Climate change is occurring all around us, and research known as attribution science has linked an increasing number of extreme weather events with excessive levels of atmospheric carbon dioxide and other greenhouse gases like methane. As wild weather gets worse worldwide, stress levels will increase not only among humans, but also among other organisms that feel the effects. Stress is also known to increase the levels of reactive oxygen species, which can be detrimental to cellular health. Researchers have now discovered a universal mechanism that underlies the formation of methane gas by many different kinds of cells. Reporting in Nature, a team of researchers has explained why organisms as diverse as microbes, plants, and mushrooms can all release methane at various rates.
First study author Leonard Ernst noted that assumptions have been made about microbes that are enzymatically degrading organic material, and that they were responsible for the release of methane when they existed in oxygen-free environments. "When scientific observations showed that plants, mushrooms, algae, and cyanobacteria also form methane in the presence of oxygen, this was initially attributed to enzymatic activities," Ernst added. But no one could find the enzyme that was catalyzing such a reaction. This study has shown that methane can form without a catalyst, using a chemical process instead.
Reactive oxygen species (ROS) are a normal byproduct of cellular metabolic action, and ROS levels increase when cells are under stress. Organic compounds can be linked to methyl groups with sulfur or nitrogen bonds, and ROS can create methyl radicals by interacting with these compounds. These steps are part of a process that ultimately leads to methane production in a variety of cell types, including bacteria, archaea, yeast, plant cells, and human cells.
The study also revealed that methane formation is directly related to metabolic activity. "The more active the cell, the more methane is formed," noted study co-leader Dr. Ilka Bischofs from the BioQuant Center of Ruperto Carola.
The research could be crucial to climate change, as researchers have long been seeking to understand how methane was generated and released, and why the levels are increasing so much.
"Our findings could prove to be a milestone for understanding aerobic methane formation in the environment, since this universal mechanism can also explain our earlier observations on the release of methane from plants," said study co-leader Professor Frank Keppler from Heidelberg University’s Institute of Earth Sciences.
Additional work showed that oxidative stress, which can be caused by higher temperatures in the environment or excessive ROS levels, also led to an increase in methane formation in a variety of cell types. When antioxidants, which can counteract the impact of ROS, were applied to cells, methane production decreased.
"This interaction with physical and chemical stress factors would also explain why an individual organism can release very different quantities of methane," said Keppler. Methane levels in the breath might be used to measure oxidative stress levels or monitor immune reactions, added Keppler.