Single-celled organisms became known to man only with the advent of magnifying devices. However, today they are the basis of valuable genetic research for the accumulation of theoretical material on many issues of biochemistry, molecular biology, and genetics. There are different unicellular organisms. Mushrooms are one of them. Not all, of course, but quite a significant part. In this article, we will consider which representatives are included in the category of the simplest fungi and what properties and features they have.
Mushrooms unicellular and multicellular: general characteristics
Of all the five kingdoms of wildlife, mushrooms are the most unusual. The thing is that it is quite simple to determine the systematic position of a plant or animal. Bacteria and viruses have a completely different structure, so there can be no mistakes with them at all.
And only mushrooms are such complex organisms that for a long time did not belong to any particular kingdom. Initially, they were considered plants simply devoid of chlorophyll. Later studies showed that their decay products contain urea, and cellularwall consists largely of chitin. At the same time, digestion is external, and many enzymes are akin to those produced by mammalian organisms.
These signs clearly spoke of the belonging of mushrooms to animals. In addition, it became known that unicellular fungi of the myxomycete department (mucus) are able to move towards food and light under certain conditions. This once again proves that these organisms and animals had a common ancestor.
All this led to the fact that mushrooms began to be attributed to a separate kingdom of wildlife. The common feature for their identification was:
- presence of unicellular multinuclear or multicellular mycelium;
- hyphae - thin threads that can intertwine, forming a mycelium and a fruiting body;
- heterotrophic way of eating;
- chitin in the cell wall;
- urea in the composition of decomposition products of substances;
- lack of plastids;
- reproducing with spores.
Today there are about 250 thousand species of these organisms. A significant part of them are unicellular fungi.
Classification of unicellular fungi
With such diversity, there is a need for classification. Therefore, all unicellular fungi were systematized, examples of which can be given if we consider the full classification.
There is no single one today, so they are not the same for different authors. So, there are 4 main groups.
- Deuteromycetes is another name for imperfect fungi. They do not have sexual reproduction. Representatives: sclerotium, rhizoctonia, many types of candida.
- Chytridiomycetes are complex unicellular fungi, the mycelium of which is represented by long branching structures containing several nuclei. Representatives: olpidium, silchitrium, spizellomas, monoblepharids and others. Most lead an aquatic or semi-aquatic lifestyle, being parasites of marine and freshwater plants and animals.
- Zygomycetes are typical unicellular fungi, some representatives of mycelium with several weak septa. Representatives: mukor, trichomycetes, spinellus, zoopagalis and others. Among them there are both soil inhabitants and parasites of humans, animals and plants.
- Ascomycetes - most are multicellular, but there are also unicellular fungi. Examples: yeast, morels, truffles, lines, parmelia and others. They got their name for the structural features of the spores, which are called ascospores. Some representatives lose the ability to sexually reproduce during their lives and they are referred to as deuteromycetes, that is, imperfect fungi.
Each department has its own characteristics and characteristics, and the types are even more diverse. An interesting way of life, economic importance is important. In addition, mushrooms play an important ecological role in nature.
Features of the structure and lifestyle
Before answering the question: "Describe the role of unicellular fungi in nature", one should consider their structural features and imagelife. After all, it will depend on this what significance they will have for the surrounding organisms, including humans.
So, structural features of unicellular fungi.
- Mycelium is either not developed at all or very weak. It can be multinucleated or represented by one cell with one nucleus.
- Reproduction is often asexual, although many also have a sexual process.
- Aquatic representatives form zoospores (chytridiomycota), which move freely in the water with the help of flagella. Ascomycetes have special organs for sporulation of the sac, in which ascospores ripen. Their number does not exceed eight pieces.
- Some soil zygomycetes form mycorrhiza with tree roots.
- Imperfect mushrooms symbiose with bacteria to form the beneficial kombucha.
In general, the structure of almost all fungi, as well as the internal cellular composition, is almost identical. It doesn't matter if it's superior or imperfect. Therefore, the classification is always based on the main feature - the method of reproduction.
Lifestyle features:
- The vast majority are obligate or facultative parasites.
- Many have adapted to life in water or soil.
- Some representatives secrete a large amount of enzymes into the environment in order to prepare food for themselves. Even without a branched mycelium, some organisms release thin rhizoids, which both attach to the substrate and capture (suck) food.
- Among Zygomycetes there are special representatives - zoopagalis. OwnThey got their name for their carnivorous way of life. They capture the larvae of insects, nematodes and other protozoa with sticky hyphae and eat them, digesting them from the outside.
- In the process of life, many representatives (especially yeast) are able to produce valuable medicinal substances, enzymes, important chemical compounds.
It is difficult to distinguish common features for everyone in the way of life, because the number of species is too large. Therefore, it is better to dwell on the most common and important for a person.
Reproduction process
We have already specified that the main distinguishing feature of the organisms under consideration is the way of reproducing offspring. Reproduction of unicellular fungi can be carried out in three ways:
- sexual;
- vegetative;
- sexless.
Let's consider all the options in more detail.
- Asexual reproduction involves the formation of spores within special formations of sporangia. So, for example, in chytrids these are mobile zoospores, and in ascomycetes - ascospores of endogenous origin.
- Vegetative for unicellular representatives implies budding. That is, one cell buds and becomes an independent organism. This happens in yeast, which are generally considered secondary unicellular fungi.
- The sexual process occurs differently in different species. However, only three options are possible: heterogamy, oogamy and isogamy. In any case, the essence is the fusion of germ cells withthe formation of a zygote. Most often, it is covered with a dense shell and experiences a state of rest for some time. After that, mycelium begins to form and a new organism sprouts. Even in the case of multicellular representatives, the existence of male and female parts is out of the question. They just talk about the presence of "+" and "-" sides of the mycelium, which merge to form a dicarion.
Of course, there are features that help identify some representatives. However, the general patterns of reproduction of unicellular fungi are exactly the same as described above.
Penicill and its characteristics
The fact that penicillium is a unicellular fungus cannot be said. The thing is that it belongs to the class of mold representatives, most of which are the simplest in organization. Therefore, such features are often attributed to him. However, penicillium itself, as well as its close friend, aspergillus, is the owner of a multicellular branching mycelium.
This mushroom was discovered by Ernest Duchen in 1897. It was he who first drew attention to how in Arabia they used an incomprehensible greenish coating to heal the wounds of horses. After examining its structure, the young man (and Duchenne was only 23 years old) came to the conclusion that this organism is a fungus with antibacterial properties, as it is able to destroy coli, one of the most pathogenic and harmful bacteria.
For a long time no one listened to its discovery. In 1949 Fleming provedantiseptic and antibacterial properties of this fungus, and Duchenne's merit was recognized, though after the death of the latter.
The main component that is used to make penicillin is an antibiotic produced during the life of the body.
Mold mushrooms
If you answer the question: "Describe the role of unicellular fungi in nature", then we can not say about other mold representatives. After all, most of them settle on the soil, giving it a grayish or bluish tint in the form of a plaque. In this case, the decomposition of dead organic matter occurs. Therefore, in nature, these mushrooms play the role of a kind of orderlies.
The following representatives are very important for a person:
- aspergillus;
- penicill;
- "noble rot";
- "noble mold".
All of them are active participants in the process of making rare and delicious cheeses, wines, food additives, antibiotics and other valuable substances.
Mukor
The most typical representative of the organisms under consideration is mucor. A unicellular fungus that has a fairly large, branching mycelium, while being formed by just one cell. It has no partitions. Refers to mold fungi of the Zygomycetes department.
It is difficult to call this mushroom useful, because its main merit is food spoilage and the formation of numerous mucormycosis. However, some species are still used by humans to make"Chinese yeast". This is a special leaven that is used to prepare certain foods. For example, soy cheese. Some types of mucor are a source of enzymes and antibiotics.
On the soil and products, colonies of these fungi form a fluffy coating of beige and gray, clearly visible to the naked eye.
Yeast
Single-celled fungi also include such a representative as a yeast fungus. However, these organisms should be considered secondarily unicellular, since they live in multi-budding colonies. The mycelium of each representative is unicellular, without partitions. But the close cohabitation of several forms at once makes one think about multicellularity.
In general, yeast is a very useful mushroom. Not all, of course, but many of them. So, since ancient times, people have used them for baking bread, making wine and brewing. Another 6 thousand years ago BC. e. these creatures were used throughout Egypt.
The bread was baked using the leftovers of the old sourdough. This led to the degeneration of culture, it became completely genetically pure and homogeneous. Therefore, today there are such "breeds" of yeast that were not created by evolution in nature, but were the result of human economic activity.
An interesting feature of yeast is that it is a facultative parasite. That is, in the presence of oxygen, they freely breathe it, releasing carbon dioxide. But even under anaerobic conditions they do not disappear, oxidizing sugars (fermentation).
Different types of yeast can process different substrates. Some can only ferment simple sugars, hexoses. But there are those that process not only carbohydrates, but also proteins, lipids, carboxylic acids.
Those products that are excreted as a result of the vital activity of these fungi are important to a person. Namely:
- diacetyl;
- isoamyl alcohol;
- fusel oils;
- dimethyl sulfide and others.
The combination of these substances determines the quality of the products. This directly affects its organoleptic properties.
Parasitic unicellular representatives of fungi
Among the parasites, the most dangerous unicellular are those that cause fungal infections in humans and animals, as well as various molds and rot in plants.
- Trichophyton and microsporum are two species that cause serious skin diseases in humans.
- Mushrooms of the genus Candida - cause the disease candidiasis.
- Dermatophytes - fungi that cause disease of the nail plate - onychomycosis.
- Piedra, exophila, malaziza - cause various lichen on parts of the body.
- The black hari fungus causes a disease that manifests itself as a black coating on the tongue of humans and animals.
- Phytophthora is a dangerous fungus that infects plants and causes the formation of black rot on roots and leaves.
And this is still an incomplete list of those representatives that are pathogenic, harmful and extremely dangerous to he alth and crops.
The role of unicellular fungi in nature
If in front of youthe task is such a plan: "Describe the role of unicellular fungi", then first of all, the pluses should be identified. We mentioned them a lot above:
- used in the chemical industry;
- in food;
- serve for the preparation of agricultural feed;
- are natural organic decomposers, that is, orderlies and so on.
But also we should not forget about the minuses, which are also many. After all, most unicellular fungi are parasitic organisms.
