Indians discover world's most heat-resistant fungi

Spores are reproductive cells capable of developing into a new individual without fusion with another reproductive cell. The team of fungi researchers found the heat-resistant spores in dead leaves.

"It took us around one and a half years to arrive at our conclusion. It is a preliminary but significant finding. It is reported for the first time that fungi spores can survive even 115 degrees Celsius," T.S. Surayanarayanan, director of the Vivekananda Institute of Tropical Mycology (VINSTROM), told IANS in an interview.

The fungi are among the most heat-resistant eukaryotes (organisms with a membrane-bound nucleus) on record, he said. They have been named 'Agni's Fungi' after the Hindu god of fire.

VINSTROM is part of the Ramakrishna Mission Vidyapith that runs the famed Vivekananda College and other institutes here.

The fungi were particularly found in leaf litter isolated from tropical semi-arid habitat in the Western Ghats in southern India.

The spores may have adapted to the environment as the region is known to have forest fires, Suryanarayanan said.

Along with bacteria, they degrade dead leaves by breaking down their molecular structure as opposed to other fungi that damage living trees and plants.
Among the 25 species of fungi isolated from leaf litter, spores of nine of them were able to germinate after incubation in drying oven for over two hours at 100 degrees Celsius.

The spores of Chaetomella raphigera and Phoma survived two hours' incubation at 110 degrees Celsius and the spores of Bartalinia - the more heat-resistant - survived an exposure of two hours at 115 degrees Celsius.

Longer exposure of Bartalina spores to lower temperatures was as lethal as shorter exposures to temperatures higher than 115 degrees Celsius.

The heat resistance of fungal spores is a function of both time and temperature, Suryanarayanan said.

The research paper was authored by Surayanarayanan along with M.B. Govindarajalu, E. Thirumalai (VINSTROM), M. Sudhakara Reddy (Thapar University, Patiala) and Nicholas P. Money (Miami University, Oxford Ohio, US).

"There are heat-loving fungi. Hitherto the reports were that fungi are thermo tolerant up to 60 to 70 degrees Celsius. But these fungi spores tolerate high levels of heat not seen previously," Suryanarayanan told IANS.

rchers conducted repeated tests to be sure of their results as it was the first time they come across  fungi that survive  after being exposed to very high temperature.
Their paper will be published in British Journal Fungal Biology.

According to Suryanarayanan, there are around 1.5 million species of fungi, only seven percent of which are known all over the world.

"The discovery can have an application in the area of pesticides as there are fungal pesticides that are good at lab level but ineffective on the fields due to the temperature outside," he added.

"Please note that spores do not grow. To make the spores grow the temperature has to be reduced to a lower temperature such as 30 degrees Celsius," said S. Shivaji, a director grade scientist at the Centre for Cellular and Molecular Biology in Hyderabad.

"If the spores could be grown at more than 100 degrees Celsius it would have been very significant since under these high temperature conditions, the fungi could produce biomolecules such as enzymes of biotechnological use and importance," Shivaji told IANS.

Agreeing, Surayanarayanan said the discovery of such heat-resistant fungi has implications for the temperature standards followed in the food processing industry.
The fungi cultures have been deposited with the National Fungal Culture Collection of India, Agharkar Research Institute, Pune, and the Institute of Microbial Technology, Chandigarh.