In Western Ghats,a new find: Fungi which can survive 100 degrees C

Studying 25 samples of leaf litter fungi microorganisms that degrade fallen leaves from the Nilgiris,Western Ghats,the researchers have found that spores of nine survived 100 degrees Celsius.

Among these,the spores of Chaetomella raphigera and fungi from the Phoma species survived a two-hour incubation in a drying oven at 110 degrees Celsius,and those of the Bartalinia species survived exposure to 115 degrees Celsius for two hours.

The team was led by T S Suryanarayanan,Director of the Vivekananda Institute of Tropical Mycology (VINSTROM),Ramakrishna Mission Vidyapith,Chennai.

The fungi in this study are among the most heat-resistant

eukaryotes on record, the authors write in a research paper to be published in British journal Fungal

Biology next month.

This was a shock to us. These are mesophilic fungi that are known to survive in moderate temperatures. Even thermophilic fungi,which can withstand extreme heat,havent been reported to survive for this long beyond 100 degrees Celsius, Suryanarayanan told The

Sunday Express. His team had collected the fungi,commonly found on dead leaves,over a year ago to extract enzymes from them.

When we put one in the oven for drying at 100 degrees Celsius,we found the spores survived. We werent expecting to find this. To confirm if this was a more common phenomenon,we subjected several other leaf litter fungi to the thermotolerance test. Since the

results were so striking,we had them verified in other labs, Suryanarayanan said.

The researchers,in collaboration with M Sudhakara Reddy from the Department of Biotechnology,Thapar University,Patiala,have confirmed the molecular identity of the fungi and deposited cultures with the National Fungal Culture Collection of India,Agharkar Research Institute,Pune,and the Institute of Microbial Technology,Chandigarh. They also consulted a fungal spores expert,Nicholas P Money,from the Department of Botany and Western Program,Miami University,Oxford,Ohio,US.

Money,a co-author of the research paper,said in an email interview: The fully-hydrated spores of these fungi can be moved from room temperature to the punishing conditions of dry heat in an oven (115 C),survive baking for up to two hours,and revive almost immediately when they are supplied with moisture. Revival means germinating to produce a normal feeding colony. This is nothing short of astonishing. Fungi exist in two states the vegetative state consists of thin branches called the mycelium,and the reproductive state where seed-like spores are formed. These spores get blown away and if deposited in a suitable place,germinate to produce fungal mycelium. While the mycelium of the heat-resistant fungi identified by Suryanarayanans group,labelled Agnis Fungi in their paper,cannot survive high temperatures,the spores can.

We do not fully understand the mechanism by which these spores survive. Thermophilic microbes usually produce a protective heat shock protein upon encountering high temperatures. But we suspect the fungi under observation have a different mechanism. This is because the shift from room temperature to 100 C and above was immediate, Suryanarayanan said.

The researchers believe the survival mechanism,perhaps evolved from withstanding forest fires,could be either physical or physiological. There are indications that food material is stored in the spores and pigments like melanin could be protecting the surface. These need to be verified. Also,if there are genes involved,they might become important biotechnologically, said Suryanarayanan who is studying the physiological and molecular basis of the temperature tolerance of these fungi.

These fungi,Money said,may serve as models for understanding the underlying molecular mechanisms of heat tolerance that can then be translated to real biotech applications. There are many applications in which fungal tolerance of high temperatures could be valuable. Enzymes extracted from fungi are now used in pharmaceuticals,but these are not stable at high temperatures. Heat tolerance could also come in handy in the case of biocontrol fungi,used to wipe out agricultural pests,but ineffective when exposed to sunlight. The study also raises questions of temperature standards for food processing and safety,said Suryanarayanan.