scholarly journals Surface-induced formation and redox-dependent staining of outer membrane extensions inShewanella oneidensisMR-1

2019 ◽  
Author(s):  
Grace W. Chong ◽  
Sahand Pirbadian ◽  
Mohamed Y. El-Naggar
Keyword(s):  
Outer Membrane ◽  
Shewanella Oneidensis ◽  
Medium Composition ◽  
Extracellular Electron Transfer ◽  
Active Components ◽  
Transmission Electron ◽  
Redox Active ◽  
Redox Centers

AbstractThe metal-reducing bacteriumShewanella oneidensisMR-1 produces extensions of its outer membrane (OM) and periplasm that contain cytochromes responsible for extracellular electron transfer (EET) to external redox-active surfaces, including minerals and electrodes. While the role of multi-heme cytochromes in transporting electrons across the cell wall is well established, their distribution alongS. oneidensisOM extensions is also thought to allow lateral electron transport along these filaments. These proposed bacterial nanowires, which can be several times the cell length, would thereby extend EET to more distant electron acceptors. However, it is still unclear why these extensions form, and to what extent they contribute to respiration in living cells. Here, we investigate physical contributors to their formation usingin vivofluorescence microscopy. While previous studies focused on the display ofS. oneidensisouter membrane extensions (OMEs) as a response to oxygen limitation, we find that cell-to-surface contact is sufficient to trigger the production of OMEs, including some that reach >100 µm in length, irrespective of medium composition, agitation, or aeration. To visualize the extent of heme redox centers along OMEs, and help distinguish these structures from other extracellular filaments, we also performed histochemical redox-dependent staining with transmission electron microscopy on wild type and cytochrome-deficient strains. We demonstrate that redox-active components are limited to OMEs and not present on other extracellular appendages, such as pili and flagella. We also observed that the loss of 8 functional periplasmic and outer membrane cytochromes significantly decreased both the frequency and intensity of redox-dependent staining found widespread on OMEs. These results will improve our understanding of the environmental conditions that influence the formation ofS. oneidensisOMEs, as well as the distribution and functionality of EET components along extracellular appendages.

A ROLE OF PROTEINS OF THE OUTER MEMBRANE OF Shewanella oneidensis MR-1 BACTERIA IN FORMATION AND STABILIZATION OF SILVER SULFIDE NANOPARTICLES

2015 ◽  
pp. 41-48 ◽  
Author(s):  
T. A. Voeikova ◽  
A. S. Shebanova ◽  
Yu. D. Ivanov ◽  
A. L. Kaysheva ◽  
L. M. Novikova ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Shewanella Oneidensis ◽  
Silver Sulfide ◽  
Silver Sulfide Nanoparticles

Impact of Graphitic Structures in Pyrogenic Carbon on Microbial Reduction of Ferrihydrite

2021 ◽  
Author(s):  
wentao yu ◽  
baoliang chen
Keyword(s):  
Electron Transfer ◽  
Pyrolysis Temperature ◽  
Shewanella Oneidensis ◽  
Exchange Capacity ◽  
Microbial Reduction ◽  
Systematic Evaluation ◽  
Extracellular Electron Transfer ◽  
Pyrogenic Carbon ◽  
The Impact

<p>Pyrogenic carbon plays important roles in microbial reduction of ferrihydrite by shuttling electrons in the extracellular electron transfer (EET) processes. Despite its importance, a full assessment on the impact of graphitic structures in pyrogenic carbon on microbial reduction of ferrihydrite has not been conducted. This study is a systematic evaluation of microbial ferrihydrite reduction by Shewanella oneidensis MR-1 in the presence of pyrogenic carbon with various graphitization extents. The results showed that the rates and extents of microbial ferrihydrite reduction were significantly enhanced in the presence of pyrogenic carbon, and increased with increasing pyrolysis temperature. Combined spectroscopic and electrochemical analyses suggested that the rate of microbial ferrihydrite reduction were dependent on the electrical conductivity of pyrogenic carbon (i.e., graphitization extent), rather than the electron exchange capacity. The key role of graphitic structures in pyrogenic carbon in mediating EET was further evidenced by larger microbial electrolysis current with pyrogenic carbon prepared at higher pyrolysis temperatures. This study provides new insights into the electron transfer in the pyrogenic carbon-mediated microbial reduction of ferrihydrite.</p>

scholarly journals Spin-Dependent Electron Transport through Bacterial Cell Surface Multiheme Electron Conduits

2019 ◽  
Author(s):  
Suryakant Mishra ◽  
Sahand Pirbadian ◽  
Amit Kumar Mondal ◽  
Moh El-Naggar ◽  
Ron Naaman
Keyword(s):  
Electron Transport ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Long Distance ◽  
Force Microscopy ◽  
Bacterial Cell Surface ◽  
Redox Active ◽  
Gain Energy

Multiheme cytochromes, located on the bacterial cell surface, function as long-distance (> 10 nm) electron conduits linking intracellular reactions to external surfaces. This extracellular electron transfer process, which allows microorganisms to gain energy by respiring solid redox-active minerals, also facilitates the wiring of cells to electrodes. While recent studies suggested that a chiral induced spin selectivity effect is linked to efficient electron transmission through biomolecules, this phenomenon has not been investigated in the extracellular electron conduits. Using magnetic conductive probe atomic force microscopy, Hall voltage measurements, and spin-dependent electrochemistry of the decaheme cytochromes MtrF and OmcA from the metal-reducing bacterium <i>Shewanella oneidensis</i> MR-1, we show that electron transport through these extracellular conduits is spin-selective. Our study has implications for understanding how spin-dependent interactions and magnetic fields may control electron transport across biotic-abiotic interfaces in both natural and biotechnological systems.

THE INTERACTION OF BLOOD ELEMENTS WITH ENDOCARDIAL ENDOTHELIUM DAMAGED BY LACTIC ACID

1987 ◽  
Author(s):  
G Carter ◽  
B J Gavin
Keyword(s):  
Lactic Acid ◽  
Basal Lamina ◽  
Myocardial Infarct ◽  
Transmission Electron ◽  
Rat Hearts ◽  
Cacodylate Buffer ◽  
Aortic Cannula ◽  
Endocardial Endothelium

It has already been demonstrated that ischaemic metabolites, which could diffuse frcm a myocardial infarct in vivo, can cause substantial damage to the endocardial endotheliun and this could predispose to mural thrombosis.To investigate the role of ischaemic metabolites in the pathogenesis of mural thrombosis, lactic acid (pH6.4) was passed through a two-way concentric catheter ligated into the left ventricle of isolated beating rat hearts that were perfused with oxygenated Krebs-Henseleit buffer (KHB) through an aortic cannula. After periods of 1, 2, and 4 hours, the lactic acid was followed for 10 minutes by 10 mis of whole blood from hepa-rinized donor rats. Ventricles were then flushed with KHB, fixed in 2.5% glutaraldehyde and post-fixed in 1% osmium tetrox-ide in cacodylate buffer.Scanning and transmission electron microscopy showed that platelets adhered to exposed basal lamina, microfibrils and collagen but not to intact or damaged endothelial cells. However densely aggregated thrombi only farmed on regions of exposed connective tissue and never on basal lamina. Fibrin, leukocytes and red blood cells were associated with these platelet thrombi. Thus lactic acid and other ischaemic metabolites which could possibly diffuse in vivo from an infarct can contribute to endocardial damage which predisposes to mural thrombosis.

The surface (S-) layer is a virulence factor of Bacteroides forsythus

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3617-3627 ◽  
Author(s):  
M. Sabet ◽  
S.-W. Lee ◽  
R. K. Nauman ◽  
T. Sims ◽  
H.-S. Um
Keyword(s):  
Virulence Factor ◽  
Systemic Disease ◽  
Periodontal Pathogen ◽  
Whole Cells ◽  
Virulence Potential ◽  
Transmission Electron ◽  
Immunization Study ◽  
Antibody Inhibition

Bacteroides forsythus has emerged as a crucial periodontal pathogen with possible implications for systemic disease. The aim of this study was to isolate the S-layer from B. forsythus and examine its virulence potential as a part of efforts to characterize virulence factors of B. forsythus. The role of the S-layer in the haemagglutinating and adherent/invasive activities was evaluated. It was observed that the S-layer alone was able to mediate haemagglutination. In adherent and invasive studies, transmission electron microscopy clearly revealed that B. forsythus cells were able to attach to and invade KB cells, showing the formation of a microvillus-like extension around adherent and intracellular bacteria. The quantitative analysis showed that five different B. forsythus strains exhibited attachment (1·9–2·3 %) and invasion (0·4–0·7 %) capabilities. It was also observed through antibody inhibition assays that adherent/invasive activities of B. forsythus are mediated by the S-layer. Furthermore, an in vivo immunization study adopting a murine abscess model was used to prove that the S-layer is involved in the infectious process of abscess formation. While mice immunized with purified S-layer and B. forsythus whole cells did not develop any abscesses when challenged with viable B. forsythus cells, unimmunized mice developed abscesses. Collectively, the data obtained from these studies indicate that the S-layer of B. forsythus is a virulence factor.

The role of proteins of the outer membrane of Shewanella oneidensis MR-1 in the formation and stabilization of silver sulfide nanoparticles

2016 ◽  
Vol 52 (8) ◽  
pp. 769-775 ◽  
Author(s):  
T. A. Voeikova ◽  
A. S. Shebanova ◽  
Yu. D. Ivanov ◽  
A. L. Kaysheva ◽  
L. M. Novikova ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Shewanella Oneidensis ◽  
Silver Sulfide ◽  
Silver Sulfide Nanoparticles

scholarly journals Role of Humic Acid Chemical Structure Derived from Different Biomass Feedstocks on Fe(III) Bioreduction Activity: Implication for Sustainable Use of Bioresources

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 450 ◽  
Author(s):  
Yuquan Wei ◽  
Zimin Wei ◽  
Fang Zhang ◽  
Xiang Li ◽  
Wenbing Tan ◽  
...  
Keyword(s):  
Sustainable Use ◽  
Shewanella Oneidensis ◽  
Active Components ◽  
Chemical Structures ◽  
Mature Phase ◽  
Redox Active ◽  
Composition And Structure ◽  
Vis Spectroscopy ◽  
Humification Degree ◽  
Fe Reduction

Humic acids (HAs) are redox-active components that play a crucial role in catalyzing relevant redox reactions in various ecosystems. However, it is unclear what role the different compost-derived Has play in the dissimilatory Fe(III) bioreduction and which chemical structures could accelerate Fe reduction. In this study, we compared the effect of eighteen HAs from the mesophilic phase, thermophilic phase and mature phase of protein-, lignocellulose- and lignin-rich composting on catalyzing the bioreduction of Fe(III)-citrate by Shewanella oneidensis MR-1 in temporarily anoxic laboratory systems. The chemical composition and structure of different compost-derived HAs were analyzed by UV–Vis spectroscopy, excitation-emission matrices of the fluorescence spectra, and 13C-NMR. The results showed that HAs from lignocellulose- and lignin-rich composting, especially in the thermophilic phase, promoted the bioreduction of Fe(III). They also showed that HA from protein-rich materials suppressed significantly the Fe(II) production, which was mainly affected by the amount and structures of functional groups (e.g., quinone groups) and humification degree of the HAs. This study can aid in searching sustainable HA-rich composts for wide-ranging applications to catalyze redox-mediated reactions of pollutants in soils.

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