Greenhouse gas: All life produces methane

After carbon dioxide, it is the greenhouse gas with the second largest contribution to current global warming: It is not without reason that methane has been the focus of scientific research for some time.

Until now, experts have assumed that special microorganisms are responsible for the production of the gas.

Researchers at Heidelberg University have now been able to show that methane is also produced by a purely chemical mechanism that can take place in any type of organism.

"This study is a milestone in our understanding of aerobic methane formation in the environment," geoscientist Frank Keppler is quoted as saying in a statement from the Max Planck Society.

"The universal mechanism also explains the earlier observations on the release of methane from plants."

The fact that methane is not only formed by microorganisms in cow stomachs or rice fields has become increasingly evident over the past fifteen years.

The formation of the greenhouse gas could be detected successively in fungi, algae and cyanobacteria.

Only the process behind it remained unclear: the assumption that it had to do with an enzymatic reaction has only now been refuted.

The ones in "Nature"

Published results suggest that methane is formed under oxygen conditions whenever cells have sufficient iron, methylated sulfur or nitrogen compounds, and oxidizing molecules.

Special enzymes or catalysts are not necessary.

According to the study, the mechanism opens up “a completely new perspective on the formation and biochemical cycle of methane”.

The researchers first demonstrated the mechanism using the bacterium

.

Subsequently, the oxygen-based formation of methane could be observed in more than thirty model organisms, including bacteria, archaea, yeast fungi, plant cells and human cell lines.

Methane, the scientists write, may be a "universal by-product of life," a "conserved property of all living systems."

Particularly significant: The experiments confirm that methane formation is directly dependent on the metabolic activity and thus the stress level of an organism.

The reaction is significantly enhanced by biomolecules such as ATP and NADH, which are associated with increased metabolic activity.

It is therefore conceivable that stress caused by rapid global warming leads to higher methane emissions from organisms.

Exact figures are not yet available, says first author Keppler when asked.

For this purpose, an "enormous experimental and analytical effort" will be necessary in the future.

The study opens up a second new possibility: Fluctuations in the methane content of the air we breathe could be used in the future to draw conclusions about age-related or stress-related metabolic changes.