Classification of fungi

The fungi are organized into phyla, however, this is still a controversial issue. We will adopt the simplified classification that mainly considers the types of spores formed during the life cycle of these organisms. The phyla are: chytridiomycota (chytridiomycetes or chytrid), zygomycota, ascomycota and basidiomycota. A typical example of a fungus are zygomycetes, like the black mold of bread.

There are also the so-called imperfect fungi, which received this name for not having the sexual phase of the life cycle. In general, fungi are characterized as heterotrophic eukaryotes, with cell walls, have glycogen as a reserve substance, reproduce by spores, have a body formed by hyphae, may have aerobic respiration or be facultative anaerobes. Taxonomically, fungi are closer to plants than animals, forming a monophyletic group, Eumycota (true fungi).

In the past, fungi had several classes, for example, the deuteromycota group, or imperfect fungi, but today it has no taxonomic value. Fungi can reproduce sexually or asexually, being organized into four groups.

Fungi are closer to plants than animals (Photo: depositphotos)

What are the four fungal classification groups?

The four groups or phyla are: chytridiomycota (chytridiomycetes or chytrids), zygomycota, ascomycota and basidiomycota.

Phylum Chytridiomycota

This phylum is represented by fungi from the aquatic environment where the zoospores can move in the water. In the evolution of the fungi, there was a loss of the scourge, favoring the occupation of the terrestrial environment by these organisms.

Citridiomycetes, also known as mastigomycetes (mastix: flagella and mycetos: fungus), can resemble amoebae in some stages of their life cycle and do not have the cell wall made up of chitin, but only cellulose and polysaccharides. They can also be divided into two distinct groups: Saprobes, which feed on the remains of plants and animals, and parasites, responsible for causing diseases in potatoes.

Phylum Zygomycota

Zygomycetes are fungi that, in general, are used in making soy sauce and hormones , such as contraceptives and anti-inflammatory drugs. Its fruiting body is a white colored fluff full of dark spots that are sporangia.

There are more than 1,000 species of this type of fungus and they can be found almost everywhere, acting as parasites in some animals or as decomposers. The best known representative of this phylum is Rhizobux, which causes molds in sweets, breads and fruits.

The fungus that causes mold in bread is from the phylum Zygomicota (Photo: depositphotos)

Phylum Ascomycota

Ascomycotas, or ascomycetes, comprise half of the known species of fungus. The most popular is yeast , associated with bakery yeast and the manufacture of products such as bread, alcohol and alcoholic beverages. Another well-known species is Penicillium, used in genetic studies, responsible for the production of penicillin and some cheeses. There are more than 32,000 species of this fungus and they are responsible for the formation of the sexual reproductive structures known as disgusting, hence its name.

Phylum Basidiomycota

Also known as basidiomycetes, they are the ones that produce the sexual structure called basidium, from which its name derives. It has more than 22,000 species and are better known as wood ears, mushrooms , coals and rust, both of which are responsible for causing diseases in plants. Some species are edible, while others are outright poisonous, such as Agaricius (known as champignon) and Amanita Muscaria.

Order

There are several orders in each phylum. Ascomycota phylum, orders: Neolectales, Pneumocystidales, Schizosaccharomycetales, Taphrinales, among others; phylum basidiomycota, orders: Auriculariales, Dacrymycetales, Sebacinales, Christianseniales, among others; phylum chytridiomycota, orders: Blastocladiales, Chytridiales, Monoblepharidales, among others and phylum zygomycota, orders: Harpellales, Dimargaritales, Endogonales, Entomophthorales, among others.

Reproduction of fungi

It can be sexual or asexual. In asexual processes, spores (n) are originated by mitosis and therefore are called asexual spores. In sexual processes, there is a fusion of haploid nuclei of different hyphae forming diploid zygotes. These suffer meiosis, giving rise to haploid spores, called sexed spores. In fungi, meiosis is always zygotic.

The mushrooms are part of the Phylum Basidiomycota (Photo: depositphotos)

What is an imperfect fungus?

They are called imperfect fungi, or deuteromycetes, fungi that do not have a sexual phase in their life cycle, because they lost it during evolution. By molecular analysis, it is known that most deuteromycetes can be classified as ascomycetes or, more rarely, as basidiomycetes. Deuteromycetes are no longer considered a valid taxonomic group.

Importance of fungi

Fungi are, for the most part, decomposers, also called saprobes (sapro = rotten) because they feed on decomposing organic matter, thus being fundamental in the recycling of organic matter . Despite this positive aspect of decomposition, this process is also responsible for the decay of food and wood, causing serious economic losses.

Many fungi are used in human food, in the manufacture of certain types of cheese , such as roquefort and gorgonzola. They are also manipulated by the pharmaceutical industry in the production of antibiotics, such as the species of Penicillium chrysogenum and P. notatum, used in the production of penicillin.

Some species of fungi live in mutualistic association with other organisms. Among mutualistic fungi, there are those that live associated with plant roots, forming mycorrhizae (roots that contain fungi).

Mycorrhizae are extremely important in ecosystems. Fungi absorb water from the soil, degrade organic matter and absorb released nutrients, transferring them in part to the plant, which thus grows healthy. The plant in turn, yields to the fungus certain sugars and amino acids that it needs as food. Some types of fungi can also act as parasites on plants and animals.

In plants, for example, the disease known as rust affects coffee plantations, wheat, among others. In animals, we can mention mycoses that affect human skin, thrush (infection in the mouth), vaginal candidiasis (sexually transmitted disease) and histoplasmosis (infection in the lungs).

resume

Fungi are beings capable of surviving in virtually all types of environments. They can act as parasites on plants or animals and feed on decomposing organic matter. Currently, there are more than 200,000 species of fungi worldwide and some of them have similar taxonomic characteristics. These species are classified in Philos, according to their evolutionary characteristics

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