scholarly journals A novel growth and isolation medium for exoelectrogenic bacteria

2021 ◽  
Author(s):  
Zumaira Nazeer ◽  
Eustace Fernando
Keyword(s):  
Growth Medium ◽  
Solid Medium ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
The Novel ◽  
Isolation Medium ◽  
Biochemical Characterisation ◽  
Electrochemically Active ◽  
Colour Changes ◽  
Exoelectrogenic Bacteria

A microbiological isolation and growth medium that can effectively discriminate electrochemically active exoelectrogenic bacteria from other non-exoelectrogenic bacteria, is currently unavailable. In this study, we developed a novel chromogenic growth and isolation solid medium based on MnO2 that can selectively allow the growth of exoelectrogenic bacteria and change the medium colour in the process. Known exoelectrogenic bacteria such as Shewanella oneidensis MR1 and other such bacteria from functional microbial fuel cell (MFC) anodes were capable of growing and changing colour in the novel growth medium. On the contrary, non-exoelectrogenic bacteria such as Escherichia coli ATCC 25922 were incapable of growing and inducing a colour changes in the novel medium. Further biochemical characterisation of these isolated exoelectrogenic bacteria by Raman micro-spectroscopy demonstrated that these bacteria over express cytochrome proteins that are vital in extracellular electron transfer events. This medium is a convenient method to isolate exoelectrogenic bacteria from complex environmental samples.

scholarly journals Cultivation of Exoelectrogenic Bacteria in Conductive DNA Nanocomposite Hydrogels Yields a Programmable Biohybrid Materials System

2019 ◽  
Author(s):  
Yong Hu ◽  
David Rehnlund ◽  
Edina Klein ◽  
Johannes Gescher ◽  
Christof M. Niemeyer
Keyword(s):  
Microbial Fuel Cells ◽  
Electrochemical Impedance ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Material System ◽  
Nanocomposite Hydrogels ◽  
The Matrix ◽  
Electrochemical Devices ◽  
Electron Transfer Pathways ◽  
Exoelectrogenic Bacteria

AbstractThe use of living microorganisms integrated within electrochemical devices is an expanding field of research, with applications in microbial fuel cells, microbial biosensors or bioreactors. We describe the use of porous nanocomposite materials prepared by DNA polymerization of carbon nanotubes (CNT) and silica nanoparticles (SiNP) for the construction of a programmable biohybrid system containing the exoelectrogenic bacterium Shewanella oneidensis. We initially demonstrate the electrical conductivity of the CNT-containing DNA composite by employment of chronopotentiometry, electrochemical impedance spectroscopy, and cyclic voltammetry. Cultivation of Shewanella oneidensis in these materials shows that the exoelectrogenic bacteria populate the matrix of the composite, while non-exoelectrogenic Escherichia coli remain on its surface. Moreover, the ability to use extracellular electron transfer pathways is positively correlated with number of cells within the conductive synthetic biofilm matrix. The Shewanella containing composite remains stable for several days. Programmability of this biohybrid material system is demonstrated by on-demand release and degradation induced by a short-term enzymatic stimulus. The perspectives of this approach for technical applications are being discussed.

Molecular mechanisms regulating the catabolic and electrochemical activities of Shewanella oneidensis MR-1

2021 ◽  
Author(s):  
Atsushi Kouzuma
Keyword(s):  
Microbial Fuel Cells ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Cellular Functions ◽  
Regulatory Systems ◽  
Electrochemically Active ◽  
Recent Developments

Abstract Electrochemically active bacteria (EAB) interact electrochemically with electrodes via extracellular electron transfer (EET) pathways. These bacteria have attracted significant attention due to their utility in environment-friendly bioelectrochemical systems (BESs), e.g. microbial fuel cells and electrofermentation systems. The electrochemical activity of EAB is dependent on their carbon catabolism and respiration; thus, understanding how these processes are regulated will provide insights into the development of a more efficient BES. The process of biofilm formation by EAB on BES electrodes is also important for electric current generation, because it facilitates physical and electrochemical interactions between EAB cells and electrodes. This article summarizes the current knowledge on EET-related metabolic and cellular functions of a model EAB, Shewanella oneidensis MR-1, focusing specifically on regulatory systems for carbon catabolism, EET pathways, and biofilm formation. Based on recent developments, the author also discusses potential uses of engineered S. oneidensis strains for various biotechnological applications.

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.

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.

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