scholarly journals Microfluidic Microbial Bioelectrochemical Systems: An Integrated Investigation Platform for a More Fundamental Understanding of Electroactive Bacterial Biofilms

2020 ◽  
Vol 8 (11) ◽  
pp. 1841
Author(s):  
Stéphane Pinck ◽  
Lucila Martínez Ostormujof ◽  
Sébastien Teychené ◽  
Benjamin Erable
Keyword(s):  
Analytical Techniques ◽  
Extracellular Electron Transfer ◽  
Bioelectrochemical Systems ◽  
Material Transport ◽  
Biological Investigation ◽  
Interfacial Conditions ◽  
Experimental Systems ◽  
Fundamental Understanding ◽  
Catalytic Mechanisms ◽  
Microfabrication Techniques

It is the ambition of many researchers to finally be able to close in on the fundamental, coupled phenomena that occur during the formation and expression of electrocatalytic activity in electroactive biofilms. It is because of this desire to understand that bioelectrochemical systems (BESs) have been miniaturized into microBES by taking advantage of the worldwide development of microfluidics. Microfluidics tools applied to bioelectrochemistry permit even more fundamental studies of interactions and coupled phenomena occurring at the microscale, thanks, in particular, to the concomitant combination of electroanalysis, spectroscopic analytical techniques and real-time microscopy that is now possible. The analytical microsystem is therefore much better suited to the monitoring, not only of electroactive biofilm formation but also of the expression and disentangling of extracellular electron transfer (EET) catalytic mechanisms. This article reviews the details of the configurations of microfluidic BESs designed for selected objectives and their microfabrication techniques. Because the aim is to manipulate microvolumes and due to the high modularity of the experimental systems, the interfacial conditions between electrodes and electrolytes are perfectly controlled in terms of physicochemistry (pH, nutrients, chemical effectors, etc.) and hydrodynamics (shear, material transport, etc.). Most of the theoretical advances have been obtained thanks to work carried out using models of electroactive bacteria monocultures, mainly to simplify biological investigation systems. However, a huge virgin field of investigation still remains to be explored by taking advantage of the capacities of microfluidic BESs regarding the complexity and interactions of mixed electroactive biofilms.

scholarly journals Microfluidics-based Bioassays and Imaging of Plant Cells

2021 ◽  
Author(s):  
Naoki Yanagisawa ◽  
Elena Kozgunova ◽  
Guido Grossmann ◽  
Anja Geitmann ◽  
Tetsuya Higashiyama
Keyword(s):  
High Resolution ◽  
Agar Plate ◽  
Root Hairs ◽  
Plant Cells ◽  
Individual Plant ◽  
Experimental Systems ◽  
Surrounding Matrix ◽  
Sense And Respond ◽  
Physical And Chemical ◽  
Microfabrication Techniques

Abstract Many plant processes occur in the context of and in interaction with a surrounding matrix such as soil (e.g. root growth and root–microbe interactions) or surrounding tissues (e.g. pollen tube growth through the pistil), making it difficult to study them with high-resolution optical microscopy. Over the past decade, microfabrication techniques have been developed to produce experimental systems that allow researchers to examine cell behavior in microstructured environments that mimic geometrical, physical and/or chemical aspects of the natural growth matrices and that cannot be generated using traditional agar plate assays. These microfabricated environments offer considerable design flexibility as well as the transparency required for high-resolution, light-based microscopy. In addition, microfluidic platforms have been used for various types of bioassays, including cellular force assays, chemoattraction assays, and electrotropism assays. Here, we review the recent use of microfluidic devices to study plant cells and organs, including plant roots, root hairs, moss protonemata, and pollen tubes. The increasing adoption of microfabrication techniques by the plant science community may transform our approaches to investigating how individual plant cells sense and respond to changes in the physical and chemical environment.

Microbial iron-redox cycling in subsurface environments

2012 ◽  
Vol 40 (6) ◽  
pp. 1249-1256 ◽  
Author(s):  
Eric E. Roden
Keyword(s):  
Electron Transfer ◽  
Iron Oxidation ◽  
Anaerobic Respiration ◽  
Redox Cycling ◽  
Rapid Expansion ◽  
Extracellular Electron Transfer ◽  
Experimental Systems ◽  
Subsurface Environments ◽  
Micro Organisms ◽  
Iron Redox

In addition to its central role in mediating electron-transfer reactions within all living cells, iron undergoes extracellular redox transformations linked to microbial energy generation through utilization of Fe(II) as a source of chemical energy or Fe(III) as an electron acceptor for anaerobic respiration. These processes permit microbial populations and communities to engage in cyclic coupled iron oxidation and reduction within redox transition zones in subsurface environments. In the present paper, I review and synthesize a few case studies of iron-redox cycling in subsurface environments, highlighting key biochemical aspects of the extracellular iron-redox metabolisms involved. Of specific interest are the coupling of iron oxidation and reduction in field and experimental systems that model redox gradients and fluctuations in the subsurface, and novel pathways and organisms involved in the redox cycling of insoluble iron-bearing minerals. These findings set the stage for rapid expansion in our knowledge of the range of extracellular electron-transfer mechanisms utilized by subsurface micro-organisms. The observation that closely coupled oxidation and reduction of iron can take place under conditions common to the subsurface motivates this expansion in pursuit of molecular tools for studying iron-redox cycling communities in situ.

Bacterial extracellular electron transfer in bioelectrochemical systems

2012 ◽  
Vol 47 (12) ◽  
pp. 1707-1714 ◽  
Author(s):  
Yonggang Yang ◽  
Meiying Xu ◽  
Jun Guo ◽  
Guoping Sun
Keyword(s):  
Electron Transfer ◽  
Extracellular Electron Transfer ◽  
Bioelectrochemical Systems

scholarly journals How thermophilic Gram-positive organisms perform extracellular electron transfer: characterization of the cell surface terminal reductase OcwA

2019 ◽  
Author(s):  
N.L. Costa ◽  
B. Hermann ◽  
V. Fourmond ◽  
M. Faustino ◽  
M. Teixeira ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cell Surface ◽  
Electron Acceptors ◽  
Added Value ◽  
Extracellular Electron Transfer ◽  
Bioelectrochemical Systems ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Evolutionary Pathway ◽  
Structural And Functional Properties

AbstractExtracellular electron transfer is the key process underpinning the development of bioelectrochemical systems for the production of energy or added-value compounds. Thermincola potens JR is a promising Gram-positive bacterium to be used in these systems because it is thermophilic. In this paper we describe the structural and functional properties of the nonaheme cytochrome OcwA, which is the terminal reductase of this organism. The structure of OcwA, determined at 2.2Å resolution shows that the overall-fold and organization of the hemes are not related to other metal reductases and instead are similar to that of multiheme cytochromes involved in the biogeochemical cycles of nitrogen and sulfur. We show that, in addition to solid electron acceptors, OcwA can also reduce soluble electron shuttles and oxyanions. These data reveal that OcwA can take the role of a respiratory ‘swiss-army knife’ allowing this organism to grow in environments with rapidly changing availability of terminal electron acceptors without the need for transcriptional regulation and protein synthesis.ImportanceThermophilic Gram-positive organisms were recently shown to be a promising class of organisms to be used in bioelectrochemical systems for the production of electrical energy. These organisms present a thick peptidoglycan layer that was thought to preclude them to perform extracellular electron transfer (i.e. exchange catabolic electrons with solid electron acceptors outside of the cell). In this manuscript we describe the structure and functional mechanisms of the multiheme cytochrome OcwA, the terminal reductase of the Gram-positive bacterium Thermincola potens JR found at the cell surface of this organism. The results presented here show that this protein is unrelated with terminal reductases found at the cell surface of other electroactive organisms. Instead, OcwA is similar to terminal reductases of soluble electron acceptors. Our data reveals that terminal oxidoreductases of soluble and insoluble substrates are evolutionarily related, providing novel insights into the evolutionary pathway of multiheme cytochromes.

scholarly journals Nanotechnology to rescue bacterial bidirectional extracellular electron transfer in bioelectrochemical systems

RSC Advances ◽  
2016 ◽  
Vol 6 (36) ◽  
pp. 30582-30597 ◽  
Author(s):  
Shafeer Kalathil ◽  
Deepak Pant
Keyword(s):  
Electron Transfer ◽  
Electrode Materials ◽  
Extracellular Electron Transfer ◽  
Bioelectrochemical Systems ◽  
Nanostructured Electrode

Advanced nanostructured electrode materials largely improve the bacterial bidirectional extracellular electron transfer in bioelectrochemical systems.

scholarly journals Structure and Functions of Hydrocarbon-Degrading Microbial Communities in Bioelectrochemical Systems

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 343 ◽  
Author(s):  
Anna Espinoza-Tofalos ◽  
Matteo Daghio ◽  
Enza Palma ◽  
Federico Aulenta ◽  
Andrea Franzetti
Keyword(s):  
Microbial Community ◽  
Bacterial Communities ◽  
Anaerobic Degradation ◽  
Extracellular Electron Transfer ◽  
Bioelectrochemical Systems ◽  
Genetic Potential ◽  
Complex Functions ◽  
Metagenome Sequencing ◽  
Metagenomic Approach ◽  
Structure And Functions

Bioelectrochemical systems (BESs) exploit the interaction between microbes and electrodes. A field of application thereof is bioelectrochemical remediation, an effective strategy in environments where the absence of suitable electron acceptors limits classic bioremediation approaches. Understanding the microbial community structure and genetic potential of anode biofilms is of great interest to interpret the mechanisms occurring in BESs. In this study, by using a whole metagenome sequencing approach, taxonomic and functional diversity patterns in the inoculum and on the anodes of three continuous-flow BES for the removal of phenol, toluene, and BTEX were obtained. The genus Geobacter was highly enriched on the anodes and two reconstructed genomes were taxonomically related to the Geobacteraceae family. To functionally characterize the microbial community, the genes coding for the anaerobic degradation of toluene, ethylbenzene, and phenol were selected as genetic markers for the anaerobic degradation of the pollutants. The genes related with direct extracellular electron transfer (EET) were also analyzed. The inoculum carried the genetic baggage for the degradation of aromatics but lacked the capacity of EET while anodic bacterial communities were able to pursue both processes. The metagenomic approach provided useful insights into the ecology and complex functions within hydrocarbon-degrading electrogenic biofilms.

scholarly journals NADH dehydrogenases Nuo and Nqr1 contribute to extracellular electron transfer by Shewanella oneidensis MR-1 in bioelectrochemical systems

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Cody S. Madsen ◽  
Michaela A. TerAvest
Keyword(s):  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Growth Defect ◽  
Bioelectrochemical Systems ◽  
Terminal Electron Acceptor ◽  
Nadh Dehydrogenases ◽  
Level Of Understanding ◽  
High Level

Abstract Shewanella oneidensis MR-1 is quickly becoming a synthetic biology workhorse for bioelectrochemical technologies due to a high level of understanding of its interaction with electrodes. Transmembrane electron transfer via the Mtr pathway has been well characterized, however, the role of NADH dehydrogenases in feeding electrons to Mtr has been only minimally studied in S. oneidensis MR-1. Four NADH dehydrogenases are encoded in the genome, suggesting significant metabolic flexibility in oxidizing NADH under a variety of conditions. A strain lacking the two dehydrogenases essential for aerobic growth exhibited a severe growth defect with an anode (+0.4 VSHE) or Fe(III)-NTA as the terminal electron acceptor. Our study reveals that the same NADH dehydrogenase complexes are utilized under oxic conditions or with a high potential anode. Our study also supports the previously indicated importance of pyruvate dehydrogenase activity in producing NADH during anerobic lactate metabolism. Understanding the role of NADH in extracellular electron transfer may help improve biosensors and give insight into other applications for bioelectrochemical systems.

scholarly journals How Thermophilic Gram-Positive Organisms Perform Extracellular Electron Transfer: Characterization of the Cell Surface Terminal Reductase OcwA

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
N. L. Costa ◽  
B. Hermann ◽  
V. Fourmond ◽  
M. M. Faustino ◽  
M. Teixeira ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cell Surface ◽  
Electron Acceptors ◽  
Added Value ◽  
Extracellular Electron Transfer ◽  
Bioelectrochemical Systems ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Evolutionary Pathway ◽  
Structural And Functional Properties

ABSTRACT Extracellular electron transfer is the key process underpinning the development of bioelectrochemical systems for the production of energy or added-value compounds. Thermincola potens JR is a promising Gram-positive bacterium to be used in these systems because it is thermophilic. In this paper, we describe the structural and functional properties of the nonaheme cytochrome OcwA, which is the terminal reductase of this organism. The structure of OcwA, determined at 2.2-Å resolution, shows that the overall fold and organization of the hemes are not related to other metal reductases and instead are similar to those of multiheme cytochromes involved in the biogeochemical cycles of nitrogen and sulfur. We show that, in addition to solid electron acceptors, OcwA can also reduce soluble electron shuttles and oxyanions. These data reveal that OcwA can work as a multipurpose respiratory enzyme allowing this organism to grow in environments with rapidly changing availability of terminal electron acceptors without the need for transcriptional regulation and protein synthesis. IMPORTANCE Thermophilic Gram-positive organisms were recently shown to be a promising class of organisms to be used in bioelectrochemical systems for the production of electrical energy. These organisms present a thick peptidoglycan layer that was thought to preclude them to perform extracellular electron transfer (i.e., exchange catabolic electrons with solid electron acceptors outside the cell). In this paper, we describe the structure and functional mechanisms of the multiheme cytochrome OcwA, the terminal reductase of the Gram-positive bacterium Thermincola potens JR found at the cell surface of this organism. The results presented here show that this protein can take the role of a respiratory “Swiss Army knife,” allowing this organism to grow in environments with soluble and insoluble substrates. Moreover, it is shown that it is unrelated to terminal reductases found at the cell surface of other electroactive organisms. Instead, OcwA is similar to terminal reductases of soluble electron acceptors. Our data reveal that terminal oxidoreductases of soluble and insoluble substrates are evolutionarily related, providing novel insights into the evolutionary pathway of multiheme cytochromes.

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