Cable bacteria usually form centimetre long filaments as they consist of thousands of cells end-to-end to couple sulfide oxidization in anoxic sediment and oxygen reduction at the sediment surface in aquatic systems 7, 12, 13. These protein nanowires can form conductive networks and contribute to direct intercellular electron transfer in biofilms or aggregates composed of different microorganisms 9, 10, 11. Conductive protein nanowires generated by Geobacter and several other microorganisms can transfer electrons over tens of micrometer 4, 5, 6.

Two bacterial LDET strategies have been identified: conductive protein nanowires generated by relatively short, unicellular bacteria (e.g., Geobacter species) and conductive envelopes formed by filamentous, multicellular cable bacteria 4, 8. Some single-celled bacteria are capable of long-distance electron transfer (LDET) to chemicals or other microbial cells at tens of micrometers distance 4, 5, 6 and multicellular cable bacteria transport electrons in the range of centimetres 7, 8. In addition to respiration with intracellular chemicals such as oxygen, sulfate, or nitrate, bacteria can also respire with externally accessed chemicals such as mineral particles (i.e., extracellular electron transfer, EET) 1, 2, 3. Bacteria are versatile in their ability to transfer electrons to various chemicals and to preserve energy. Electron transfer is essential for energy generation and the metabolism of life.

Nanoscope analysis 1.9 free download