Weak electricigens: A new avenue for bioelectrochemical research

Doyle, Lucinda Elizabeth; Marsili, Enrico

doi:10.1016/j.biortech.2018.02.073

Cited by 115 publications

(79 citation statements)

References 142 publications

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“…This premise is consistent with a low coulombic efficiency value estimated on the basis of current production and electron donor substrate consumption, i. e., 1000‐fold lesser than the number of electrons generated from glucose and lactate (considering glycolysis of glucose and lactate oxidation to pyruvate) in P. gingivalis and A. actinomycetemcomitans respectively (Figure S3). Compared to environmental EET‐capable bacteria such as Shewanella oneidensis MR1, Geobacter sulfurreducens PCA, these current densities are lower as observed in our study and in a few other reported pathogens termed as weak electricigens . The export of electrons would facilitate the fermentation reactions instead of accumulating the reductive energy inside the cells …”

Section: Resultscontrasting

confidence: 56%

Electrochemical Characterization of Current‐Producing Human Oral Pathogens by Whole‐Cell Electrochemistry

et al. 2020

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Extracellular electron transfer (EET) via cell-bound redox enzymes and/or redox shuttles is extensively studied in environmental bacteria. Meanwhile, EET capable pathogens have been identified in the human gut. However, other EET-capable bacterial niches where possible biofilm infections are prominent have scarcely been explored. Herein, we electrochemically characterized human oral biofilm pathogens, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, to examine their EET capability. Both strains showed current production with the electrode poised at + 0.4 V vs. a standard hydrogen electrode, which was associated with a decrease in electrondonor concentration, coupled with the appearance of oxidative peaks in differential pulse (DP) and cyclic voltammograms (CV).Addition of antibiotics that suppress the biosynthesis of membrane or protein showed a significant current decrease, demonstrating that current production reflects the cellular activity in these pathogens. DPV-and CV-based kinetic analyses supported by transmission electron microscopy of the cells stained for transition metals suggest a potential EET mechanism associated with the presence of redox enzymes on the cell membrane. These results could be the basis to reevaluate human oral pathogens from an electroactive point of view. The identified electrochemical activity of the two strains can be an effective test for assessing the impact of antibacterial compounds on the pathogen cellular activity on an electrode. cell secreted metabolites of the preculture medium ( Figure S1). Cell cultures were handled in COY anaerobic chamber filled with 100 % N 2 . DM was prepared according to previously described methods [32] with some modification. DM contained (per liter) the following Figure 3. Transmission electron microscopy (TEM) of 3,3'-diaminobenzidene (DAB)-stained cells of Aggregatibacter actinomycetemcomitans (AA) and Porphyromonas gingivalis (PG). Positive DAB staining with the addition of H 2 O 2 (a, c), and negative DAB staining in the absence of H 2 O 2 (b, d). Scale bars, 50 nm. DAB-stained layer thickness (e) and absorption (f) of A. actinomycetemcomitans and P. gingivalis measured from (n = 10) line profiles of TEM images under DAB-positive and -negative conditions. ChemElectroChemArticles A stock solution of Sodium Ampicillin 1.86 g/L was prepared, and the stock solution was added into the electrochemical reactor to a final concentration about 1 mg/mL. This is higher than the minimum inhibitory concentration and minimum bactericidal concentration for both planktonic and electrode-attached cells. [27] A stock solution of 50 mg/mL Kanamycin (Sigma-Aldrich) was added to a final concentration of 1 mg/mL.

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Section: Resultscontrasting

confidence: 56%

Electrochemical Characterization of Current‐Producing Human Oral Pathogens by Whole‐Cell Electrochemistry

et al. 2020

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“…However, it is still unclear if microbially‐produced flavins contribute to EET in cytochrome‐bound rather than in free form . These and other examples, recently reviewed by our group suggest that both DET and MET contribute to overall EET in mixed microbial consortia.…”

Section: Introductionmentioning

confidence: 76%

Electrochemical Signature of Escherichia coli on Nickel Micropillar Array Electrode for Early Biofilm Characterization

Astorga

Marsili

et al. 2019

ChemElectroChem

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Biofilms are sessile microbial communities living at interfaces, in which the extracellular matrix is responsible for the mechanical stability and adhesion to surfaces. Transition from planktonic to attached cells is a key step in the biofilm formation process. Monitoring of this transition is needed to prevent contamination of biomedical devices and mitigate microbially influenced corrosion. Under anoxic local conditions and in the presence of an exogenous redox mediator, biofilms can divert part of the electron flow associated with catabolism to electrodes maintained at a defined potential. Extracellular electron transfer (EET) follows upon the attachment of planktonic cells to the surface. Modification of the electrode increases bacterial attachment, thus allowing early bioelectrochemical detection of the biofilm. Here, we report a Ni electrode micropillar array to detect early attachment of Escherichia coli biofilm through mediated EET in potentiostat‐controlled electrochemical cells. The biofilm‐surface interaction is studied by using electrochemical impedance spectroscopy (EIS) at different potentials and temperatures over 24 h. The analysis of the EIS signature highlights the effect of temperature on mediated EET in biofilms. These results demonstrate that micropillared electrodes allow earlier biofilm detection than flat electrodes, which is relevant to biofilm sensing and investigation of microbially influenced corrosion in drinking water systems and biomedical devices.

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“…Here we demonstrated that M. atlanticus is able to generate very low levels of anodic and cathodic current, an indicator of its ability to perform EET outside of the Biocathode MCL community. Constituents of electrochemically active microbial communities that produce low levels of current on their own should not be discounted and may have important roles for the function of the community as a whole (Doyle and Marsili, 2018). Anodic current can be enhanced at 310 mV through addition of riboflavin and excess minerals.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Characterization of Marinobacter atlanticus Strain CP1 Suggests a Role for Trace Minerals in Electrogenic Activity

Onderko¹,

Phillips²,

Eddie³

et al. 2019

Front. Energy Res.

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The marine heterotroph, Marinobacter atlanticus strain CP1, was recently isolated from the electroautotrophic Biocathode MCL community, named for the three most abundant members: Marinobacter, an uncharacterized member of the Chromatiaceae, and Labrenzia. Biocathode MCL catalyzes the production of cathodic current coupled to carbon fixation through the activity of the uncharacterized Chromatiaceae, renamed as "Candidatus Tenderia electrophaga," but the contribution of M. atlanticus is currently unknown. Here, we report on the electrochemical characterization of pure culture M. atlanticus biofilms grown under aerobic conditions and supplemented with succinate as a carbon source at applied potentials ranging from 160 to 510 mV vs. SHE, and on three different electrode materials (graphite, carbon cloth, and indium tin oxide). M. atlanticus was found to produce either cathodic or anodic current that was an order of magnitude lower than that of the Biocathode MCL community depending on the oxygen concentration, applied potential, and electrode material. Cyclic voltammetry, differential pulse voltammetry (DPV), and square wave voltammetry (SWV) were performed to characterize putative redox mediators at the electrode surface; however no definitive redox peaks were observed. No effect on current was observed when genes encoding a putative rubredoxin (ACP86_RS07295), as well as a putative NADH:flavorubredoxin oxidoreductase (ACP86_RS07290), were deleted to evaluate their role in EET. The addition of either riboflavin or excess trace mineral solution increased anodic current by ca. an order of magnitude under the conditions in which Biocathode MCL is typically grown. These results indicate that M. atlanticus has a non-negligible ability to utilize electrodes as an electron acceptor, which can be enhanced by the presence of excess trace minerals already available in the growth medium. The ability of M. atlanticus to utilize trace minerals as electron shuttles with extracellular electron acceptors may have broader implications for its natural role in biogeochemical cycling.

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Weak electricigens: A new avenue for bioelectrochemical research

Cited by 115 publications

References 142 publications

Electrochemical Characterization of Current‐Producing Human Oral Pathogens by Whole‐Cell Electrochemistry

Electrochemical Characterization of Current‐Producing Human Oral Pathogens by Whole‐Cell Electrochemistry

Electrochemical Signature of Escherichia coli on Nickel Micropillar Array Electrode for Early Biofilm Characterization

Electrochemical Characterization of Marinobacter atlanticus Strain CP1 Suggests a Role for Trace Minerals in Electrogenic Activity

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