E. coli can breath electricity

Most of us first meet Escherichia coli (E. coli) in a high school biology class, usually as a friendly lab organism, or in less happy circumstances, as the culprit behind food poisoning. But what if I told you this unassuming microbe has a secret superpower: it can literally breathe electricity?

That’s the surprising discovery reported in Cell by a team of researchers from Rice University, the University of California San Diego, and the Technical University of Denmark. The paper, titled “Extracellular respiration is a latent energy metabolism in Escherichia coli”, reveals that E. coli, long thought to rely only on fermentation when oxygen is scarce, can actually survive and grow by sending its metabolic waste, electrons, straight into a wire.

This discovery could reshape how we think about microbial life, renewable energy, and even our own gut microbiome.

Every living thing has to find a way to dispose of electrons, the byproducts of breaking down food for energy. For us, oxygen does the job nicely: when we breathe, oxygen molecules accept those electrons, letting our cells keep running.

Microbes, however, are more creative. Some bacteria can “breathe” not just oxygen but also nitrate, sulfate, or even iron minerals in the soil. A few unusual species, like Shewanella and Geobacter, go a step further: they can push their electrons onto solid surfaces outside the cell, a process called extracellular electron transfer (EET). In nature, this lets them survive in oxygen-free mud by using rocks or metals as their “lungs.” In the lab, it means they can power tiny microbial batteries.

E. coli, by contrast, has always been classified as a non-electric bacterium. Under oxygen-free conditions, it was assumed to rely on fermentation, an inefficient process that leaves it sluggish compared to its electro-active cousins. But the new study shows that the assumption was wrong.

The research team focused on a chemical called 2-hydroxy-1,4-naphthoquinone (HNQ). This molecule, also known as “lawsone” (it’s the pigment that gives henna its dyeing power), can act like a shuttle, carrying electrons from inside the cell to an external surface.

The scientists found that when E. coli was given HNQ and connected to an electrode, the bacteria started behaving like natural “electric breathers.” Using a mix of genetic editing and electrochemical monitoring, they traced the process to two enzymes inside the cell, nitroreductases NfsA and NfsB. These enzymes, normally thought of as general detoxifiers, turned out to be excellent at reducing HNQ. In simple terms, they could hand off electrons to the shuttle, which then delivered them to the outside world.

Even more surprising, E. coli quickly adapted to make the process more efficient. After a short evolutionary trial, the bacteria repeatedly developed the same tiny mutation in a membrane protein called OmpC, which improved their ability to interact with the electrode. With that tweak, the microbes were actually growing using the electrode as their only source of electron disposal.

In other words, E. coli had unlocked a whole new way to live.

The discovery shows that E. coli has a “latent” energy metabolism that had gone unnoticed. It doesn’t need oxygen, nitrate, or fermentation, it can grow using electricity itself as the sink for electrons. This suggests other bacteria may also be hiding untapped energy pathways, waiting to be uncovered. Microbes that can plug into electrodes have long been studied for microbial fuel cells (tiny biological batteries) and waste-to-energy systems. But most naturally electric bacteria are slow-growing and tricky to engineer. E. coli, by contrast, is the lab rat of biotechnology: easy to manipulate, fast-growing, and already central to industries from insulin production to biofuels. If we can harness its electrical mode, we might build more efficient bioreactors, bioelectronic sensors, or even living circuits. The human gut is low in oxygen, forcing microbes there to get creative with their energy. The study hints that E. coli and its relatives might use molecules like HNQ in the gut environment, transferring electrons to other compounds or even to neighboring microbes. Understanding this could reshape our view of the microbiome’s role in health. And on a bigger scale, it raises questions about microbial survival strategies in soil, sediments, or even extraterrestrial environments.

The authors end their paper with a provocative idea: perhaps we should think of metabolism not just as a flow of carbon, but as a flow of electrons. Just as rivers carve landscapes, electron streams shape the possibilities for life. By uncovering how E. coli taps into external electron highways, the study adds a new piece to that picture.

It also gives scientists a roadmap for exploring similar processes in other microbes, and even for designing synthetic organisms that can seamlessly connect with electronics. Imagine probiotic pills that power medical sensors, or wastewater treatment plants where bacteria both clean and generate electricity.

It’s delightful that the key to this discovery was a humble pigment from henna, a plant dye used for centuries in body art. Who would have guessed that the same molecule responsible for swirling wedding patterns on hands could also reveal a hidden electric life in bacteria?

If you want to learn more, read the original article titled "Extracellular respiration is a latent energy metabolism in Escherichia coli" on Cell at http://dx.doi.org/10.1016/j.cell.2025.03.016.