Charge Injection and Interfiber Electrical Conduction in Cable Bacteria

Area of Science:

• Microbiology
• Biophysics
• Bioelectronics

Background:

• Cable bacteria are multicellular microorganisms with conductive fibers enabling long-distance charge transport.
• Understanding charge injection is crucial for their application in biobased electronics.

Purpose of the Study:

• To investigate the charge injection mechanism into cable bacteria conductive fibers.
• To isolate and characterize charge transfer between contacting bacterial filaments.

Main Methods:

• Fabrication of "crosses" using native bacteria or extracted fiber skeletons.
• Probing charge transport through individual filaments and cross-cable configurations.
• Temperature-dependent characterization from 300 K down to 50 K.

Main Results:

• Charge transfer between contacting cable bacterium fibers is feasible, though with increased resistance.
• Thermally activated Arrhenius behavior was observed for both single filaments and cross-conduction.
• Activation energy for filament-to-filament transport (15–40 meV) was slightly lower than for individual filaments.

Conclusions:

• Charge injection into cable bacterium fibers utilizes the same mechanism as charge transport along them.
• A structural model proposes internally winding conductive channels within a protein matrix, enabling external electrical contact.