Imagine plugging a light bulb into a pile of mud and watching it light up. It sounds like something from science fiction, but scientists have recently discovered that certain bacteria can generate electricity! These microscopic organisms are capable of moving electrons outside their cells, creating a flow of electrical current.
The discovery came from scientists trying to understand how bacteria survive in environments that contain little or no oxygen. Most living things rely on oxygen to help release energy from food during metabolism. But many bacteria live in places such as lake sediments, deep soil, or wastewater where oxygen is scarce. Researchers realized that these microbes must have another way to handle the electrons produced during metabolism. Eventually, experiments revealed that some bacteria solve this problem by pushing electrons outside their cells and onto nearby materials like minerals or metal surfaces. This process is known as extracellular electron transfer and it allows bacteria to continue producing energy even without oxygen.
To investigate this strange ability, scientists developed devices called microbial fuel cells. These systems give bacteria a place to grow while also capturing the electrons they release. Inside the fuel cell, bacteria consume organic materials such as waste from plants, animals, or sewage. As the bacteria break down this material, electrons are produced as part of their metabolism. Instead of remaining inside the cell, the electrons are transferred to an electrode and move through a wire to another electrode, producing a measurable electrical current.
Above: A schematic and experimental setup researchers used to study electrical properties of bacteria. Image courtesy of Ganzorig et al.
Some bacteria are especially efficient at generating electricity. One of the most heavily studied examples is Geobacter sulfurreducens. Researchers discovered that this bacterium uses special proteins and tiny hairlike structures called pili to transfer electrons outside the cell. These pili act almost like microscopic electrical wires, allowing the bacteria to connect to nearby surfaces and release electrons. When scientists disrupted these structures in experiments, the bacteria produced far less electricity. Geobacter is not the only bacterium with this ability. Species in the genus Shewanella can also generate electricity, transferring electrons directly to metal surfaces or through molecules that shuttle electrons through their environment.
Researchers even discovered that electricity production is not limited to rare environmental microbes. Some bacteria commonly associated with food fermentation also show electrogenic activity. For example, Lactobacillus plantarum, a bacterium used in fermented foods, has been shown to generate measurable electrical signals during its metabolic processes. The bacterium releases electrons as it processes nutrients, and certain enzymes help move those electrons outside the cell. This finding suggests that the ability to produce electricity might be more widespread among bacteria than scientists originally thought.
One promising application for this research involves wastewater treatment. Wastewater contains large amounts of organic matter that bacteria naturally break down. When electricity producing bacteria carry out this process inside microbial fuel cells, they can clean the water while simultaneously generating electricity. This approach could help wastewater treatment plants reduce their energy use or even produce some of their own power.
Electricity generating bacteria may also contribute to renewable energy systems. Unlike fossil fuels, microbial electricity comes from biological processes that can continue as long as bacteria have access to organic material. Agricultural waste, food scraps, and sewage could potentially serve as fuel sources. Converting these waste materials into electricity could reduce pollution and provide an environmentally friendly source of energy.
Although microbial fuel cells currently produce only small amounts of electricity, the discovery has completely changed how scientists think about bacteria. Instead of seeing microbes only as germs or decomposers, researchers now recognize them as organisms capable of moving electrons and producing electricity. The next breakthrough in clean energy might not come from massive machines, but from the tiny microbes quietly powering the world beneath our feet.
Written by Crystal Zheng, this article was selected as a winner of our 2026 High School Science Communication Challenge. From Lawrenceville, GA, Zheng is a student at Gwinnett School of Mathematics, Science, and Technology.