Tactic Response of Shewanella oneidensis MR-1 toward Insoluble Electron Acceptors

Oram, Joseph; Jeuken, Lars J. C.

doi:10.1128/mbio.02490-18

Cited by 18 publications

(13 citation statements)

References 18 publications

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“…These electricigens naturally transfer electrons to an electrode in three ways: (i) electron transfer via bacteria-produced redox-active molecules (electron shuttles), (ii) short-range direct electron transfer between cytochromes on the outer membrane and the electrode; and (iii) long-range electron transport through conductive biofilms consisting of an extracellular matrix and motility apparatus (i.e., pili and filament) [1]. Besides, extracellular electron transfer efficiency is dependent on the ability of bacteria to migrate toward and colonize insoluble electron acceptors (electrodes) [5].…”

Section: Introductionmentioning

confidence: 99%

Bioelectricity Generation by Corynebacterium glutamicum with Redox-Hydrogel-Modified Carbon Electrode

et al. 2019

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This work studied Gram-positive and weak electricigen Corynebacterium glutamicum for its ability to transfer electrons and to produce bioelectricity in microbial fuel cells (MFCs). The electrochemical and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) results revealed that C. glutamicum had the potential to mediate electron transfer to an electrode by emitting its own extracellular electron shuttles such as flavins. To enhance the current collection from C. glutamicum, a carbon cloth anode was modified with ferrocene-branched chitosan hydrogel (redox-hydrogel). The maximum current density of the ferrocene-branched chitosan redox hydrogel anode with C. glutamicum was drastically increased to 120 µA cm−2 relative to a bare carbon cloth electrode with C. glutamicum (261 nA cm−2). The power density and polarization curves for the MFC operation with the redox-hydrogel-modified anode showed that C. glutamicum effectively generated bioelectricity by means of the redox-hydrogel anode. The results suggest that, in such an electro-fermentation process, ferrocene-branched chitosan hydrogel grafted onto an anode surface would also facilitate both electron transfer from C. glutamicum to the anode and bioelectricity generation.

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Section: Introductionmentioning

confidence: 99%

Bioelectricity Generation by Corynebacterium glutamicum with Redox-Hydrogel-Modified Carbon Electrode

et al. 2019

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“…Other work, however, has suggested a role for redox‐active flavins in taxis to insoluble acceptors (Li et al, 2012; Oram & Jeuken, 2019). As mentioned previously, FMN and riboflavin are likely to be attractants for S. oneidensis .…”

Section: Taxis In S Oneidensismentioning

confidence: 99%

“…If driven by energy taxis, S. oneidensis may sense changes in the magnitude of the proton motive force or the redox state in the electron transport chain, as with Aer in E. coli , that occur upon flavin reduction (Ortega et al, 2020; Samanta et al, 2016). Recently, work by Oram and Jeuken has also indirectly pointed to flavins as mediators of taxis to electrodes (Oram & Jeuken, 2019). In capillary electrode experiments, average cell velocity and the number of motile cells within 20 μm of the electrode was measured as a function of the electrode potential.…”

Section: Taxis In S Oneidensismentioning

confidence: 99%

Electrolocation? The evidence for redox‐mediated taxis in Shewanella oneidensis

Starwalt-Lee

El‐Naggar

Bond

et al. 2020

Molecular Microbiology

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Shewanella oneidensis is a dissimilatory metal reducing bacterium and model for extracellular electron transfer (EET), a respiratory mechanism in which electrons are transferred out of the cell. In the last 10 years, migration to insoluble electron acceptors for EET has been shown to be nonrandom and tactic, seemingly in the absence of molecular or energy gradients that typically allow for taxis. As the ability to sense, locate, and respire electrodes has applications in bioelectrochemical technology, a better understanding of taxis in S. oneidensis is needed. While the EET conduits of S. oneidensis have been studied extensively, its taxis pathways and their interplay with EET are not yet understood, making investigation into taxis phenomena nontrivial. Since S. oneidensis is a member of an EET‐encoding clade, the genetic circuitry of taxis to insoluble acceptors may be conserved. We performed a bioinformatic analysis of Shewanella genomes to identify S. oneidensis chemotaxis orthologs conserved in the genus. In addition to the previously reported core chemotaxis gene cluster, we identify several other conserved proteins in the taxis signaling pathway. We present the current evidence for the two proposed models of EET taxis, “electrokinesis” and flavin‐mediated taxis, and highlight key areas in need of further investigation.

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“…Therefore, we conclude that riboflavin is being secreted by S. oneidensis for a purpose beyond acting as an electron mediator itself. There is evidence that S. oneidensis also uses riboflavin as a signaling molecule, where riboflavin activates the cells for a number of different cellular behaviors, including repulsion of foreign bodies (Moriyama et al, 2008;Brutinel et al, 2013) or chemotaxis of other S. oneidensis bacteria (Li et al, 2012;Kim et al, 2016;Oram and Jeuken, 2019). To elucidate the purpose of FIGURE 2 | Viability of S. oneidensis exposed to nano-PS as measured with a growth-based viability assay.…”

Section: Riboflavin Secretionmentioning

confidence: 99%

“…The metal reduction function is facilitated through the secretion of flavin mediators, including riboflavin and flavin mononucleotide. Riboflavin secretion is a critical cell function of S. oneidensis, serving as both an electron mediator in anaerobic respiration and as a signaling molecule when the bacteria are under stress in both aerobic and anaerobic environments (Brutinel et al, 2013;Oram and Jeuken, 2019). Finally, this model organism has been used in previous nanoparticle toxicity assessments and thus provides precedent benchmarks for toxicity responses that go beyond only live versus dead cell counts, with evaluation of how substances induce changes of cellular function and gene expression (Maurer-Jones et al, 2013a,c;Zhi et al, 2019;Buchman et al, 2020;Clement et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Impacts of Nanoplastics on the Viability and Riboflavin Secretion in the Model Bacteria Shewanella oneidensis

Fringer

Fawcett

Mitrano

et al. 2020

Front. Environ. Sci.

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Characterizing the impact of nanoplastics to organism health is important to understand the consequences of the environmental plastic waste problem. This article examines the impact of nano-polystyrene (nano-PS; 159 ± 0.9 nm diameter) to ecologically relevant bacteria Shewanella oneidensis. Bacterial viability was evaluated using a growth-based assay. Riboflavin secretion is a critical cell function of S. oneidensis, serving as an electron mediator in anaerobic respiration and/or as a signaling molecule when the bacteria are under stress. Thus, changes in cellular function were monitored through riboflavin secretion in order to evaluate toxic responses that may not result in cell death. Under aerobic and anaerobic exposures (4, 8, or 12 h), the viability of the S. oneidensis was minimally changed as compared to the control, while the concentration of riboflavin secreted varied with exposure dose. In order to determine if this was a specific response to nanoplastic particles, opposed to a response to either particles or plastic more generally, we exposed the system to colloidal TiO 2 nanoparticles and polystyrene and polyethylene thin films. We confirmed that riboflavin secretion trends were specific to nano-PS and not to these other materials, which showed no significant changes. We investigated the association of the nano-PS with ICP-MS using Pd that was chemically incorporated into the model nanoplastics. While 59.2% of the nano-PS were found in the non-cellular culture media, 7.0 and 6.6% was found associated with the loosely and tightly bound extracellular polymeric substance, respectively. There was significantly more nano-PS (10.9%) strongly associated with the cells. Taken together, we found that nano-PS had minimal impacts to viability but caused a significant change in the function of S. oneidensis that can be related to the nano-PS attached or in proximity to the bacterium. These trends are consistent between aerobic and anaerobic cultures, signifying that the stress response of S. oneidensis can be generalized between different environmental compartments. This work highlights that the association of nanoplastic materials with microorganisms may modify the cellular function that could ultimately be an impact to ecosystem health.

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Tactic Response of Shewanella oneidensis MR-1 toward Insoluble Electron Acceptors

Cited by 18 publications

References 18 publications

Bioelectricity Generation by Corynebacterium glutamicum with Redox-Hydrogel-Modified Carbon Electrode

Bioelectricity Generation by Corynebacterium glutamicum with Redox-Hydrogel-Modified Carbon Electrode

Electrolocation? The evidence for redox‐mediated taxis in Shewanella oneidensis

Impacts of Nanoplastics on the Viability and Riboflavin Secretion in the Model Bacteria Shewanella oneidensis

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