidensis mr-1 requires the mtr respiratory pathway by analyzing a range of mutants lacking these proteins. electron-shuttling compounds accelerated graphene oxide reduction rate by 3 to 5 fold. these results may help facilitate the use of bacteria for large-scale graphene production.201121602337
a shewanella oneidensis mr-1 sensory box protein involved in aerobic and anoxic growth.although little is known of potential function for conserved signaling proteins, it is hypothesized that such proteins play important roles to coordinate cellular responses to environmental stimuli. in order to elucidate function for a putative sensory box protein (pas domains) in shewanella oneidensis mr-1, the physiological role of so3389 was characterized. the predicted orf encodes a putative sensory box protein that has pas, ggdef, and eal domains, and an in-frame, deletion mutant was constr ...201121602393
structure of a bacterial cell surface decaheme electron conduit.some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. in shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. the cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or pa ...201121606337
so2426 is a positive regulator of siderophore expression in shewanella oneidensis mr-1.abstract: background: the shewanella oneidensis mr-1 genome encodes a predicted orphan dna-binding response regulator, so2426. previous studies with a so2426-deficient mr-1 strain suggested a putative functional role for so2426 in the regulation of iron acquisition genes, in particular, the siderophore (hydroxamate) biosynthesis operon so3030-3031-3032. to further investigate the functional role of so2426 in iron homeostasis, we employed computational strategies to identify putative gene targets ...201121624143
raman chemical imaging of chromate reduction sites in a single bacterium using intracellularly grown gold nanoislands.imaging live molecular events within micro-organisms at single-cell resolution would deliver valuable mechanistic information much needed in understanding key biological processes. we present a surface-enhanced raman (sers) chemical imaging strategy as a first step toward exploring the intracellular bioreduction pockets of toxic chromate in shewanella. in order to achieve this, we take advantage of an innate reductive mechanism in bacteria of reducing gold ions into intracellular gold nanoisland ...201121634405
redox and ph microenvironments within shewanella oneidensis mr-1 biofilms reveal electron transfer mechanism.the goal of this research was to quantify the variations in redox potential and ph in shewanella oneidensis mr-1 biofilms respiring on electrodes. we grew s. oneidensis mr-1 on a graphite electrode, which was used to accept electrons for microbial respiration. we modified well-known redox and ph microelectrodes with a built-in reference electrode so that they could operate near polarized surfaces and quantified the redox potential and ph profiles in these biofilms. in addition, we used a ferri / ...201121648431
the luxs mutation causes loosely-bound biofilms in shewanella oneidensis.abstract:201121663678
bacterial formation of extracellular u(vi) nanowires.shewanella oneidensis mr-1 rapidly accumulates long, extracellular, u(vi) nanowires composed of polycrystalline chains of discrete meta-schoepite (uo(3)-à2h(2)o) nanocrystallites. the production of uranium(vi) nanowires could provide a novel strategy for remediation of uranium contamination in sediments and aquifers, as well as the recovery of uranium in manufacturing processes.201121681306
mapping the iron binding site(s) on the small tetraheme cytochrome of shewanella oneidensis mr-1.in the model microbe shewanella oneidensis, multi-heme proteins are utilized for respiratory metabolism where metals serve as the terminal electron acceptor. among those is the periplasm-localized small tetraheme cytochrome (stc). stc has been extensively characterized structurally and electrochemically to which electron flow in and out of the protein has been modeled. however, until the present work, no kinetic studies have been performed to probe the route of electron flow or to determine the ...201121682327
highly sensitive detection of proteins and bacteria in aqueous solution using surface-enhanced raman scattering and optical fibers.we report the detection of the proteins lysozyme and cytochrome c as well as the live bacterial cells of shewanella oneidensis mr-1 in aqueous solutions with sensitivities order(s) of magnitude higher than those previously reported. two highly sensitive surface-enhanced raman scattering (sers)-based biosensors using optical fibers have been employed for such label-free macromolecule detections. the first sensor is based on a tip-coated multimode fiber (tcmmf) with a double-substrate "sandwich" s ...201121692506
roles of two shewanella oneidensis mr-1 extracellular endonucleases.the dissimilatory iron-reducing bacterium shewanella oneidensis mr-1 is capable of using extracellular dna (edna) as the sole source of carbon, phosphorus, and nitrogen. in addition, we recently demonstrated that s. oneidensis mr-1 requires edna as a structural component during all stages of biofilm formation. in this study, we characterize the roles of two shewanella extracellular endonucleases, exes and exem. while exes is likely secreted into the medium, exem is predicted to remain associated ...201121705528
nile red detection of bacterial hydrocarbons and ketones in a high-throughput format.a method for use in high-throughput screening of bacteria for the production of long-chain hydrocarbons and ketones by monitoring fluorescent light emission in the presence of nile red is described. nile red has previously been used to screen for polyhydroxybutyrate (phb) and fatty acid esters, but this is the first report of screening for recombinant bacteria making hydrocarbons or ketones. the microtiter plate assay was evaluated using wild-type and recombinant strains of shewanella oneidensis ...201121712420
purification and characterization of the [nife]-hydrogenase of shewanella oneidensis mr-1.shewanella oneidensis mr-1 possesses a periplasmic [nife]-hydrogenase (mr-1 [nife]-h(2)ase) that has been implicated in h(2) production and oxidation as well as technetium [tc(vii)] reduction. to characterize the roles of mr-1 [nife]-h(2)ase in these proposed reactions, the genes encoding both subunits of mr-1 [nife]-h(2)ase were cloned and then expressed in an mr-1 mutant without hyab and hyda genes. expression of recombinant mr-1 [nife]-h(2)ase in trans restored the mutant's ability to produce ...201121724888
identification and analysis of the shewanella oneidensis major oxygen-independent coproporphyrinogen iii oxidase gene.shewanella oneidenesis mr-1 is a facultative anaerobe that can use a large number of electron acceptors including metal oxides. during anaerobic respiration, s. oneidensis mr-1 synthesizes a large number of c cytochromes that give the organism its characteristic orange color. using a modified mariner transposon, a number of s. oneidensis mutants deficient in anaerobic respiration were generated. one mutant, bg163, exhibited reduced pigmentation and was deficient in c cytochromes normally synthes ...201121726654
genetic and molecular characterization of flagellar assembly in shewanella oneidensis.shewanella oneidensis is a highly motile organism by virtue of a polar flagellum. unlike most flagellated bacteria, it contains only one major chromosome segment encoding the components of the flagellum with the exception of the motor proteins. in this region, three genes encode flagellinsaccording to the original genome annotation. however, we find that only flaa and flab encode functional filament subunits. although these two genesare under the control of different promoters, they are actively ...201121731763
identification of c-type heme-containing peptides using nonactivated immobilized metal affinity chromatography resin enrichment and higher-energy collisional dissociation.the c-type cytochromes play essential roles in many biological activities of both prokaryotic and eukaryotic cells, including electron transfer, enzyme catalysis, and induction of apoptosis. we report a novel enrichment strategy for identifying c-type heme-containing peptides that uses nonactivated imac resin. the strategy demonstrated at least 7-fold enrichment for heme-containing peptides digested from a cytochrome c protein standard, and quantitative linear performance was also assessed for h ...201121740036
investigation of the electron transport chain to and the catalytic activity of the diheme cytochrome c peroxidase ccpa of shewanella oneidensis.bacterial diheme c-type cytochrome peroxidases (bccps) catalyze the periplasmic reduction of hydrogen peroxide to water. the gammaproteobacterium shewanella oneidensis produces the peroxidase ccpa under a number of anaerobic conditions, including dissimilatory iron-reducing conditions. we wanted to understand the function of this protein in the organism and its putative connection to the electron transport chain to ferric iron. ccpa was isolated and tested for peroxidase activity, and its struct ...201121742904
monodispersed biocompatible silver sulfide nanoparticles: facile extracellular biosynthesis using the γ-proteobacterium, shewanella oneidensis.interest in engineered metal and semiconductor nanocrystallites continues to grow due to their unique size- and shape-dependent optoelectronic, physicochemical and biological properties. therefore identifying novel non-hazardous nanoparticle synthesis routes that address hydrophilicity, size and shape control and production costs has become a priority. in the present article we report for the first time on the efficient generation of extracellular silver sulfide (ag(2)s) nanoparticles by the met ...201121798382
anaerobic biodecolorization mechanism of methyl orange by shewanella oneidensis mr-1.in this work, we investigated the anaerobic decolorization of methyl orange (mo), a typical azo dye, by shewanella oneidensis mr-1, which can use various organic and inorganic substances as its electron acceptor in natural and engineered environments. s. oneidensis mr-1 was found to be able to obtain energy for growth through anaerobic respiration accompanied with dissimilatory azo-reduction of mo. chemical analysis shows that mo reduction occurred via the cleavage of azo bond. block of mtr resp ...201121808969
so2907, a putative tonb-dependent receptor, is involved in dissimilatory iron reduction by shewanella oneidensis mr-1.shewanella oneidensis strain mr-1 utilizes soluble and insoluble ferric ions as terminal electron acceptors during anaerobic respiration. the components of respiratory metabolism are localized in the membrane fractions which include the outer membrane and cytoplasmic membrane. many of the biological components that interact with the various iron forms are proposed to be localized in these membrane fractions. to identify the iron-binding proteins acting either as an iron transporter or as a termi ...201121813652
crystal structure of the complex between 4-hydroxybutyrate coa-transferase from clostridium aminobutyricum and coa.clostridium aminobutyricum ferments 4-aminobutyrate (+¦-aminobutyrate, gaba) to ammonia, acetate and butyrate via 4-hydroxybutyrate that is activated to the coa-thioester catalyzed by 4-hydroxybutyrate coa-transferase. then, 4-hydroxybutyryl-coa is dehydrated to crotonyl-coa, which disproportionates to butyryl-coa and acetyl-coa. cocrystallization of the coa-transferase with the alternate substrate butyryl-coa yielded crystals with non-covalently bound coa and two water molecules at the active s ...201121833509
solution-based structural analysis of the decaheme cytochrome, mtra, by small-angle x-ray scattering and analytical ultracentrifugation.the potential exploitation of metal-reducing bacteria as a means for environmental cleanup or alternative fuel is an exciting prospect; however, the cellular processes that would allow for these applications need to be better understood. mtra is a periplasmic decaheme c-type cytochrome from shewanella oneidensis involved in the reduction of extracellular iron oxides and therefore is a critical element in shewanella ability to engage in extracellular charge transfer. as a relatively small 333-res ...201121838277
control of proteobacterial central carbon metabolism by the hexr transcriptional regulator: a case study in shewanella oneidensis.bacteria exploit multiple mechanisms for controlling central carbon metabolism (ccm). thus, a bioinformatic analysis together with some experimental data implicated the hexr transcriptional factor as a global ccm regulator in some lineages of gammaproteobacteria operating as a functional replacement of the cra regulator characteristic of enterobacteriales. in this study, we combined a large scale comparative genomic reconstruction of hexr-controlled regulons in 87 species of proteobacteria with ...201121849503
cu-doped tio(2) nanoparticles enhance survival of shewanella oneidensis mr-1 under ultraviolet light (uv) exposure.it has been shown that photocatalytic tio(2) nanoparticles (nps) can be used as an efficient anti-microbial agent under uv light due to generation of reactive oxygen species (ros), while shewanella oneidensis mr-1 is a metal-reducing bacterium highly susceptible to uv radiation. interestingly, we found that the presence of cu-doped tio(2) nps in the cultural medium dramatically increased the survival rates (based on colony-forming unit) of strain mr-1 by over 10,000-fold (incubation without shak ...201121855961
biosupported bimetallic pd-au nanocatalysts for dechlorination of environmental contaminants.biologically produced monometallic palladium nanoparticles (bio-pd) have been shown to catalyze the dehalogenation of environmental contaminants, but fail to efficiently catalyze the degradation of other important recalcitrant halogenated compounds. this study represents the first report of biologically produced bimetallic pd/au nanoparticle catalysts. the obtained catalysts were tested for the dechlorination of diclofenac and trichlorethylene. when aqueous bivalent pd(ii) and trivalent au(iii) ...201121877727
Functional assessment of EnvZ/OmpR two-component system in Shewanella oneidensis.EnvZ and OmpR constitute the bacterial two-component signal transduction system known to mediate osmotic stress response in a number of gram-negative bacteria. In an effort to understand the mechanism through which Shewanella oneidensis senses and responds to environmental osmolarity changes, structure of the ompR-envZ operon was determined with Northern blotting assay and roles of the EnvZ/OmpR two-component system in response to various stresses were investigated with mutational analysis, quan ...201121886811
analysis of the bara/uvry two-component system in shewanella oneidensis mr-1.the bara/uvry two-component system is well conserved in species of the γ-proteobacteria and regulates numerous processes predominantly by controlling the expression of a subset of noncoding small rnas. in this study, we identified and characterized the bara/uvry two-component system in the gammaproteobacterium shewanella oneidensis mr-1. functional interaction of sensor kinase bara and the cognate response regulator uvry was indicated by in vitro phosphotransfer studies. the expression of two pr ...201121931597
towards a structural understanding of drug and peptide transport within the proton-dependent oligopeptide transporter (pot) family.one of the principal aims of modern drug design is the targeted delivery of drugs within the body, such as to the central nervous system, combined with their exclusion from the liver and kidneys, which break down foreign molecules and subsequently eliminate them. many of the commonly prescribed drugs are transported into cells and across the plasma membrane via endogenous membrane transporters, whose principal roles are the uptake of essential nutrients for metabolism. in many cases, such drug t ...201121936814
manganese sulfide formation via concomitant microbial manganese oxide and thiosulfate reduction.the dissimilatory metal-reducing bacterium, shewanella oneidensis mr-1 produced γ-mns (rambergite) nanoparticles during the concurrent reduction of mno₂ and thiosulfate coupled to h₂ oxidation. to investigate effect of direct microbial reduction of mno₂ on mns formation, two mr-1 mutants defective in outer membrane c-type cytochromes (δmtrc/δomca and δmtrc/δomca/δmtrf) were also used and it was determined that direct reduction of mno₂ was dominant relative to chemical reduction by biogenic sulfi ...201121951417
Identification of nicotinamide mononucleotide deamidase of the bacterial pyridine nucleotide cycle reveals a novel broadly conserved amidohydrolase family.The pyridine nucleotide cycle is a network of salvage and recycling routes maintaining homeostasis of NAD(P) cofactor pool in the cell. Nicotinamide mononucleotide (NMN) deamidase (EC 3.5.1.42), one of the key enzymes of the bacterial pyridine nucleotide cycle, was originally described in Enterobacteria, but the corresponding gene eluded identification for over 30 years. A genomics-based reconstruction of NAD metabolism across hundreds of bacterial species suggested that NMN deamidase reaction i ...201121953451
Optimal method for efficiently removing extracellular nanofilaments from Shewanella oneidensis MR-1.The identification, production, and potential electron conductivity of bacterial extracellular nanofilaments is an area of great study, specifically in Shewanella oneidensis MR-1. While some studies focus on nanofilaments attached to the cellular body, many studies require the removal of these nanofilaments for downstream applications. The removal of nanofilaments from S. oneidensis MR-1 for further study requires not only that the nanofilaments be detached, but also for the cell bodies to remai ...201121963962
pyruvate and lactate metabolism by shewanella oneidensis mr-1 under fermentation, oxygen limitation, and fumarate respiration conditions.shewanella oneidensis mr-1 is a facultative anaerobe that derives energy by coupling organic matter oxidation to the reduction of a wide range of electron acceptors. here, we quantitatively assessed the lactate and pyruvate metabolism of mr-1 under three distinct conditions: electron acceptor-limited growth on lactate with o(2), lactate with fumarate, and pyruvate fermentation. the latter does not support growth but provides energy for cell survival. using physiological and genetic approaches co ...201121965410
transient storage of electrical charge in biofilms of shewanella oneidensis mr-1 growing in a microbial fuel cell.current output of microbial fuel cells (mfcs) depends on a number of engineering variables mainly related to the design of the fuel cell reactor and the materials used. in most cases the engineering of mfcs relies on the premise that for a constant biomass, current output correlates well with the metabolic activity of the cells. in this study we analyze to what extent, mfc output is also affected by the mode of operation, emphasizing how discontinuous operation can affect temporal patterns of cu ...201121981730
targeted protein degradation of outer membrane decaheme cytochrome mtrc metal reductase in shewanella oneidensis mr-1 measured using biarsenical probe crash-edt(2).development of efficient microbial biofuel cells requires an ability to exploit interfacial electron transfer reactions to external electron acceptors, such as metal oxides; such reactions occur in the facultative anaerobic gram-negative bacterium shewanella oneidensis mr-1 through the catalytic activity of the outer membrane decaheme c-type cytochrome mtrc. central to the utility of this pathway to synthetic biology is an understanding of cellular mechanisms that maintain optimal mtrc function, ...201121999518
lactate oxidation coupled to iron or electrode reduction by geobacter sulfurreducens pca.geobacter sulfurreducens pca completely oxidized lactate and reduced iron or an electrode, producing pyruvate and acetate intermediates. compared to the current produced by shewanella oneidensis mr-1, g. sulfurreducens pca produced 10-times-higher current levels in lactate-fed microbial electrolysis cells. the kinetic and comparative analyses reported here suggest a prominent role of g. sulfurreducens strains in metal- and electrode-reducing communities supplied with lactate.201122003020
construction and elementary mode analysis of a metabolic model for shewanella oneidensis mr-1.a stoichiometric model describing the central metabolism of shewanella oneidensis mr-1 wild-type and derivative strains was developed and used in elementary mode analysis (ema). shewanella oneidensis mr-1 can anaerobically respire a diverse pool of electron acceptors, and may be applied in several biotechnology settings, including bioremediation of toxic metals, electricity generation in microbial fuel cells, and whole-cell biocatalysis. the metabolic model presented here was adapted and verifie ...201122024451
selection of shewanella oneidensis mr-1 gene-knockout mutants that adapt to an electrode-respiring condition.mutants of shewanella oneidensis mr-1 that adapted to an electrode-respiring condition were selected from a random transposon-insertion mutant library to obtain active current-generating mutants and identify relevant cellular components. the mutants were selected in the presence of an electrode (poised at +0.2 v vs. an ag/agcl reference electrode) as the sole electron acceptor, and they were isolated on agar plates. transposon-insertion sites in the isolated mutants were identified by inverse pc ...201122056453
enhanced performance and mechanism study of microbial electrolysis cells using fe nanoparticle-decorated anodes.anode properties are critical for the performance of microbial electrolysis cells (mecs). in the present study, fe nanoparticle-modified graphite disks were used as anodes to investigate the effects of nanoparticles on the performance of shewanella oneidensis mr-1 in mecs. results demonstrated that the average current densities produced with fe nanoparticle-decorated anodes up to 5.89-fold higher than plain graphite anodes. whole genome microarray analysis of the gene expression showed that gene ...201122080340
Roles of siderophore in manganese-oxide reduction by Shewanella oneidensis MR-1.Dissimilatory metal-reducing bacteria (DMRB), such as Shewanella oneidensis MR-1, are of great interest for their importance in the biogeochemical cycling of metals and utility in biotechnological processes, such as bioremediation and microbial fuel cells. To identify genes necessary for metal reduction, this study constructed a random transposon-insertion mutant library of MR-1 and screened it for isolating mutants that were deficient in metal reduction. Examination of approximately 5000 mutant ...201222092340
High frequency of glucose-utilizing mutants in Shewanella oneidensis MR-1.Shewanella oneidensis MR-1 has conventionally been considered unable to use glucose as a carbon substrate for growth. The genome sequence of S. oneidensis MR-1 however suggests the ability to use glucose. Here, we demonstrate that during initial glucose exposure, S. oneidensis MR-1 quickly and frequently gains the ability to utilize glucose as a sole carbon source, in contrast to wild-type S. oneidensis, which cannot immediately use glucose as a sole carbon substrate. High-performance liquid chr ...201122092702
resin-based investigation of acyl carrier protein interaction networks in escherichia coli.protein-protein interactions play an integral role in metabolic regulation. elucidation of these networks is complicated by the changing identity of the proteins themselves. here we demonstrate a resin-based technique that leverages the unique tools for acyl carrier protein (acp) modification with non-hydrolyzable linkages. acps from escherichia coli and shewanella oneidensis mr-1 are bound to affigel-15 with varying acyl groups attached and introduced to proteomic samples. isolation of these bi ...201122104437
Fabrication of macroporous chitosan scaffolds doped with carbon nanotubes and their characterization in microbial fuel cell operation.Chitosan (CHIT) scaffolds doped with multi-walled carbon nanotubes (CNT) were fabricated and evaluated for their utility as a microbial fuel cell (MFC) anodic material. High resolution microscopy verified the ability of Shewanella oneidensis MR-1 to directly colonize CHIT-CNT scaffolds. Cross-linking agents 1-ethyl-3-[3-dimethylaminopropyl] carbodimide hydrochloride (EDC), glutaraldehyde and glyoxal were independently studied for their ability to strengthen the CHIT-CNT matrix without disrupting ...201122113017
Comparative bioelectricity production from various wastewaters in microbial fuel cells using mixed cultures and a pure strain of Shewanella oneidensis.Current and power density from four wastewaters, agriculture (AWW), domestic (DWW), paper (PWW), and food/dairy (FDWW), were comparatively evaluated in combination with three inocula: wastewater endogenous microbes (MFC1), Shewanella oneidensis MR-1 (MFC2), and wastewater endogenous microbes with MR-1 (MFC3) in single chamber microbial fuel cells (MFC). Using AWW (0.011mA/cm(2); 0.0013mW/cm(2)) and DWW (0.017mA/cm(2); 0.0036mW/cm(2)), MFC2 was the best candidate providing the maximum current, wh ...201222123299
evidence-based annotation of gene function in shewanella oneidensis mr-1 using genome-wide fitness profiling across 121 conditions.most genes in bacteria are experimentally uncharacterized and cannot be annotated with a specific function. given the great diversity of bacteria and the ease of genome sequencing, high-throughput approaches to identify gene function experimentally are needed. here, we use pools of tagged transposon mutants in the metal-reducing bacterium shewanella oneidensis mr-1 to probe the mutant fitness of 3,355 genes in 121 diverse conditions including different growth substrates, alternative electron acc ...201122125499
The Response of Shewanella oneidensis MR-1 to Cr(III) Toxicity Differs from that to Cr(VI).Chromium is a contaminant of concern that is found in drinking water in its soluble, hexavalent form [Cr(VI)] and that is known to be toxic to eukaryotes and prokaryotes. Trivalent chromium [Cr(III)] is thought to be largely harmless due to its low solubility and inability to enter cells. Previous work has suggested that Cr(III) may also be toxic to microorganisms but the mechanism remained elusive. In this work, we probe the toxicity of Cr(III) to Shewanella oneidensis MR-1, a bacterium able to ...201122125549
Aggrandizing power output from Shewanella oneidensis MR-1 microbial fuel cells using calcium chloride.There are several interconnected metabolic pathways in bacteria essential for the conversion of carbon electron sources directly into electrical currents using microbial fuel cells (MFCs). This study establishes a direct exogenous method to increase power output from a Shewanella oneidensis MR-1 containing MFC by adding calcium chloride to the culture medium. The current output from each CaCl(2) concentration tested revealed that the addition of CaCl(2) to 1400µM increased the current density by ...201222154401
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
transcriptome analysis of pellicle formation of shewanella oneidensis.although the pellicle is one of the major growth modes of microorganisms, the metabolic features of pellicle cells and the determinative factors for pellicle formation are largely unknown. in recent years, biofilm development of shewanella oneidensis, an important model organism for bioremediation studies, has been extensively studied. in this paper, a transcriptional profiling of pellicle cells relative to planktonic cells indicated that cells in pellicles were more metabolically active than th ...201222228442
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
the diheme cytochrome c peroxidase from shewanella oneidensis requires reductive activation.we report the characterization of the diheme cytochrome c peroxidase (ccp) from shewanella oneidensis (so) using uv-visible absorbance, electron paramagnetic resonance spectroscopy, and michaelis-menten kinetics. while sequence alignment with other bacterial diheme cytochrome c peroxidases suggests that so ccp may be active in the as-isolated state, we find that so ccp requires reductive activation for full activity, similar to the case for the canonical pseudomonas type of bacterial ccp enzyme. ...201222239664
involvement of cytochrome c cyma in the anaerobic metabolism of rdx by shewanella oneidensis mr-1.hexahydro-1,3,5-trinitro-1,3,5-triazine (rdx) is a cyclic nitramine explosive commonly used for military applications that is responsible for severe soil and groundwater contamination. in this study, shewanella oneidensis mr-1 was shown to efficiently degrade rdx anaerobically (3.5 µmol·h(-1)·(g protein)(-1)) via two initial routes: (1) sequential n-no(2) reductions to the corresponding nitroso (n-no) derivatives (94% of initial rdx degradation) and (2) denitration followed by ring cleavage. t ...201222260206
adenylylation control by intra- or intermolecular active-site obstruction in fic proteins.fic proteins that are defined by the ubiquitous fic (filamentation induced by cyclic amp) domain are known to catalyse adenylylation (also called ampylation); that is, the transfer of amp onto a target protein. in mammalian cells, adenylylation of small gtpases through fic proteins injected by pathogenic bacteria can cause collapse of the actin cytoskeleton and cell death. it is unknown how this potentially deleterious adenylylation activity is regulated in the widespread fic proteins that are f ...201222266942
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
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
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
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
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
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
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
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
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
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
molecular underpinnings of fe(iii) oxide reduction by shewanella oneidensis mr-1.in the absence of o(2) and other electron acceptors, the gram-negative bacterium shewanella oneidensis mr-1 can use ferric [fe(iii)] (oxy)(hydr)oxide minerals as the terminal electron acceptors for anaerobic respiration. at circumneutral ph and in the absence of strong complexing ligands, fe(iii) oxides are relatively insoluble and thus are external to the bacterial cells. s. oneidensis mr-1 and related strains of metal-reducing shewanella have evolved machinery (i.e., metal-reducing or mtr path ...201222363328
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
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
laue crystal structure of shewanella oneidensis cytochrome c nitrite reductase from a high-yield expression system.the high-yield expression and purification of shewanella oneidensis cytochrome c nitrite reductase (ccnir) and its characterization by a variety of methods, notably laue crystallography, are reported. a key component of the expression system is an artificial ccnir gene in which the n-terminal signal peptide from the highly expressed s. oneidensis protein "small tetraheme c" replaces the wild-type signal peptide. this gene, inserted into the plasmid phsg298 and expressed in s. oneidensis tsp-1 st ...201222382353
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
non-enzymatic palladium recovery on microbial and synthetic surfaces.the use of microorganisms as support for reduction of dissolved pd(ii) to immobilized pd(0) nanoparticles is an environmentally friendly approach for pd recovery from waste. to better understand and engineer pd(0) nanoparticle synthesis, one has to consider the mechanisms by which pd(ii) is reduced on microbial surfaces. escherichia coli, shewanella oneidensis, and pseudomonas putida were used as model organisms in order to elucidate the role of microbial cells in pd(ii) reduction under acidic c ...201222422611
structural analysis of 3-isopropylmalate dehydrogenase from the obligate piezophile shewanella benthica db21mt-2 and the nonpiezophile shewanella oneidensis mr-1.organisms living in deep seas such as the mariana trench must be adapted to the extremely high pressure environment. for example, the 3-isopropylmalate dehydrogenase from the obligate piezophile shewanella benthica db21mt-2 (sbipmdh) remains active in extreme conditions under which that from the land bacterium s. oneidensis mr-1 (soipmdh) becomes inactivated. in order to unravel the differences between these two ipmdhs, their structures were determined at ~1.5 å resolution. comparison of the str ...201222442218
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
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
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
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
functional specificity of extracellular nucleases of shewanella oneidensis mr-1.bacterial species such as shewanella oneidensis mr-1 require extracellular nucleolytic activity for the utilization of extracellular dna (edna) as a source of nutrients and for the turnover of edna as a structural matrix component during biofilm formation. we have previously characterized two extracellular nucleases of s. oneidensis mr-1, exem and exes. although both are involved in biofilm formation, they are not specifically required for the utilization of edna as a nutrient. here we identifie ...201222492434
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
characterization of member of duf1888 protein family, self-cleaving and self-assembling endopeptidase.the crystal structure of so1698 protein from shewanella oneidensis was determined by a sad method and refined to 1.57 å. the structure is a β sandwich that unexpectedly consists of two polypeptides; the n-terminal fragment includes residues 1-116, and the c-terminal one includes residues 117-125. electron density also displayed the lys-98 side chain covalently linked to asp-116. the putative active site residues involved in self-cleavage were identified; point mutants were produced and character ...201222493430
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