Bacteria breathe electricity unlocking bioenergy and clean tech potential

The team identified how these bacteria use a natural process called extracellular respiration to expel electrons. The discovery, combining biology with electrochemistry, reveals how bacteria survive and generate energy without oxygen, offering a new lens on microbial life and its technological potential.

"Our research not only solves a long-standing scientific mystery, but it also points to a new and potentially widespread survival strategy in nature," said Ajo-Franklin, director of the Rice Synthetic Biology Institute and CPRIT Scholar.

While oxygen typically serves as the final electron acceptor in energy metabolism for modern organisms, some bacteria evolved alternative mechanisms in low-oxygen environments such as deep-sea vents and the human gut. The Rice-led team found that bacteria employ naphthoquinones-naturally occurring molecules-to transfer electrons to external surfaces, operating like a battery discharge.

Scientists had previously used this phenomenon in biotech but lacked a clear understanding of its mechanism. This study provides critical insight, indicating that external electron transfer may be common across microbial species.

"This newly discovered mechanism of respiration is a simple and ingenious way to get the job done," noted Biki Bapi Kundu, Rice doctoral student and first author. "Naphthoquinones act like molecular couriers, carrying electrons out of the cell so the bacteria can break down food and generate energy."

In collaboration with Bernhard Palsson's lab at the University of California San Diego, researchers simulated bacterial growth in oxygen-free settings rich in conductive surfaces. The models, validated through lab experiments, confirmed that bacteria could thrive and generate electricity by discharging electrons into these materials.

This interdisciplinary study enhances understanding of bacterial metabolism and introduces a method for electronically monitoring and potentially controlling microbial behavior in real time.

The implications are wide-ranging. Processes like wastewater treatment and biomanufacturing could benefit from bacteria that resolve electron imbalances, improving efficiency. The discovery may also aid in capturing CO2 through renewable electricity, mimicking photosynthesis but using bacteria.

"It opens the door to building smarter, more sustainable technologies with biology at the core," Ajo-Franklin added.

Potential applications extend to bioelectronic sensors for use in low-oxygen settings such as medical diagnostics, environmental monitoring, and space missions.

The study was co-authored by Jayanth Krishnan, Richard Szubin, Arjun Patel, Bernhard Palsson, and Daniel Zielinski of UC San Diego and supported by CPRIT and the Novo Nordisk Foundation.

Research Report:Extracellular respiration is a latent energy metabolism in Escherichia coli