The electricity-conducting cable bacteria Electronema is “Microbe of the Year 2024”. Tens of thousands of tiny microorganisms can form chains up to five centimeters long, also called cables. “These are connected by current-conducting protein fibers in their cell shell,” said the Association for General and Applied Microbiology (VAAM) in Frankfurt.
The chain shape of the bacteria of the genus Electronema enables a special division of labor. Thousands of cells of each individual cable live in the lower part of the sediment of water bodies, where they convert sulfide to sulfate. This creates negatively charged electrons that flow via the current-conducting fibers to the other end of the cable on the sediment surface and are transferred there to oxygen.
Only discovered twelve years ago
This makes cable bacteria the only organisms that can consume the sulfide in a zone where there is no oxygen. This is “a major advantage over competing microorganisms,” according to the VAAM. Cable bacteria were only discovered at the bottom of seas and lakes twelve years ago.
Although cable bacteria can be detected in nature, they have not yet been able to be propagated in isolation in the laboratory. Among other things, they can also promote the breakdown of pollutants in water and reduce the formation of greenhouse gases. "A large amount of climate-damaging methane is produced every year in flooded rice fields. Cable bacteria live in the root area of rice plants and can reduce methane formation there."
The electrical conduction in the protein fibers of the cable bacteria is similar to that of a metallic cable, writes the VAAM. This makes them extremely interesting for electronics based on biomaterials. The conductive structures of the cable bacteria have already been patented, but the development is still a long way from commercial implementation.