Hypothermia is a characteristic of the fungal kingdom

Fungi play essential roles in global ecology and economy, but their thermal biology is widely unknown. Infrared imaging revealed that mushrooms, yeasts, and molds each maintained colder temperatures than their surroundings. Fungal specimens are to be ~2.5 °C colder than the surrounding temperature. Time-lapse infrared images of Pleurotus ostreatus revealed hypothermia throughout mushroom growth and after detachment from mycelium. The hymenium was coldest, and different areas of the mushroom exhibit distinct thermal changes during heating and cooling. The fruiting area in the mycelium remained relatively cold following mushroom detachment. Analyses of Agaricus bisporus mushroom pilei confirmed that the mechanism for mushroom hypothermia depends on evaporative cooling. We also assessed evaporative cooling in biofilms of Cryptococcus neoformans, and Penicillium spp. molds based on the accumulation of condensed water droplets on the lids over biofilms grown on agar media plates. Biofilms of C. neoformans acapsular mutant showed more transpiration and were colder than wildtype. Penicillium biofilms appear to transpire ten times more than the supporting agar. We used the evaporative cooling capacity of mushrooms to construct a mushroom-based air-cooling system (MycoCooler™) capable of passively reducing the temperature of a closed compartment by approximately 10 °C in 25 minutes. This study suggests that hypothermia is a characteristic of the fungal kingdom. Since fungi make up ~2% of Earth biomass, their ability to dissipate heat may contribute significantly to planetary temperatures in local environments. These findings are relevant to the current global warming crisis and suggest that large-scale myco-cultures could help mitigate increasing planetary temperature.