IIT Madras: role of mushroom spores in atmospheric bioaerosols studied

Terrestrially occurring mushrooms are a source of biological aerosols that occupy the atmosphere.

Researchers from the Indian Institute of Technology (IIT) Madras have for the first time, over the Indian region, attempted to demonstrate the potential role of mushroom spores in atmospheric bioaerosols. While others have studied the diversity and distribution of mushroom and the presence of mushroom spores in the atmospheric aerosol separately, the IIT team has proved the role of terrestrially occurring mushrooms as a source of biological aerosol particles in the atmosphere. The results were published recently in the journal PLOS ONE.

The study was undertaken on IIT Madras campus, which is spread over 678 acres and has very rich vegetation. It is considered an ‘ecological island’ representative of tropical dry evergreen biome.

DNA analysis

Biodiversity of fungal species in the study site was studied using DNA analysis. To identify the type and diversity of atmospheric fungal spores, DNA analysis of particulate matter was carried out subsequently. The DNA analysis of 165 mushrooms revealed that there are 113 different species of mushrooms belonging to 54 genera and 23 families.

“Source characterisation of airborne fungal spores has been done for the first time in India — we studied the mushrooms and spores released by the mushrooms and present in air,” says Prof. Sachin S. Gunthe from the Department of Civil Engineering, IIT Madras, and the corresponding author of the paper.

“Mushrooms grow during monsoon and when the temperature and relative humidity are favourable, spores are released into the air,” says Prof. R.S. Verma from the Department of Biotechnology, IIT Madras, and one of the authors of the paper.

“There was 17% match between mushroom species found on land and spores in the air,” says Hema Priyamvada, a doctoral student from the Department of Civil Engineering, IIT Madras, and the first author of the paper. Spores collected from the mushroom and from the air were studied to understand how the spores look morphologically — size, shape and surface features.

SEM images

“Morphological characterisation of fungal spores will be useful for identification of spores in the atmosphere. Since fungal spores account for huge fraction of bioaerosols, the SEM images will be helpful in quick and efficient identification,” says Priyamvada.

The researchers have also quantitatively estimated the contribution of mushroom spores to atmospheric aerosol by modelling the dispersion of spores from the mushroom. “We found that of the certain number of spores (540 spores per sq. cm) released per second from a mushroom, 6% reached a distance of 100 metres for one second of release. In ambient conditions, the release can happen for a longer time — up to an hour — so the contribution of spores to the atmospheric aerosols will be huge,” she says. “Once released from mushrooms, spores can remain suspended in air for a long time and travel great distances.”

“We tried to show mushrooms growing in similar kind of ecosystem as IIT Madras are releasing spores into air. It means, to an extent, you can extrapolate these findings to other tropical dry evergreen biomes in India,” says Prof. Gunthe.

Besides causing allergy in humans, spores can also damage plants and animal health. It can also have an impact on regional climate. By acting as ice nuclei, the fungal spores can accelerate vapour condensing around spores and forming water droplets. “Presence of specific types of bioaerosol can even advance the precipitation processes especially in convective clouds,” says Prof. Gunthe.