Study reveals electron transport mechanism in cable bacteria's conductive nanoribbons
Researchers used density functional theory (DFT) calculations to model the electronic structure of nickel-organic nanoribbons found in cable bacteria, finding configurations that support efficient charge transport. Cable bacteria are unusual microorganisms capable of conducting electricity across centimeter-scale distances through protein fiber networks, a phenomenon whose molecular mechanism has remained poorly understood. The findings suggest that stacked nickel bis(1,2-dithiolene) units in specific packing arrangements could explain the exceptionally high conductivities measured in these biological fibers.
A new computational study posted to arXiv examines the molecular architecture of conductive nanoribbons embedded in the cell envelope fibers of cable bacteria, organisms known for their remarkable ability to transport electrons over centimeter-scale distances. Using DFT calculations, the researchers modeled how nickel bis(1,2-dithiolene) (NiBiD) units stack together, identifying AA- and AB-type packing configurations as the most plausible structures. The energetically most stable AB-type arrangement features five-fold coordination at some nickel centers due to inter-layer nickel-sulfur bonding, a structural detail with potential implications for charge delocalization. Critically, several low-energy configurations show electronic coupling between neighboring molecules that exceeds the threshold required for charge delocalization, meaning electron transport could proceed beyond the slower small polaron hopping mechanism. This would be consistent with the unusually high conductivities—rivaling the best synthetic conductive polymers—observed experimentally in cable bacteria fibers. The study provides a theoretically grounded mechanistic explanation for a longstanding puzzle in microbial biophysics and electrochemistry.
What's missing
As a computational preprint, the study has not yet undergone peer review. The authors do not address how environmental factors such as pH, redox state, or hydration within the cell envelope might alter the predicted electronic properties.
What different sources said
- arXiv physicsCenter
Model structures and electron transfer properties of conductive nickel-organic nanoribbons in cable bacteria
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