scholarly journals Evidence for Direct Electron Transfer by a Gram-Positive Bacterium Isolated from a Microbial Fuel Cell

2011 ◽  
Vol 77 (21) ◽  
pp. 7633-7639 ◽  
Author(s):  
K. C. Wrighton ◽  
J. C. Thrash ◽  
R. A. Melnyk ◽  
J. P. Bigi ◽  
K. G. Byrne-Bailey ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Cell Envelope ◽  
Direct Electron Transfer ◽  
Surrounding Medium ◽  
Anode Surface ◽  
Extracellular Electron Transfer ◽  
Gram Positive ◽  
Content Type

ABSTRACTDespite their importance in iron redox cycles and bioenergy production, the underlying physiological, genetic, and biochemical mechanisms of extracellular electron transfer by Gram-positive bacteria remain insufficiently understood. In this work, we investigated respiration byThermincola potensstrain JR, a Gram-positive isolate obtained from the anode surface of a microbial fuel cell, using insoluble electron acceptors. We found no evidence that soluble redox-active components were secreted into the surrounding medium on the basis of physiological experiments and cyclic voltammetry measurements. Confocal microscopy revealed highly stratified biofilms in which cells contacting the electrode surface were disproportionately viable relative to the rest of the biofilm. Furthermore, there was no correlation between biofilm thickness and power production, suggesting that cells in contact with the electrode were primarily responsible for current generation. These data, along with cryo-electron microscopy experiments, support contact-dependent electron transfer byT. potensstrain JR from the cell membrane across the 37-nm cell envelope to the cell surface. Furthermore, we present physiological and genomic evidence thatc-type cytochromes play a role in charge transfer across the Gram-positive bacterial cell envelope during metal reduction.

scholarly journals Lack of Electricity Production by Pelobacter carbinolicus Indicates that the Capacity for Fe(III) Oxide Reduction Does Not Necessarily Confer Electron Transfer Ability to Fuel Cell Anodes

2007 ◽  
Vol 73 (16) ◽  
pp. 5347-5353 ◽  
Author(s):  
Hanno Richter ◽  
Martin Lanthier ◽  
Kelly P. Nevin ◽  
Derek R. Lovley
Keyword(s):  
Electron Transfer ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Microbial Fuel Cells ◽  
Electron Donors ◽  
Rrna Genes ◽  
Anode Surface ◽  
Oxide Reduction ◽  
Fuel Cell Anodes

ABSTRACT The ability of Pelobacter carbinolicus to oxidize electron donors with electron transfer to the anodes of microbial fuel cells was evaluated because microorganisms closely related to Pelobacter species are generally abundant on the anodes of microbial fuel cells harvesting electricity from aquatic sediments. P. carbinolicus could not produce current in a microbial fuel cell with electron donors which support Fe(III) oxide reduction by this organism. Current was produced using a coculture of P. carbinolicus and Geobacter sulfurreducens with ethanol as the fuel. Ethanol consumption was associated with the transitory accumulation of acetate and hydrogen. G. sulfurreducens alone could not metabolize ethanol, suggesting that P. carbinolicus grew in the fuel cell by converting ethanol to hydrogen and acetate, which G. sulfurreducens oxidized with electron transfer to the anode. Up to 83% of the electrons available in ethanol were recovered as electricity and in the metabolic intermediate acetate. Hydrogen consumption by G. sulfurreducens was important for ethanol metabolism by P. carbinolicus. Confocal microscopy and analysis of 16S rRNA genes revealed that half of the cells growing on the anode surface were P. carbinolicus, but there was a nearly equal number of planktonic cells of P. carbinolicus. In contrast, G. sulfurreducens was primarily attached to the anode. P. carbinolicus represents the first Fe(III) oxide-reducing microorganism found to be unable to produce current in a microbial fuel cell, providing the first suggestion that the mechanisms for extracellular electron transfer to Fe(III) oxides and fuel cell anodes may be different.

Heterocyclic aminopyrazine–reduced graphene oxide coated carbon cloth electrode as an active bio-electrocatalyst for extracellular electron transfer in microbial fuel cells

RSC Advances ◽  
2016 ◽  
Vol 6 (73) ◽  
pp. 68827-68834 ◽  
Author(s):  
Praveena Gangadharan ◽  
Indumathi M. Nambi ◽  
Jaganathan Senthilnathan ◽  
Pavithra V. M.
Keyword(s):  
Electron Transfer ◽  
Graphene Oxide ◽  
Fuel Cell ◽  
Reduced Graphene Oxide ◽  
Microbial Fuel Cell ◽  
Microbial Fuel Cells ◽  
Extracellular Electron Transfer ◽  
Carbon Cloth ◽  
Reduced Graphene ◽  
Coated Carbon

In the present study, a low molecular heterocyclic aminopyrazine (Apy)–reduced graphene oxide (r-GO) hybrid coated carbon cloth (r-GO–Apy–CC) was employed as an active and stable bio-electro catalyst in a microbial fuel cell (MFC).

scholarly journals A Carbon-Cloth Anode Electroplated with Iron Nanostructure for Microbial Fuel Cell Operated with Real Wastewater

2020 ◽  
Vol 12 (16) ◽  
pp. 6538 ◽  
Author(s):  
Enas Taha Sayed ◽  
Hussain Alawadhi ◽  
Khaled Elsaid ◽  
A. G. Olabi ◽  
Maryam Adel Almakrani ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Anode Surface ◽  
Carbon Cloth ◽  
Steady State Current ◽  
Real Wastewater ◽  
Improved Performance

Microbial fuel cell (MFC) is an emerging method for extracting energy from wastewater. The power generated from such systems is low due to the sluggish electron transfer from the inside of the biocatalyst to the anode surface. One strategy for enhancing the electron transfer rate is anode modification. In this study, iron nanostructure was synthesized on a carbon cloth (CC) via a simple electroplating technique, and later investigated as a bio-anode in an MFC operated with real wastewater. The performance of an MFC with a nano-layer of iron was compared to that using bare CC. The results demonstrated that the open-circuit voltage increased from 600 mV in the case of bare CC to 800 mV in the case of the iron modified CC, showing a 33% increase in OCV. This increase in OCV can be credited to the decrease in the anode potential from 0.16 V vs. Ag/AgCl in the case of bare CC, to −0.01 V vs. Ag/AgCl in the case of the modified CC. The power output in the case of the modified electrode was 80 mW/m2—two times that of the MFC using the bare CC. Furthermore, the steady-state current in the case of the iron modified carbon cloth was two times that of the bare CC electrode. The improved performance was correlated to the enhanced electron transfer between the microorganisms and the iron-plated surface, along with the increase of the anode surface- as confirmed from the electrochemical impedance spectroscopy and the surface morphology, respectively.

scholarly journals Flavin Electron Shuttles Dominate Extracellular Electron Transfer by Shewanella oneidensis

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicholas J. Kotloski ◽  
Jeffrey A. Gralnick
Keyword(s):  
Electron Transfer ◽  
Direct Electron Transfer ◽  
Shewanella Oneidensis ◽  
Phenotypic Characterization ◽  
Extracellular Electron Transfer ◽  
Wild Type ◽  
Content Type ◽  
Electron Shuttling ◽  
Electron Shuttles ◽  
Set Up

ABSTRACT 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 secrete flavins. A multidrug and toxin efflux transporter encoded by SO_0702 was identified and renamed bfe (bacterial flavin adenine dinucleotide [FAD] exporter) based on phenotypic characterization. Deletion of bfe resulted in a severe decrease in extracellular flavins, while overexpression of bfe increased the concentration of extracellular flavins. Strains lacking bfe had no defect in reduction of soluble Fe(III), but these strains were deficient in the rate of insoluble Fe(III) oxide reduction, which was alleviated by the addition of exogenous flavins. To test a different insoluble electron acceptor, graphite electrode bioreactors were set up to measure current produced by wild-type S. oneidensis and the Δbfe mutant. With the same concentration of supplemented flavins, the two strains produced similar amounts of current. However, when exogenous flavins were not supplemented to bioreactors, bfe mutant strains produced significantly less current than the wild type. We have demonstrated that flavin electron shuttling accounts for ~75% of extracellular electron transfer to insoluble substrates by S. oneidensis and have identified the first FAD transporter in bacteria. IMPORTANCE Extracellular electron transfer by microbes is critical for the geochemical cycling of metals, bioremediation, and biocatalysis using electrodes. A controversy in the field was addressed by demonstrating that flavin electron shuttling, not direct electron transfer or nanowires, is the primary mechanism of extracellular electron transfer employed by the bacterium Shewanella oneidensis. We have identified a flavin adenine dinucleotide transporter conserved in all sequenced Shewanella species that facilitates export of flavin electron shuttles in S. oneidensis. Analysis of a strain that is unable to secrete flavins demonstrated that electron shuttling accounts for ~75% of the insoluble extracellular electron transfer capacity in S. oneidensis.

Rechargeable microbial fuel cell based on bidirectional extracellular electron transfer

2021 ◽  
Vol 329 ◽  
pp. 124887
Author(s):  
Na Chu ◽  
Lixia Zhang ◽  
Wen Hao ◽  
Qinjun Liang ◽  
Yong Jiang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Extracellular Electron Transfer

scholarly journals Complete Genome Sequence of Raoultella electrica 1GB (DSM 102253T), Isolated from Anodic Biofilms of a Glucose-Fed Microbial Fuel Cell

2019 ◽  
Vol 8 (43) ◽  
Author(s):  
Simone Thiel ◽  
Boyke Bunk ◽  
Cathrin Spröer ◽  
Jörg Overmann ◽  
Dieter Jahn ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Dna Sequences ◽  
Plasmid Dna ◽  
Complete Genome Sequence ◽  
Microbial Fuel Cells ◽  
Complete Genome ◽  
Type Strain ◽  
Content Type

The type strain Raoultella electrica 1GB (DSM 102253T) was isolated from anodic biofilms of glucose-fed microbial fuel cells. The fully assembled, closed, circular 5.27-Mb genome and corresponding 0.52-Mb plasmid DNA sequences were elucidated. Potential electron transfer and pathogenicity mechanisms were deduced.

scholarly journals Two Routes for Extracellular Electron Transfer in Enterococcus faecalis

2020 ◽  
Vol 202 (7) ◽  
Author(s):  
Lars Hederstedt ◽  
Lo Gorton ◽  
Galina Pankratova
Keyword(s):  
Electron Transfer ◽  
Enterococcus Faecalis ◽  
Microbial Fuel Cells ◽  
Cell Envelope ◽  
Reductase Activity ◽  
Reducing Power ◽  
Extracellular Electron Transfer ◽  
Ferric Reductase ◽  
Ferric Ions ◽  
Content Type

ABSTRACT Enterococcus faecalis cells are known to have ferric reductase activity and the ability to transfer electrons generated in metabolism to the external environment. We have isolated mutants defective in ferric reductase activity and studied their electron transfer properties to electrodes mediated by ferric ions and an osmium complex-modified redox polymer (OsRP). Electron transfer mediated with ferric ions and ferric reductase activity were both found to be dependent on the membrane-associated Ndh3 and EetA proteins, consistent with findings in Listeria monocytogenes. In contrast, electron transfer mediated with OsRP was independent of these two proteins. Quinone in the cell membrane was required for the electron transfer with both mediators. The combined results demonstrate that extracellular electron transfer from reduced quinone to ferric ions and to OsRP occurs via different routes in the cell envelope of E. faecalis. IMPORTANCE The transfer of reducing power in the form of electrons, generated in the catabolism of nutrients, from a bacterium to an extracellular acceptor appears to be common in nature. The electron acceptor can be another cell or abiotic material. Such extracellular electron transfer contributes to syntrophic metabolism and is of wide environmental, industrial, and medical importance. Electron transfer between microorganisms and electrodes is fundamental in microbial fuel cells for energy production and for electricity-driven synthesis of chemical compounds in cells. In contrast to the much-studied extracellular electron transfer mediated by cell surface exposed cytochromes, little is known about components and mechanisms for such electron transfer in organisms without these cytochromes and in Gram-positive bacteria such as E. faecalis, which is a commensal gut lactic acid bacterium and opportunistic pathogen.

scholarly journals Extracellular Electron Transfer: Respiratory or Nutrient Homeostasis?

2020 ◽  
Vol 202 (7) ◽  
Author(s):  
Lars J. C. Jeuken ◽  
Kiel Hards ◽  
Yoshio Nakatani
Keyword(s):  
Electron Transfer ◽  
Iron Reduction ◽  
Ferric Iron ◽  
Shewanella Oneidensis ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Nutrient Homeostasis

ABSTRACT Exoelectrogens are able to transfer electrons extracellularly, enabling them to respire on insoluble terminal electron acceptors. Extensively studied exoelectrogens, such as Geobacter sulfurreducens and Shewanella oneidensis, are Gram negative. More recently, it has been reported that Gram-positive bacteria, such as Listeria monocytogenes and Enterococcus faecalis, also exhibit the ability to transfer electrons extracellularly, although it is still unclear whether this has a function in respiration or in redox control of the environment, for instance, by reducing ferric iron for iron uptake. In this issue of Journal of Bacteriology, Hederstedt and colleagues report on experiments that directly compare extracellular electron transfer (EET) pathways for ferric iron reduction and respiration and find a clear difference (L. Hederstedt, L. Gorton, and G. Pankratova, J Bacteriol 202:e00725-19, 2020, https://doi.org/10.1128/JB.00725-19), providing further insights and new questions into the function and metabolic pathways of EET in Gram-positive bacteria.

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