Fungal hydrophobins, proteins as natural emulsifiers
Hydrophobins are proteins produced byfilamentous fungi that exhibit very peculiar properties. Theirbehaviour in solution resembles that of typical surfactantscharacterized by self-assembling into an amphipilicmembrane. Actually the hydrophobin self-assembly at thecell-wall–air interface plays a key role in the formation ofaerial hyphae and fruiting bodies by establishing a waterrepellentlayer. The interest in this class of proteins isincreasing because of their multiple and attractivepotential applications. Just to give an example,hydrophobins can be used to stabilize emulsions, and thisproperty might be extremely useful for pharmaceuticalapplications and in the food industry. We have purifiedand characterized the hydrophobin that is secreted in thecultural broth by the mycelia of the edible fungusPleurotus ostreatus. Higher amounts of the same proteinhave been obtained from the fungal mycelia and byrecombinant expression in E. coli. In this paper theemulsifying properties of the protein are also discussed.