Effect of electrode spacing on electron transfer and conductivity of Geobacter sulfurreducens biofilms

Panpan Liu; Abdelrhman Mohamed; Peng Liang; Haluk Beyenal

doi:10.1016/j.bioelechem.2019.107395

Effect of electrode spacing on electron transfer and conductivity of Geobacter sulfurreducens biofilms

Bioelectrochemistry. 2020 Feb:131:107395. doi: 10.1016/j.bioelechem.2019.107395. Epub 2019 Oct 4.

Authors

Panpan Liu¹, Abdelrhman Mohamed², Peng Liang³, Haluk Beyenal⁴

Affiliations

¹ State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment, Tsinghua University, Beijing 100084, PR China; The Gene and Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99163, USA.
² The Gene and Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99163, USA.
³ State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment, Tsinghua University, Beijing 100084, PR China.
⁴ The Gene and Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99163, USA. Electronic address: beyenal@wsu.edu.

PMID: 31704456
DOI: 10.1016/j.bioelechem.2019.107395

Abstract

To understand electron transport in electrochemically active biofilms, it is necessary to elucidate the heterogeneous electron transport across the biofilm/electrode interface and in the interior of G. sulfurreducens biofilms bridging gaps of varying widths. The conductivity of Geobacter sulfurreducens biofilm bridging nonconductive gaps with widths of 5µm, 10µm, 20µm and 50µm is investigated. Results of electrochemical gating measurement show that biofilm conductivity peaks at the potential of -0.35V vs. Ag/AgCl. The biofilm conductivity increases with gap width (10.4±0.2µScm^-1 in 5µm gap, 13.3±0.2µScm^-1 in 10µm gap, 16.7±1.4µScm^-1 in 20µm gap and 41.8±2.02µScm^-1 in 50µm gap). These results revealed that electron transfer in G. sulfurreducens biofilm is a redox-driven. In addition, higher biofilm conductivities and lower charge transfer resistances are observed in all gaps under a turnover condition than in those under a non-turnover condition. Our results offer insights into the spatial heterogeneity of biofilm structure and extracellular electron transfer in electrochemically active biofilms.

Keywords: Biofilm conductivity; Electrochemically active biofilm; Exoelectrogens; Extracellular electron transfer; Microbial electrochemistry and spatial heterogeneity.

MeSH terms

Biofilms*
Electric Conductivity*
Electrodes*
Electron Transport
Geobacter / metabolism*