Air full of fungi, study reveals

Researchers from Mainz find great diversity of fungi floating in the air


The amount and diversity of fungi floating in the air are both much higher than previously thought, according to new German research published in the Proceedings of the National Academy of Sciences (PNAS). According to the study, we breathe in between 1 and 10 fungal spores every time we inhale. The findings are important because many fungi trigger allergies, cause diseases in people and animals, and damage plants. Fungal spores also play a role in cloud formation.

Scientists have known for some time that fungi make up a significant proportion of the tiny particles floating in the air in both urban areas and natural environments such as rainforests. However, until now the diversity of these airborne fungi has not been documented. In this latest study, the scientists collected samples of both fine and coarse particulate matter floating in the air over a period of a year. They then used DNA analysis to identify the fungal species present in the samples.

"In order to fish the different species out of the genetic soup of our samples, we used a kind of genetic fishhook," explained Janine Fröhlich of the Max Planck Institute for Chemistry and the Johannes Gutenberg University in Mainz, Germany. "However, in contrast to earlier studies, we used several different baits for different fungal species. In this way, we were able to identify a significantly larger proportion of the species present. In addition, we collected and analyzed samples for a year, which gave us much more extensive and more meaningful data than previous studies."

The researchers were able to identify several hundred fungi species in their samples. On average, there are between 1,000 and 10,000 fungal spores in every cubic meter of air.

"A person breathes in between 10,000 and 20,000 liters of air every day, and every breath contains between 1 and 10 spores," commented Viviane Després of Johannes Gutenberg University Mainz. "Our data show that the diversity of airborne fungi [...] is much higher than indicated by earlier studies," the scientists conclude. "Information about the diversity and abundance of airborne fungi and other bioaerosol particles is relevant for many areas of research such as biogeosciences, climate and ecology, human and veterinary medicine, industrial and environmental hygiene, agriculture, bioengineering, and security."

"We are interested in the number of fungal spores in the air for three reasons," explained Ulrich Pöschl of the Max Planck Institute for Chemistry, who led the study. "Firstly, we can use the spores to investigate whether ecosystems are being altered by climate change. Secondly, fungal spores play an important role as an allergy trigger, a cause of plant damage, and a disease trigger in people, plants, and animals." In addition to this, fungal spores could help to set off rainfall, he adds. "Fungal spores and other biological aerosol particles can serve as condensation and crystallization nuclei for water drops and ice crystals, and so contribute to the creation of clouds, fog, and precipitation," he noted.

Further studies of the number and properties of the fungal spores in the air could help to improve our understanding of these processes in the climate system. "The interactions are so complex that we are always finding new process and factors that we have to take into account," said Dr. Pöschl of the link between fungi, the biosphere, and the climate.