Bacteria can carry electrical currents and can use electricity for power. An international team of scientists has now found that bacteria can act like power lines, and send electrical currents over long distances. Microbes that live on the seafloor and are only a centimeter in length can form a conductive network that is like the copper wiring that carries the electricity we use. These conductive fibers could bring electronics and biology together in a new way, and create different kinds of materials and technologies.
“The use of biomaterials in electronic engineering is an active field of research, for example, to achieve biodegradable electronics, which could reduce the problem of e-waste and allow greener consumer electronics, or they could be applied in health care, where implantable diagnostic and therapeutic devices could function during a certain time frame and then disappear via resorption by the body,” explained Professor Filip Meysman of the University of Antwerp. “Maybe within some years, we will have medical implants or smartphones that are equipped with minuscule conducting wires of bacterial origin.”
Cable bacteria are made up of thousands of microbial cells. “These multicellular bacteria were only discovered a few years ago, and we already knew they were doing something exceptional,” Meysman noted.
Research showed that electrical currents observed on the seafloor were being generated by these microbes, he explained. “Such an electricity-based metabolism would give the cable a huge advantage, being able to harvest energy from deeper layers within the seafloor,” he added.
In this work, the researchers isolated one bacterial filament from the seafloor and managed to attach electrodes to it (though it’s far thinner than a human hair). “It took us great effort to connect the bacteria,” commented Professor Herre van der Zant, a physicist from the Delft University of Technology. “But when we finally succeeded, the results were baffling. We saw that there was a large current going through this thin cable bacterium.”
After tweaking their methods, they demonstrated that currents could flow through a filament that was over one centimeter long. “This extends the known length scale of biological electron transport by orders of magnitude and implies that cable bacteria have found a mechanism to efficiently transport charges over centimeter-scale distances,” said Professor Jean Manca of the University of Hasselt.
The researchers investigated the structures in the bacteria that were sustaining these high currents of electricity and found a network of fibers within the cell walls of cable bacteria. They confirmed that these fibers were carrying the current by removing the rest of the cell and zeroing in on the fibers with their electrodes.
This work, reported in Nature Communications, showed that the fibers carry a density of electrical current that is comparable to the wiring in our household appliances. Their conductivity rivals state of the art polymers used in solar panels. “Somehow, biological evolution has invented a structure with extraordinary electrical properties,” said Meysman.
These fibers could one day be used in new materials or to improve the ones we have, as they push behind the limits of our current electric capabilities.