15 February 2022

Carbon keepers fungi are the soil secret weapon against climate change


Soils with higher amounts of fungi release less CO2, University of Zurich finds. A major discovery for the study of new solutions in the fight against climate change

by Matteo Cavallito


Fungi can be a key factor in soil carbon sequestration according to a recent research published in ISME Communications, the official journal of the International Society for Microbial Ecology. The investigation, carried out by a team of scientists led by Luiz A. Domeignoz-Horta, a microbiologist at the University of Massachusetts and the Department of Evolutionary Biology at the University of Zurich, provides key new information for understanding a crucial process that impacts soil health and climate change. While also showing the potential of these microorganisms in their interaction with organic matter.

Soil, microbes and carbon: a tricky relationship

Carbon sequestration is one of the most important soil functions. But captured by soil organic carbon appears in different forms. In some cases, the element can be processed and stored for a long time, even up to a century. In other contexts, it can be rapidly released. These dynamics are still not quite clear, so it is not surprising that many scientists are trying to uncover the role of a number of factors in shaping this ongoing cycle affecting the ecosystem.

“As the climate changes, the rate at which the Earth’s climate warms depends in part on the persistence of soil organic carbon,” the researchers say. “Here we tested the hypotheses that distinct microbial communities shape the composition of soil organic matter, and microbial-derived soil organic matter has distinct decomposition potential depending on its community of origin.”

The experiment

During their investigation, Domeignoz-Horta and his colleagues at the University of Zurich observed several soil samples in the laboratory. Evaluating their reactions to the activities of five different combinations of fungi and bacteria. “We inoculated microbial communities of varying diversities into a model soil matrix amended with simple carbon (cellobiose, ed: a disaccharide that can be can be hydrolyzed by microorganisms) and measured the thermal stability of the resultant soil organic matter (SOM),” the researchers explain.

“While diversity was not a driver of SOM composition”, they say, “bacteria-only communities lead to more thermally labile soil C pools than communities with bacteria and fungi. Our results provide direct evidence for a link between microbial community structure, SOM composition, and thermal stability. This evidence demonstrates the relevance of soil microorganisms in building persistent SOM stocks”.

Fungi are crucial

In brief: after a period of four months in which the microorganisms had been able to develop, the scientists heated the different soil samples and measured their emissions. Soils with more fungi released less CO2 and therefore retained more carbon.

The reason behind this is still unknown. But scientists have suggested that fungi are able to produce enzymes that can build more stable organic building blocks. Anyway, the study offers an important contribution to the search for new solutions designed to promote carbon storage in the soil. Thus helping to mitigate climate change trough a better soil management.