‘Candidatus Tenderia electrophaga', an uncultivated electroautotroph from a biocathode enrichment

Eddie, Brian J.; Wang, Zheng; Malanoski, Anthony P.; Hall, Richard J.; Oh, Steve D.; Heiner, Cheryl; Lin, Baochuan; Glaven, Sarah M.

doi:10.1099/ijsem.0.001006

Cited by 50 publications

(38 citation statements)

References 32 publications

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“…This catalytic behavior is believed to be due to the activity of uncultured Gammaproteobacteria , , which likely gain energy for metabolism and growth by using electrons derived directly from the electrode, simultaneously catalyzing the ORR . Recently, a putative electron transport chain involving extracellular electron transfer for the electroautotroph ‘ Candidatus Tenderia electrophaga' was proposed based on metagenomics , metaproteomics , and metatranscriptomics studies . The findings suggest that electrons are accepted from the cathode electrode via an outer‐membrane bound cytochrome, similar to Cyc2 in iron oxidizing bacteria, and are utilized in downhill and uphill electron transport pathways , .…”

Section: Resultsmentioning

confidence: 99%

The Effect of Oxygen Mass Transfer on Aerobic Biocathode Performance, Biofilm Growth and Distribution in Microbial Fuel Cells

Milner

2018

Fuel Cells

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Microbial fuel cells (MFCs) are a sustainable technology for the direct conversion of biodegradable organics in wastewater into electricity. In most MFCs, the oxygen reduction reaction (ORR) is used as the cathode reduction reaction. Aerobic biocathodes, which use bacteria as biocatalysts to catalyze the cathode ORR, provide self‐sustained, robust and highly active alternatives to chemical catalysts. However, further study of the effect of oxygen mass transfer to the biofilm and cathode materials design is needed. In the current work, two aerobic biocathodes were enriched in half‐cells, and oxygen mass transfer to the biofilm and the biofilm distribution in the porous electrode structure were investigated. It was found that mass transfer of oxygen to the aerobic biocathode was a significant factor affecting cathode ORR, evidenced by a strong correlation between the air flow rate and current. Additionally, it was found that the biofilm penetrates between 20–30% into the porous carbon electrode structure, which is likely due to oxygen mass transfer limitations. The performance of a MFC with biocatalysts at both anode and cathode (64 µW cm−2 peak power at an air flowrate of 1 L min−1) showed strong correlation with air flowrate, confirming the observation in the half‐cell system.

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Section: Resultsmentioning

confidence: 99%

The Effect of Oxygen Mass Transfer on Aerobic Biocathode Performance, Biofilm Growth and Distribution in Microbial Fuel Cells

Milner

2018

Fuel Cells

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“…However, the major constituents that are present have been stable for over 6 years, as measured by several methods, including the use of 16S clone libraries, metagenomics, proteomics, 16S amplicon sequencing, and fluorescence in situ hybridization microscopy (9, 10, 13, 19, 20), allowing us to use the previously generated metagenome sequencing data to align the metatranscriptomics data. This is important for studies where only limited biomass can be recovered from the electrode surface.…”

Section: Discussionmentioning

confidence: 99%

“…Previous metagenomic and proteomics studies of MCL have led to the identification of putative EET and CO 2 fixation mechanisms (13, 19), although efforts at cultivation have not yielded the proposed electroautotroph, “ Candidatus Tenderia electrophaga” (20). Other work has resulted in isolates from aerobic biocathode enrichments, but these have not been autotrophic (21, 22).…”

Section: Introductionmentioning

confidence: 99%

Metatranscriptomics Supports the Mechanism for Biocathode Electroautotrophy by “CandidatusTenderia electrophaga”

et al. 2017

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Bacteria that directly use electrodes as metabolic electron donors (biocathodes) have been proposed for applications ranging from microbial electrosynthesis to advanced bioelectronics for cellular communication with machines. However, just as we understand very little about oxidation of analogous natural insoluble electron donors, such as iron oxide, the organisms and extracellular electron transfer (EET) pathways underlying the electrode-cell direct electron transfer processes are almost completely unknown. Biocathodes are a stable biofilm cultivation platform to interrogate both the rate and mechanism of EET using electrochemistry and to study the electroautotrophic organisms that catalyze these reactions. Here we provide new evidence supporting the hypothesis that the uncultured bacterium “Candidatus Tenderia electrophaga” directly couples extracellular electron transfer to CO2 fixation. Our results provide insight into developing biocathode technology, such as microbial electrosynthesis, as well as advancing our understanding of chemolithoautotrophy.

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“…Marinobacter atlanticus strain CP1 was recently isolated from the Biocathode MCL community, named for the three most abundant members: Marinobacter, an uncharacterized member of the Chromatiaceae, and Labrenzia (Wang et al, 2015b;Bird et al, 2018). The Biocathode MCL community was originally enriched from seawater at 310 mV vs. SHE and is proposed to catalyze electron transfer from an electrode to oxygen and carbon dioxide for growth due to the activity of the uncharacterized Chromatiaceae [renamed "Candidatus Tenderia electrophaga" (Eddie et al, 2016)]. "Ca.…”

Section: Marinobactermentioning

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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‘Candidatus Tenderia electrophaga', an uncultivated electroautotroph from a biocathode enrichment

Cited by 50 publications

References 32 publications

The Effect of Oxygen Mass Transfer on Aerobic Biocathode Performance, Biofilm Growth and Distribution in Microbial Fuel Cells

The Effect of Oxygen Mass Transfer on Aerobic Biocathode Performance, Biofilm Growth and Distribution in Microbial Fuel Cells

Metatranscriptomics Supports the Mechanism for Biocathode Electroautotrophy by “CandidatusTenderia electrophaga”

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

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