1.1 decomposer of organic materials in nature, fungi

1.1 IntroductionFungi are essential part of the ecosystem. They have multiple roles in nature, asdominate decomposer of organic materials in nature, fungi recycle nutrients backinto their habitat or living symbiotically with other plants or animals. Generallyfound in moist, dark environment, and without the ability to photosynthesise,flamentous fungi cells forms long tubular flaments called hyphae, that spreadsto form mycelium, to absorb food and reproduce. During asexual reproduction,new aerial morphologies, such as conidiophores and fruiting bodies, are producedto disperse spores into the air and germinate in new locations. Hydrophobins aresmall amphipathic proteins which are produced and secreted by flamentous fungiduring its growth and development cycles. These proteins function to assist withthe formation of aerial hyphea, prevent wetting of the aerial spores to allow forefcient dispersal, protect the spores from the external environment and enhanceattachment to surfaces prior to infections. Hydrophobin proteins have attracted agreat deal of attention over the past decade, due to their unique properties whichcan provide a range of novel advancement in medical, biotechnology and surfacecoating applications.1.2 Hydrophobins: Discovery and historyThe fbrillar structures coating the surface of fungi spores were frst observed withtransmission electron microscopy in the 1960’s 1, 2, were not termed “hydrophobin”till 1991 by Wessels et al 3. The rodlet coating found on the surface of fungi sporesof Neurospora crassa was discovered to function as water repelling flm in 1978 byDempsey and Beever4. When comparing wild type spores with mutant sporeswhich did not form the rodlet coating, due to a gene knock out of Neurosporacrassa, the lack of the rodlet coating rendered the mutant spores easily wettable.The missing gene was designated “eas” due to the “easily” wettable phenotypeand the protein was appointed as EAS. The insoluble nature of the rodlet flmmade attempts at solublising the protein with commonly used denaturing bu?er challenging 4, 5. It was not until 1995, Templeton et al were able to solublisedthe rodlet flms with 100% tri?uroacetic acid and extract a 7 kDa protein foundto be the EAS gene product 6. The term “hydrophobin” was coined by duringthe discovery of characteristic proteins, SC1, SC3 and SC4, produced during theformation of aerial hyphae and fruiting bodies of Schizophyllum commune 3. Theproteins have a relatively high numbers of hydrophobic residues and contained eightcysteines organised in a conserved pattern. These characteristics are found in otherhydrophobin proteins produced by di?erent flamentous fungi 6–12.