scholarly journals Tuning Redox Potential of Anthraquinone-2-Sulfonate (AQS) by Chemical Modification to Facilitate Electron Transfer From Electrodes in Shewanella oneidensis

2021 ◽  
Vol 9 ◽  
Author(s):  
Ning Xu ◽  
Tai-Lin Wang ◽  
Wen-Jie Li ◽  
Yan Wang ◽  
Jie-Jie Chen ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Redox Potential ◽  
Environmental Remediation ◽  
Rational Design ◽  
Coulombic Efficiency ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Total Charge ◽  
Redox Potentials ◽  
Chemical Production

Bioelectrochemical systems (BESs) are emerging as attractive routes for sustainable energy generation, environmental remediation, bio-based chemical production and beyond. Electron shuttles (ESs) can be reversibly oxidized and reduced among multiple redox reactions, thereby assisting extracellular electron transfer (EET) process in BESs. Here, we explored the effects of 14 ESs on EET in Shewanella oneidensis MR-1, and found that anthraquinone-2-sulfonate (AQS) led to the highest cathodic current density, total charge production and reduction product formation. Subsequently, we showed that the introduction of -OH or -NH2 group into AQS at position one obviously affected redox potentials. The AQS-1-NH2 exhibited a lower redox potential and a higher Coulombic efficiency compared to AQS, revealing that the ESs with a more negative potential are conducive to minimize energy losses and improve the reduction of electron acceptor. Additionally, the cytochromes MtrA and MtrB were required for optimal AQS-mediated EET of S. oneidensis MR-1. This study will provide new clues for rational design of efficient ESs in microbial electrosynthesis.

scholarly journals Geothrix fermentans Secretes Two Different Redox-Active Compounds To Utilize Electron Acceptors across a Wide Range of Redox Potentials

2012 ◽  
Vol 78 (19) ◽  
pp. 6987-6995 ◽  
Author(s):  
Misha G. Mehta-Kolte ◽  
Daniel R. Bond
Keyword(s):  
Electron Transfer ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Extracellular Electron Transfer ◽  
Redox Potentials ◽  
Active Compounds ◽  
Content Type ◽  
Electron Shuttles ◽  
Redox Active ◽  
Geothrix Fermentans

ABSTRACTThe current understanding of dissimilatory metal reduction is based primarily on isolates from the proteobacterial generaGeobacterandShewanella. However, environments undergoing active Fe(III) reduction often harbor less-well-studied phyla that are equally abundant. In this work, electrochemical techniques were used to analyze respiratory electron transfer by the only known Fe(III)-reducing representative of theAcidobacteria,Geothrix fermentans. In contrast to previously characterized metal-reducing bacteria, which typically reach maximal rates of respiration at electron acceptor potentials of 0 V versus standard hydrogen electrode (SHE),G. fermentansrequired potentials as high as 0.55 V to respire at its maximum rate. In addition,G. fermentanssecreted two different soluble redox-active electron shuttles with separate redox potentials (−0.2 V and 0.3 V). The compound with the lower midpoint potential, responsible for 20 to 30% of electron transfer activity, was riboflavin. The behavior of the higher-potential compound was consistent with hydrophilic UV-fluorescent molecules previously found inG. fermentanssupernatants. Both electron shuttles were also produced when cultures were grown with Fe(III), but not when fumarate was the electron acceptor. This study reveals thatGeothrixis able to take advantage of higher-redox-potential environments, demonstrates that secretion of flavin-based shuttles is not confined toShewanella, and points to the existence of high-potential-redox-active compounds involved in extracellular electron transfer. Based on differences between the respiratory strategies ofGeothrixandGeobacter, these two groups of bacteria could exist in distinctive environmental niches defined by redox potential.

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>

Identifying the potential extracellular electron transfer pathways from a c-type cytochrome network

2014 ◽  
Vol 10 (12) ◽  
pp. 3138-3146 ◽  
Author(s):  
De-Wu Ding ◽  
Jun Xu ◽  
Ling Li ◽  
Jian-Ming Xie ◽  
Xiao Sun
Keyword(s):  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Genome Wide ◽  
A Genome ◽  
Electron Transfer Pathways

A genome-wide c-type cytochrome network was constructed to explore the extracellular electron transfer pathways in Shewanella 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.

scholarly journals Developing a population-state decision system for intelligently reprogramming extracellular electron transfer in Shewanella oneidensis

2020 ◽  
Vol 117 (37) ◽  
pp. 23001-23010 ◽  
Author(s):  
Feng-He Li ◽  
Qiang Tang ◽  
Yang-Yang Fan ◽  
Yang Li ◽  
Jie Li ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Bacterial Growth ◽  
Metabolic Flux ◽  
Expression System ◽  
Shewanella Oneidensis ◽  
Cellular Growth ◽  
Extracellular Electron Transfer ◽  
Regulation System ◽  
Growth State ◽  
Pollutant Reduction

The unique extracellular electron transfer (EET) ability has positioned electroactive bacteria (EAB) as a major class of cellular chassis for genetic engineering aimed at favorable environmental, energy, and geoscience applications. However, previous efforts to genetically enhance EET ability have often impaired the basal metabolism and cellular growth due to the competition for the limited cellular resource. Here, we design a quorum sensing-based population-state decision (PSD) system for intelligently reprogramming the EET regulation system, which allows the rebalanced allocation of the cellular resource upon the bacterial growth state. We demonstrate that the electron output from Shewanella oneidensis MR-1 could be greatly enhanced by the PSD system via shifting the dominant metabolic flux from initial bacterial growth to subsequent EET enhancement (i.e., after reaching a certain population-state threshold). The strain engineered with this system achieved up to 4.8-fold EET enhancement and exhibited a substantially improved pollutant reduction ability, increasing the reduction efficiencies of methyl orange and hexavalent chromium by 18.8- and 5.5-fold, respectively. Moreover, the PSD system outcompeted the constant expression system in managing EET enhancement, resulting in considerably enhanced electron output and pollutant bioreduction capability. The PSD system provides a powerful tool for intelligently managing extracellular electron transfer and may inspire the development of new-generation smart bioelectrical devices for various applications.

Sign in / Sign up

Export Citation Format

Share Document