Thermophilic fungi can represent a rich source of industrially relevant enzymes.
Here, 105 fungal strains capable of growing at 50 °C and p H 2.0 were isolated from compost and decaying plant matter.
Strain ICP appeared to possess an inducible, high affinity transport system for carbon dioxide during growth under air (unlike any previously studied moderate thermophiles), but extensive oxidation of ferrous iron was not achieved even at enhanced carbon dioxide levels.
This lack of oxidation appeared to be the result of autotrophically-growth strain ICP having an apparent higher affinity for the end-product of iron oxidation, ferric iron (Ki 0.4 m M), than the substrate, ferrous iron (Km 0.5 m M).
In natural environments, thermophilic fungi are most commonly found in rapidly decomposing plant residues, where heat is generated through exothermic microbial activity.
Heat accumulation in a 5-cm layer of leaf litter is sufficient to create favourable conditions for thermophilic fungi, and temperature increase may even lead to ignition in stockpiles of hay, oil seeds or manure.This study has divided the most frequently isolated types of moderate thermophiles into three groups: isolates of Sulfobacillus thermosulfidooxidans (mol% G C 47-50), an isolate referred to as strain NAL and other closely related species (mol% G C 54-57), and the type previously referred to as strain TH3 (mol% G C 68).An enrichment culture was obtained that could efficiently solubilise a range of mineral sulphides at 48o C under air.Earlier reports of thermophilic fungi were the result of accidental contamination of organic materials incubated at elevated temperatures.These include the isolation of Mucor pusillus (=Rhizomucor pusillus) from bread in 1886, and Humicola lanuginosa (=Thermomyces lanuginosus) from potato slices in 1899 (from Johri et al..strains exhibited both higher thermal stability and tolerance to acidic conditions.The study highlights the vast potential of an untapped diversity of thermophilic fungi in the tropics., and only a small number of fungal species thrive at such high temperatures.As a result of increased interest in renewable sources of energy and biomaterials, fungi that are adapted to extreme environmental conditions have recently received special interest as sources of novel hydrolytic enzymes suitable for various technological applications.Genome sequences have been obtained for a large number of thermophilic fungi, such as Myceliophthora thermophila, Thielavia terrestris, Thielavia heterothallica, Chaetomium thermophilum, Thermomyces lanuginosus, T.A range of genes encoding lignocellulolytic enzymes in the acidophilic fungus Acidomyces acidothermus MEY-1 has been cloned and expressed.The enzymes were found to be thermotolerant and functional under acidic conditions.