Bacteria create electrical grids to share energy

Electrogenic bacteria wired up with pili

Earlier work (2011) has shown that bacteria can be used to extract hydrogen from water with an efficiency of 58-64%. Bacteria-enabled reverse-electrodialysis (BERED).

Now comes news that they can wire up their own electrical grids:

Japanese researchers have found that two species of bacteria can use minerals in the soil to transfer electrons over long distances, according to research published today (June 4) in Proceedings of the National Academy of Sciences. This creates currents between the species, and turns them into living electrical grids, allowing them to cooperate in breaking down chemicals in their environment that they could not metabolise individually.

hat tip to Ed Yong’s article in The Scientist

We know they share genes, now we know they share electricity.

Recall that electron relays are foundational to life’s chemistry. Metabolism is fueled by ripping electrons from food and donating them to oxygen. Bacteria can perform such transfer between cells/individuals, and even across species (leaky processes, black queen, gene transfer, …). This is know to occur via direct cell-to-cell contact.

The new finding is evidence to show that ferrous compounds in soil/sediment allow longer-range electron sharing. Further note that some bacteria (Geobacter sulfurreducens, for one) can produce magnetite nanoparticles– they can create their own “wires”.

Article abstract and citation info:

In anaerobic biota, reducing equivalents (electrons) are transferred between different species of microbes [interspecies electron transfer (IET)], establishing the basis of cooperative behaviors and community functions. IET mechanisms described so far are based on diffusion of redox chemical species and/or direct contact in cell aggregates. Here, we show another possibility that IET also occurs via electric currents through natural conductive minerals. Our investigation revealed that electrically conductive magnetite nanoparticles facilitated IET from Geobacter sulfurreducens to Thiobacillus denitrificans, accomplishing acetate oxidation coupled to nitrate reduction. This two-species cooperative catabolism also occurred, albeit one order of magnitude slower, in the presence of Fe ions that worked as diffusive redox species. Semiconductive and insulating iron-oxide nanoparticles did not accelerate the cooperative catabolism. Our results suggest that microbes use conductive mineral particles as conduits of electrons, resulting in efficient IET and cooperative catabolism. Furthermore, such natural mineral conduits are considered to provide ecological advantages for users, because their investments in IET can be reduced. Given that conductive minerals are ubiquitously and abundantly present in nature, electric interactions between microbes and conductive minerals may contribute greatly to the coupling of biogeochemical reactions.

S. Kato et al., “Microbial interspecies electron transfer via electric currents through conductive minerals,” Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1117592109, 2012.


Posted on June 5, 2012, in evolution and tagged , . Bookmark the permalink. Leave a comment.

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