Microorganisms invisible to the eye in the depths of the sea have been shown to consume the greenhouse gas methane (CH₄). Methane, one of the main culprits of global warming, is emitted in smaller quantities than carbon dioxide, but has a warming effect dozens of times more powerful. These microorganisms act as a 'living filter,' preventing methane that escapes from deep-sea sediments from rising into the atmosphere.
Researchers from the University of Southern California (USC), California Institute of Technology (Caltech), Peking University in China, and the Max Planck Institute for Marine Microbiology in Germany noted on the 23rd in the international journal 'Science Advances' that they have confirmed the fact that completely different types of microorganisms, archaea and sulfate-reducing bacteria, work together to consume methane in the deep sea.
Archaea are microorganisms that live in extreme environments such as hot acidic springs, hydrothermal vents in deep seas, and salt lakes. Despite the name, they are distinct from bacteria. The core of this study is anaerobic methane-oxidizing archaea and sulfate-reducing bacteria.
Anaerobic methane-oxidizing archaea can break down methane, but if they cannot process the electrons produced in the process, the reaction stops. Sulfate-reducing bacteria cannot break down methane, but instead, they take in the electrons released by the archaea and react them with sulfate to continue their metabolism.
Although these microorganisms belong to completely different taxonomies, when they join forces, everything works well. Archaea generate electrons by splitting methane, and sulfate-reducing bacteria use these electrons as energy. The two microorganisms essentially exchange electrons to survive.
Moh El-Naggar, a professor at USC, explained, "The two microorganisms physically cluster together and connect like an electrical circuit," adding, "Proteins that act as conductors connect them, allowing the flow of electrons."
The researchers collected samples from various underwater methane emission sites, including the Mediterranean and the California coast, and directly measured electron transfer. As a result, these microorganisms were actually forming an electrical consolidation that significantly reduced methane emissions.
Hang Yu, a professor at Peking University, stated, "These microorganisms act as natural guardians that protect the Earth," and added, "We can gain insights into how life forms have evolved over billions of years to consume greenhouse gases, even in extreme environments."
This discovery is not just limited to understanding microbial ecology. By utilizing this principle, new technologies can be developed to reduce methane emissions in landfills or factories.
Victoria Orphan, a professor at Caltech, remarked, "It's remarkable that even the most remote microorganisms cooperate in such sophisticated ways to impact the entire planet," and added, "This serves as evidence of just how much more there is to learn about the microbial ecosystems we rely on."
References
Science Advances (2025), DOI: https://doi.org/10.1126/sciadv.adw4289