Picky methane-consuming microorganisms prefer carbon monoxide, opening the door to more greenhouse gas release

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Research by microbiologists Reinier Egas and Cornelia Welte of Radboud University shows that many methane-consuming microorganisms actually prefer carbon monoxide over methane. When carbon monoxide is present, they consume far less methane. This suggests that in carbon monoxide–rich environments, more methane may be released from the soil into the atmosphere. The paper is published in the journal Nature Communications.

Soils contain methanotrophs—microorganisms that consume methane. This is beneficial, as it prevents the harmful greenhouse gas from escaping into the air. Egas researched what happens when these microorganisms are exposed to substances other than methane. "It turned out that certain methanotrophs strongly prefer carbon monoxide. In carbon monoxide–rich environments, they are therefore likely to consume much less methane."

Pandas and bamboo

This preference is understandable, as carbon monoxide yields much more energy than methane. The microorganisms were also significantly more active when consuming carbon monoxide. Egas explains, "We observed in their DNA that these microorganisms are actually better adapted to using carbon monoxide than methane. There wasn't just one gene involved in carbon monoxide consumption, but eight—an exceptionally high number. Methane consumers are a bit like pandas eating bamboo: they need to consume large amounts to obtain very little energy. It's highly inefficient."

As a result, these so-called methane consumers may be misnamed—they behave more like carbon monoxide consumers. In areas where both gases are abundant in the soil, these microorganisms may no longer function effectively as a methane filter, allowing more methane to escape into the atmosphere. "We still know very little about where carbon monoxide occurs in high concentrations and how this influences methane emissions. We know it is present in the soil, but how much and where exactly still needs further investigation," the microbiologist explains.

Ecological research needed

The methane filter is therefore less robust than previously assumed. "Carbon monoxide can significantly disrupt the methane filter. If this filter no longer functions properly, even more methane will enter the atmosphere—this at a time when methane emissions are already a major concern. We must prevent that," says Egas.

The key is to map where carbon monoxide is present, understand how it is formed, and determine whether its concentrations are high enough to disrupt the soil's methane filter. "We want to explore how we can support the methane filter to ensure it continues to function effectively."

Publication details

Reinier A. Egas et al, Carbon monoxide metabolism in freshwater anaerobic methanotrophic archaea, Nature Communications (2026). DOI: 10.1038/s41467-026-70080-4

Journal information: Nature Communications

Key concepts

carbon fluxgreenhouse gases

Provided by Radboud University