New research reveals that mushrooms and other fungi can stay cooler than their surroundings. The discovery could tell us more about the evolution of these organisms and how they might respond to ongoing global warming.
Like some of the best scientific discoveries, this temperature regulation was accidentally discovered, when one of the researchers was testing a thermal camera during the pandemic – and noticed that the mushrooms growing in the nearby woods were cooler than the surrounding vegetation.
The researcher then recruited a team of molecular biologists from Johns Hopkins University in Maryland and a colleague from the University of Puerto Rico to take a closer look at what was going on.
“In contrast to animals and plants, temperature and thermoregulation of fungi are relatively unknown,” the researchers write in their published paper. “Our data suggest that not only mushrooms, but also mold and fungal communities can maintain cooler temperatures than their surroundings.”
Although mushroom cooling has been reported and observed, it has not been closely studied. Here, the team analyzed mushrooms in the wild and other fungal species in the lab to look for temperature differences.
On average, the mushrooms turned out to be 2.9 °C (5.2 °F) cooler than the surrounding air, with a margin of uncertainty of 1.4 °C (2.5 °F). With some mushroom species, the mushroom temperature was up to 5.9 °C (10.6 °F) lower.
Through laboratory experiments where water content and temperature can be manipulated, the researchers confirmed that mushrooms regulate their temperature through evapotranspiration, or releasing water into the air. Substantial amounts of water can be held under the mushroom caps before being released slowly and evenly.
Also, other types of fungi can pull off the same trick, with colonies tending to be cooler closer to the center. This seems to happen regardless of the outside temperature, even if it’s close to freezing.
“We show that mold and fungal colonies are also cooler than the environment and use the process of evapotranspiration to release heat,” the researchers wrote. “Relative cold seems to be a general characteristic observed throughout the fungal kingdom.”
As fungi make up about 2% of Earth’s biomass, their cooling properties can help regulate local environments. The researchers tested this by creating a basic mushroom-powered cooler as part of their study. They used Agaricus Bisporus to effectively lower the temperature within a sealed enclosure – further evidence of the mushrooms’ cooling ability.
Such thermoregulation is important not only for understanding more about fungi, but also for modeling climate change. These organisms play a vital role in Earth’s ecological cycles, and we need to know how they will adapt in the future and how they can help other plants and animals adapt as well.
What the team hasn’t addressed here is exactly why fungi like to cool off. Past research suggests that the loss of water vapor allows mushrooms to create local airflow to help disperse their spores, but many questions remain.
“The extent to which fungal temperatures vary according to their environmental niche likely involves several factors that require further study,” the researchers write.
“The temperature of wild mushrooms, as well as fungal and fungal colonies, relative to the environment varies by genus, suggesting that there may be species-specific differences in their abilities to dissipate heat.”
The research was published in PNAS.