The conjugated oligoelectrolyte DSSN+ enables exceptional coulombic efficiency via direct electron transfer for anode-respiring Shewanella oneidensis MR-1—a mechanistic study

2014 ◽  
Vol 16 (38) ◽  
pp. 20436-20443 ◽  
Author(s):  
Nathan D. Kirchhofer ◽  
Xiaofen Chen ◽  
Enrico Marsili ◽  
James J. Sumner ◽  
Frederick W. Dahlquist ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Coulombic Efficiency ◽  
Direct Electron Transfer ◽  
Shewanella Oneidensis ◽  
Mechanistic Study ◽  
Electron Transfer Pathway

Biofilm electrochemistry reveals that DSSN+ increases coulombic efficiency by enhancing the native direct electron transfer pathway of S. oneidensis MR-1.

scholarly journals A Hybrid Extracellular Electron Transfer Pathway Enhances the Survival of Vibrio natriegens

2020 ◽  
Vol 86 (19) ◽  
Author(s):  
Bridget E. Conley ◽  
Matthew T. Weinstock ◽  
Daniel R. Bond ◽  
Jeffrey A. Gralnick
Keyword(s):  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Basic Research ◽  
Extracellular Electron Transfer ◽  
Content Type ◽  
Electron Transfer Pathway ◽  
Sedimentary Environments ◽  
Genetic Potential ◽  
Iron And Manganese

ABSTRACT Vibrio natriegens is the fastest-growing microorganism discovered to date, making it a useful model for biotechnology and basic research. While it is recognized for its rapid aerobic metabolism, less is known about anaerobic adaptations in V. natriegens or how the organism survives when oxygen is limited. Here, we describe and characterize extracellular electron transfer (EET) in V. natriegens, a metabolism that requires movement of electrons across protective cellular barriers to reach the extracellular space. V. natriegens performs extracellular electron transfer under fermentative conditions with gluconate, glucosamine, and pyruvate. We characterized a pathway in V. natriegens that requires CymA, PdsA, and MtrCAB for Fe(III) citrate and Fe(III) oxide reduction, which represents a hybrid of strategies previously discovered in Shewanella and Aeromonas. Expression of these V. natriegens genes functionally complemented Shewanella oneidensis mutants. Phylogenetic analysis of the inner membrane quinol dehydrogenases CymA and NapC in gammaproteobacteria suggests that CymA from Shewanella diverged from Vibrionaceae CymA and NapC. Analysis of sequenced Vibrionaceae revealed that the genetic potential to perform EET is conserved in some members of the Harveyi and Vulnificus clades but is more variable in other clades. We provide evidence that EET enhances anaerobic survival of V. natriegens, which may be the primary physiological function for EET in Vibrionaceae. IMPORTANCE Bacteria from the genus Vibrio occupy a variety of marine and brackish niches with fluctuating nutrient and energy sources. When oxygen is limited, fermentation or alternative respiration pathways must be used to conserve energy. In sedimentary environments, insoluble oxide minerals (primarily iron and manganese) are able to serve as electron acceptors for anaerobic respiration by microorganisms capable of extracellular electron transfer, a metabolism that enables the use of these insoluble substrates. Here, we identify the mechanism for extracellular electron transfer in Vibrio natriegens, which uses a combination of strategies previously identified in Shewanella and Aeromonas. We show that extracellular electron transfer enhanced survival of V. natriegens under fermentative conditions, which may be a generalized strategy among Vibrio spp. predicted to have this metabolism.

Mechanistic Study of ROS-photogeneration by Pterin

Pteridines ◽  
2011 ◽  
Vol 22 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Hong-Fang Ji ◽  
Liang Shen
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Direct Electron Transfer ◽  
Density Functional Theory Calculations ◽  
Electron Transfer Reaction ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Direct Energy ◽  
Electronic Parameters

Abstract Pterins are widespread in biological systems and possess photosensitizing activities. In the present study, the photosensitization mechanism of acid form of pterin (PTA) and basic form of pterin (PTB) is investigated by means of density functional theory calculations. The reactive oxygen species-photogenerating pathways of the lowest triplet excited (T1) state PTA and PTB are proposed as follows. Through direct energy transfer, both T1 state PTA and PTB can photogenerate 1O2. Two possible O2 .−-generating pathways are proposed according to the electronic parameters of PTA and PTB: i) direct electron transfer from T1 state PTA and PTB to 3O2 and the electron transfer reaction is more favorable energetically for PTB in comparison with PTA; and ii) electron transfer from anion radical of PTA and PTB to 3O2.

scholarly journals Pyruvate accelerates palladium reduction by regulating catabolism and electron transfer pathway in Shewanella oneidensis

2021 ◽  
Author(s):  
Yuan-Yuan Cheng ◽  
Wen-Jing Wang ◽  
Shi-Ting Ding ◽  
Ming-Xing Zhang ◽  
Ai-Guo Tang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Carbon Source ◽  
Time Window ◽  
Carbon Sources ◽  
Shewanella Oneidensis ◽  
Underlying Mechanism ◽  
Extracellular Electron Transfer ◽  
Resting Cells ◽  
Electron Transfer Pathway ◽  
Specific Regulation

Shewanella oneidensis is a model strain of the electrochemical active bacteria (EAB) because of its strong capability of extracellular electron transfer (EET) and genetic tractability. In this study, we investigated the effect of carbon sources on EET in S. oneidensis by using reduction of palladium ions (Pd(II)) as a model and found that pyruvate greatly accelerated the Pd(II) reduction compared with lactate by resting cells. Both Mtr pathway and hydrogenases played a role in Pd(II) reduction when pyruvate was used as a carbon source. Furthermore, in comparison with lactate-feeding S. oneidensis, the transcriptional levels of formate dehydrogenases involving in pyruvate catabolism, Mtr pathway, and hydrogenases in pyruvate-feeding S. oneidensis were up-regulated. Mechanistically, the enhancement of electron generation from pyruvate catabolism and electron transfer to Pd(II) explains the pyruvate effect on Pd(II) reduction. Interestingly, a 2-h time window is required for pyruvate to regulate transcription of these genes and profoundly improve Pd(II) reduction capability, suggesting a hierarchical regulation for pyruvate sensing and response in S. oneidensis. IMPORTANCE The unique respiration of EET is crucial for the biogeochemical cycling of metal elements and diverse applications of EAB. Although a carbon source is a determinant factor of bacterial metabolism, the research into the regulation of carbon source on EET is rare. In this work, we reported the pyruvate-specific regulation and improvement of EET in S. oneidensis and revealed the underlying mechanism, which suggests potential targets to engineer and improve the EET efficiency of this bacterium. This study sheds light on the regulatory role of carbon sources in anaerobic respiration in EAB, providing a way to regulate EET for diverse applications from a novel perspective.

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.

scholarly journals Protamine Promotes Direct Electron Transfer Between Shewanella Oneidensis Cells and Carbon Nanomaterials in Bacterial Biocomposites

2019 ◽  
Vol 6 (9) ◽  
pp. 2349-2349
Author(s):  
Stéphane Pinck ◽  
Frédéric P. A. Jorand ◽  
Mengjie Xu ◽  
Mathieu Etienne
Keyword(s):  
Electron Transfer ◽  
Carbon Nanomaterials ◽  
Direct Electron Transfer ◽  
Shewanella Oneidensis
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