An Overview to Lichens: The Nutrient Composition of Some Species

Özet

Lichens are slow-growing symbiotic organisms consisting of a fungus and an algae. Lichens count about 13.500 species growing throughout the world. Lichens have been used for medicinal purposes throughout the ages, and beneficial claims have to some extent been correlated with their polysaccharide content. Lichen polysaccharides which can be isolated in considerable yield such as the α-glucans, β-glucans, and galactomannans are generally expected to be of fungal origin. Several lichen species, such as Cetraria islandica and lobaria pulmonaria, have been used in traditional medicine since ancient times, to treat a variety of illnesses. All lichen species investigated so far produce polysaccharides in considerable amounts, up to 57%, and many of them have been shown to exhibit antitumour, immunostimulating, antiviral activity as well as some types of biological activity. There is a need for free-living algae, cyanobacteria and lichens mycobionts, grown in isolated cultures, to have the best advantage of organic nitrogen compounds.