Fungi are neither plants, animals nor bacteria. They form an independent group, including unicellular yeasts, multicellular, filamentous moulds and, of course, the classic basidiomycetes of the forest. Only the unicellular yeasts are categorised as microbes due to their size and for historical reasons.

 

The totality of all life probably originates from a small primordial cell, from which today's tree of life in all its diversity has developed. The branches of the tree group together similar organisms. Fungi are related to animals and plants and belong to the group of organisms with a cell nucleus (eukaryotes), unlike bacteria and archaea (prokaryotes).

 

Fungi are more closely related to the animal kingdom than to the plant kingdom. Researchers usually determine these relationships based on similarities between selected genes. The metabolism of fungi is also more similar to that of animals and humans: While plants obtain their energy for life from light (photosynthesis), in fungi it comes from carbon compounds, such as sugar.

Most fungi are multicellular and form an extensive, complexly branched network of elongated cells, the hyphae. This network (or mycelium) penetrates large parts of the soil. This enables these fungi to reach different, distant food sources and sometimes bridge distances of several kilometres. The stand fungus on the forest floor is only the fruiting body, a small part of the actual organism that spreads underground, hidden from us.

 

Fungi are indispensable and extremely important on our planet. They specialise in decomposing resistant natural materials from which plants are built. As "decomposers" (decomposers), they play an important role in our material cycle. They convert wood fibres, leaves and even bark into soil and thus create the basis for new life. Mycorrhizal fungi provide many plants with vital nutrients such as phosphorus and protect plants from diseases. Fungi even cleanse the soil of toxic pollutants such as agricultural pesticides.

 

Many types of fungi are microscopically small and are therefore, alongside bacteria and archaea, an important component of microbiology. Countless substances produced by fungi are very valuable for humans. For example, the first antibiotic, penicillin, was discovered in a mould fungus. The main producer of citric acid, which is used as a preservative and descaler, is also a mould. Furthermore, numerous fungal enzymes are used in the food, pharmaceutical and textile industries as well as in agriculture.