Madrid, 10 (European press)
Scientists from the University of Heidelberg and the Max Planck Institute for Microbiology have revealed that the formation of the greenhouse gas methane depends on a global mechanism.
The multidisciplinary research team discovered that methane originates in the cells of living organisms by a purely chemical process. Studies, among other things, provide an explanation for why methane is released not only by the activity of special microorganisms, but also, as observed for some time, also by plants and fungi. The findings are an important step toward understanding the formation of aerobic methane in the environment, according to the authors.
Methane contributes to global climate change as a greenhouse gas. That is why the natural and anthropological reasons for its appearance are of special scientific interest. “For a long time it was assumed that methane consists only of so-called archaea or archaea when they break down organic matter in the absence of oxygen. When scientific observations showed that plants, fungi, algae and cyanobacteria also form methane in the presence of oxygen, this was initially attributed to the activities Enzymes,” explains Leonard Ernst, first author of the study, which was published in the journal Nature.
However, no enzyme responsible for doing this has yet been found in any of these organisms. Scientists have now been able to prove that methane can also form without such a catalyst, with the help of a purely chemical mechanism.
This mechanism is driven by reactive oxygen species (ROS) that arise through the metabolic activity of cells. In interaction with the basic element iron, these oxygen compounds, in all living organisms, participate in a chemical reaction that, through several steps, leads to the formation of highly reactive metabolites. These substances prefer to separate the methyl radical from sulfur and nitrogen compounds. Methane is formed through a subsequent reaction with hydrogen atoms.
With the help of the bacteria Bacillus subtilis, the researchers were able to show that the degree of methane formation is directly related to metabolic activity: “The higher the cell activity, the more methane is formed,” explains Ilka Bischofs, the group leader. A research project of the BioQuant Center of the University of Heidelberg and the Max Planck Institute for Terrestrial Microbiology.
The study was able to demonstrate ROS-associated methanogenesis in more than 30 model organisms, from bacteria and archaea to yeast, plant cells and human cell lines. Accordingly, according to Leonard Ernst, it is very likely that this purely chemical formation of methane occurs in all living things. “Our findings could be a milestone in understanding aerobic methane formation in the environment, as this global mechanism may also explain our previous observations of methane release from plants,” says Professor Kepler.
In addition to increased metabolic activity, oxidative stress, caused by higher environmental temperatures or addition of ROS-forming substances, also increased methanogenesis in the studied organisms. When scientists confronted it with the help of antioxidants, methane formation decreased, an interaction of factors that can regulate the appearance of methane in living organisms.
“This interaction with physical and chemical stressors would also explain why an organism is able to release very different amounts of methane,” says fellow team leader Dr. Frank Kepler. “Thus, fluctuations in methane in a person’s breath can give indications of the level of oxidative stress or indicate immune reactions,” he added. In addition, the effects of climate change on environmental conditions and temperature are also supposed to affect the stress level of many organisms and cause them to release more methane.
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