Charge Injection and Interfiber Electrical Conduction in Cable Bacteria

ACS Applied Materials & Interfaces, vol. 18, pp. 25038–25043

Abstract

Cable bacteria are multicellular microorganisms capable of charge transport over centimeter-scale distances through a network of conductive fibers embedded in the cell envelope. Understanding the charge injection mechanism into these fibers is essential to obtain a complete picture of their long-distance charge transport and a crucial step for their application in biobased electronics. To this aim, we fabricated "crosses" of two filaments, either native bacteria or extracted fiber skeletons, placed one on top of each other. By probing charge transport both through individual filaments and in cross-cable configurations, i.e., with current flowing from one filament to the other, it is possible to isolate the charge injection contribution. The results indicate that charge transfer between two contacting fibers is possible, albeit with increased resistance. We characterized the crosses at different temperatures, from 300 down to 50 K, observing thermally activated Arrhenius behavior both for single filaments and cross-conduction. The corresponding activation energy for filament-to-filament transport ranged from 15 to 40 meV, slightly smaller than that of individual cable bacterium filaments. We conclude that charge injection into the fibers must rely on the same mechanism as charge transport along the fibers. A structural model of the fibers is proposed in which internally winding conductive channels are embedded in a protein matrix. These channels can locally reach the surface of the fibers, where they can establish electrical contact with the external environment.

Authors 6

1. Cosimo Tommasi corresponding

   Kavli Nanoscience Institute · Delft University of Technology

   Affiliation as printed

   Delft University of Technology

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience

2. Anastasia Gerzhik Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Faculty I

   Forschungszentrum Jülich

   Institute of Biological Information Processing, Bioelectronics (IBI-3)

   RWTH Aachen University

3. Silvia Hidalgo‐Martinez

   University of Antwerp

   Affiliation as printed

   Department of Biology

   University of Antwerp

4. Dirk Mayer

   Forschungszentrum Jülich

   Affiliation as printed

   Forschungszentrum Jülich

   Institute of Biological Information Processing, Bioelectronics (IBI-3)

5. Filip J. R. Meysman

   University of Antwerp · Delft University of Technology

   Affiliation as printed

   Delft University of Technology

   Department of Biology

   Department of Biotechnology

   University of Antwerp

6. Herre S. J. van der Zant corresponding

   Kavli Nanoscience Institute · Delft University of Technology

   Affiliation as printed

   Delft University of Technology

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience