Consider them the microscopic cable guys. In muddy sediments all over the world, tiny bacteria eat and grow by building electrically conducting wires into the muck. Now, researchers say they have discovered how these miniature electricians, known as cable bacteria, do it: by crafting tiny plates out of nickel and organic compounds and bundling and braiding them into conductive fibers.
The researchers believe they have found the first biological example of a metal-organic framework, a material whose makers were honored in October 2025 with the Nobel Prize in Chemistry. The bacterial conduits also conduct electricity much better than synthetic organic wires, which could offer a template for growing flexible, biocompatible electronics with low metal and energy inputs.
The study, posted in October 2025 as a preprint on bioRxiv, has yet to be peer reviewed. However, Lars Peter Nielsen, an Electromicrobiologist at Aarhus University who was not involved in the study, says the result is “very impressive.” “If it holds true, this is a major step in our understanding of what cable bacteria can accomplish,” he says. “This is what we’ve been chasing for years.”
Since Nielsen’s team first discovered cable bacteria in 2009 in Denmark’s Aarhus Harbor, the microbes have been found worldwide in sediments in lakes, rivers, and oceans. They feed on sulfur-rich compounds that are released by decaying organic matter, such as hydrogen sulfide. Bacteria swipe electrons from the smelly, colorless gas and ultimately pass them to oxygen that is abundant only in the top layer of the sediment. As the electrons go from a higher energy state in hydrogen sulfide to a lower one in oxygen, the microbes can harvest some of this energy difference for themselves.
To grow and access the hydrogen sulfide that’s abundant in deeper sediments, the microbes must continue to complete the reactions by passing electrons to oxygen at the surface. The bacteria’s solution: Divide and cooperate. As the bacteria multiply, extending the wires into the mud, they form an individual superorganism that shares a single outer cell membrane. “It’s a unique phenomenon in biology,” says Derek Lovley, a Microbiologist at the University of Massachusetts Amherst.
To date researchers have found wires up to 5 centimeters long that consist of up to 25,000 cable bacteria working in cooperation to construct what amounts to a snorkel. A single square meter of sediment can contain an estimated 20,000 kilometers of bacterial wires. Researchers are finding that these little engineers restructure the chemical landscape of sediments, by promoting mineral transformations, driving nutrient cycling, and stimulating ion migration that acidifies deeper layers.
More than a decade of study, however, had failed to determine the structure of the wires. This is now coming into focus with research led by Filip Meysman, a Chemical Engineer at the University of Antwerp. He and his colleagues isolated individual filaments of the bacteria, and, using electron microscopy, found that arrayed around their perimeter were dozens of ridges, each containing conductive fibers just 50 nanometers across. Zooming in closer, they saw that these fibers contained even smaller bundles of braided “nanoribbons.”
Next, the team used chemical clues from x-ray spectroscopy, x-ray fluorescence, and computer modeling to deduce the structure of these nanoribbons. The researchers now believe the cable bacteria harvest trace amounts of nickel from the sediments and water and create long, platelike structures by linking those metal atoms to sulfur-rich organic compounds. These plates are then stacked to create the nanoribbons, which are in turn braided into bundles, creating flexible wires like the braided copper wiring used in home electronics today. “It’s impressive how evolution has optimized this structure,” Nielsen says.
Moreover, the researchers believe this structure represents the first biologically produced metal-organic framework, a class of material that has fascinated chemists for years. The voids within these porous materials can be tailored to trap specific molecules, making them useful for storing gases such as hydrogen and methane, or soaking up water vapor or carbon dioxide out of the air.
Chemists have also come up with their own ways to synthesize nickel and organic compounds into conductive nanowires. However, Meysman and his colleagues report that the bacterial nanoribbons are 100 times more conductive than modern synthetic versions. According to Lovley, researchers are already working to adapt other bacterial conductors to create artificial neurons and new types of chemical sensors — and even harvest electricity directly from humid air. Lovley says: “Maybe cable bacteria will lead to something else.”
REFERENCE: Science; 07 NOV 2025; Robert F. Service