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Updated: Jun 2, 2025
08:52
Characterizing Electron Transport through Living Biofilms
Published on: June 1, 2018
8.4K
Hydrated cable bacteria exhibit protonic conductivity over long distances.
Bradley G Lusk1,2, Sheba Morgan3, Shawn P Mulvaney4
1Science the Earth, Mesa, AZ 85201.
Summary
Cable bacteria, filamentous microorganisms, conduct protons over long distances (>100 µm) via proton wires. Their protonic conductivity is highly dependent on relative humidity, suggesting Grotthuss mechanism transport.
Area of Science:
- Microbiology
- Biophysics
- Electrochemistry
Background:
- Filamentous microorganisms known as cable bacteria (Desulfobulbaceae) are recognized for their electrical conductivity.
- Their capacity for long-distance electron transfer has significant implications for microbial ecosystems.
Purpose of the Study:
- To directly measure and characterize proton transport along cable bacteria.
- To investigate the mechanisms and environmental dependencies of proton conduction in these microorganisms.
Main Methods:
- Utilized a modified transfer-printing technique to deposit palladium (interdigitated protodes, transfer length method) and gold (interdigitated electrodes) on cable bacteria.
- Measured protonic conductivity (σ) and conductance (G) under varying relative humidity (RH) conditions.
Main Results:
- Demonstrated that cable bacteria function as protonic conduits, transporting protons over distances greater than 100 µm.
- Measured protonic conductivity as high as 114 ± 28 µS cm⁻¹ at 25 °C and 70% RH.
- Observed a 26-fold increase in protonic conductance and conductivity between 60% and 80% RH, indicating Grotthuss mechanism involvement.
Conclusions:
- Cable bacteria possess proton wires enabling long-distance proton transport.
- Proton transport is strongly influenced by relative humidity, suggesting a water-mediated Grotthuss mechanism.
- Findings open avenues for exploring proton transport in microbial ecosystems and developing biomimetic proton-mediated interfaces.
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