Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction

Guillermo Pozo, Ludovic Jourdin, Yang Lu, Jürg Keller, Pablo Ledezma, Stefano Freguia

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14 Citations (Scopus)

Abstract

Recent evidence suggests that autotrophic sulfate reduction could be driven by direct and indirect electron transfer mechanisms in bioelectrochemical systems. However, much uncertainty still exists about the electron fluxes from the electrode to the final electron acceptor sulfate during autotrophic sulfate reduction. In this study, linear sweep voltammetry and chronamperometry coupled to off-gas measurement demonstrates that autotrophic sulfate reduction (0.9 ± 0.1 mol SO4 2−-S m2 d−1) is driven by electron fluxes from the cathode to sulfate via hydrogen as intermediate, with 95 ± 0.04% Coulombic efficiency towards sulfide production. Moreover, the biofilm-forming sulfate-reducing bacteria (SRBs) enriched on the cathode showed the remarkable ability to consume hydrogen at a rate of 3.9 ± 0.5 mol H2 m−2 d−1, outcompeting methanogens and homoacetogens for the hydrogen without the need to add chemical inhibitors. Furthermore, quantitative DAIME-FISH of the microbial communities in z-stack images confirmed that SRBs were more abundant (46.1 ± 3.9%) across the 16 ± 2 μm-thick biofilm than Methanobacteriales (13.9 ± 1.8%) and other bacteria (24.8 ± 2.6%) were. Finally, exposing the biofilm to biocidal conditions (pH 3.0, air drying and autoclaving) led to a 27% reduction of the hydrogen production rate, which was nevertheless 5.3 times higher than a bare electrode. Energy dispersive x-ray spectroscopy (EDS) and protein electrode surface analyses revealed the presence of metallic and proteinaceous materials deposited on the surface after biocidal conditions, suggesting that the biofilm was able to modify the electrode surface towards more efficient hydrogen evolution reaction (HER).

LanguageEnglish
Pages66-74
JournalElectrochimica Acta
Volume213
DOIs
Publication statusPublished - 2016

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Biofilms
Sulfates
Electrodes
Hydrogen
Bacteria
Electrons
Cathodes
Methanogens
Fluxes
Gas fuel measurement
Sulfides
Voltammetry
Hydrogen production
Energy dispersive spectroscopy
Drying
Spectroscopy
Proteins
X rays
Air

Cite this

Pozo, Guillermo ; Jourdin, Ludovic ; Lu, Yang ; Keller, Jürg ; Ledezma, Pablo ; Freguia, Stefano. / Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction. In: Electrochimica Acta. 2016 ; Vol. 213. pp. 66-74.
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abstract = "Recent evidence suggests that autotrophic sulfate reduction could be driven by direct and indirect electron transfer mechanisms in bioelectrochemical systems. However, much uncertainty still exists about the electron fluxes from the electrode to the final electron acceptor sulfate during autotrophic sulfate reduction. In this study, linear sweep voltammetry and chronamperometry coupled to off-gas measurement demonstrates that autotrophic sulfate reduction (0.9 ± 0.1 mol SO4 2−-S m2 d−1) is driven by electron fluxes from the cathode to sulfate via hydrogen as intermediate, with 95 ± 0.04{\%} Coulombic efficiency towards sulfide production. Moreover, the biofilm-forming sulfate-reducing bacteria (SRBs) enriched on the cathode showed the remarkable ability to consume hydrogen at a rate of 3.9 ± 0.5 mol H2 m−2 d−1, outcompeting methanogens and homoacetogens for the hydrogen without the need to add chemical inhibitors. Furthermore, quantitative DAIME-FISH of the microbial communities in z-stack images confirmed that SRBs were more abundant (46.1 ± 3.9{\%}) across the 16 ± 2 μm-thick biofilm than Methanobacteriales (13.9 ± 1.8{\%}) and other bacteria (24.8 ± 2.6{\%}) were. Finally, exposing the biofilm to biocidal conditions (pH 3.0, air drying and autoclaving) led to a 27{\%} reduction of the hydrogen production rate, which was nevertheless 5.3 times higher than a bare electrode. Energy dispersive x-ray spectroscopy (EDS) and protein electrode surface analyses revealed the presence of metallic and proteinaceous materials deposited on the surface after biocidal conditions, suggesting that the biofilm was able to modify the electrode surface towards more efficient hydrogen evolution reaction (HER).",
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Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction. / Pozo, Guillermo; Jourdin, Ludovic; Lu, Yang; Keller, Jürg; Ledezma, Pablo; Freguia, Stefano.

In: Electrochimica Acta, Vol. 213, 2016, p. 66-74.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Cathodic biofilm activates electrode surface and achieves efficient autotrophic sulfate reduction

AU - Pozo, Guillermo

AU - Jourdin, Ludovic

AU - Lu, Yang

AU - Keller, Jürg

AU - Ledezma, Pablo

AU - Freguia, Stefano

PY - 2016

Y1 - 2016

N2 - Recent evidence suggests that autotrophic sulfate reduction could be driven by direct and indirect electron transfer mechanisms in bioelectrochemical systems. However, much uncertainty still exists about the electron fluxes from the electrode to the final electron acceptor sulfate during autotrophic sulfate reduction. In this study, linear sweep voltammetry and chronamperometry coupled to off-gas measurement demonstrates that autotrophic sulfate reduction (0.9 ± 0.1 mol SO4 2−-S m2 d−1) is driven by electron fluxes from the cathode to sulfate via hydrogen as intermediate, with 95 ± 0.04% Coulombic efficiency towards sulfide production. Moreover, the biofilm-forming sulfate-reducing bacteria (SRBs) enriched on the cathode showed the remarkable ability to consume hydrogen at a rate of 3.9 ± 0.5 mol H2 m−2 d−1, outcompeting methanogens and homoacetogens for the hydrogen without the need to add chemical inhibitors. Furthermore, quantitative DAIME-FISH of the microbial communities in z-stack images confirmed that SRBs were more abundant (46.1 ± 3.9%) across the 16 ± 2 μm-thick biofilm than Methanobacteriales (13.9 ± 1.8%) and other bacteria (24.8 ± 2.6%) were. Finally, exposing the biofilm to biocidal conditions (pH 3.0, air drying and autoclaving) led to a 27% reduction of the hydrogen production rate, which was nevertheless 5.3 times higher than a bare electrode. Energy dispersive x-ray spectroscopy (EDS) and protein electrode surface analyses revealed the presence of metallic and proteinaceous materials deposited on the surface after biocidal conditions, suggesting that the biofilm was able to modify the electrode surface towards more efficient hydrogen evolution reaction (HER).

AB - Recent evidence suggests that autotrophic sulfate reduction could be driven by direct and indirect electron transfer mechanisms in bioelectrochemical systems. However, much uncertainty still exists about the electron fluxes from the electrode to the final electron acceptor sulfate during autotrophic sulfate reduction. In this study, linear sweep voltammetry and chronamperometry coupled to off-gas measurement demonstrates that autotrophic sulfate reduction (0.9 ± 0.1 mol SO4 2−-S m2 d−1) is driven by electron fluxes from the cathode to sulfate via hydrogen as intermediate, with 95 ± 0.04% Coulombic efficiency towards sulfide production. Moreover, the biofilm-forming sulfate-reducing bacteria (SRBs) enriched on the cathode showed the remarkable ability to consume hydrogen at a rate of 3.9 ± 0.5 mol H2 m−2 d−1, outcompeting methanogens and homoacetogens for the hydrogen without the need to add chemical inhibitors. Furthermore, quantitative DAIME-FISH of the microbial communities in z-stack images confirmed that SRBs were more abundant (46.1 ± 3.9%) across the 16 ± 2 μm-thick biofilm than Methanobacteriales (13.9 ± 1.8%) and other bacteria (24.8 ± 2.6%) were. Finally, exposing the biofilm to biocidal conditions (pH 3.0, air drying and autoclaving) led to a 27% reduction of the hydrogen production rate, which was nevertheless 5.3 times higher than a bare electrode. Energy dispersive x-ray spectroscopy (EDS) and protein electrode surface analyses revealed the presence of metallic and proteinaceous materials deposited on the surface after biocidal conditions, suggesting that the biofilm was able to modify the electrode surface towards more efficient hydrogen evolution reaction (HER).

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DO - 10.1016/j.electacta.2016.07.100

M3 - Article

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JO - Electrochimica Acta

T2 - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

ER -