Unicellular fungi and their role in nature

Unicellular organisms became known to man only with the advent of magnifying devices. However, today they are the basis of valuable genetic studies 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, let us consider which representatives are included in the category of the simplest fungi and what properties and features they possess.

Mushrooms unicellular and multicellular: general characteristic

Of all the five kingdoms of living nature, 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 are very differently arranged, therefore with them in general mistakes can not be.

And only mushrooms are such complex organisms that for a long time did not belong to any particular kingdom. Initially, they were considered plants that were simply devoid of chlorophyll. More recent studies have shown that in their decay products they contain urea, and the cell wall consists largely of chitin. At the same time, digestion is external, and many enzymes are similar to those produced by the organisms of mammals.

These signs clearly spoke of the fungi belonging to animals. In addition, it became known that unicellular mushrooms of the Myxomycetes 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 the fungi began to be attributed to a separate realm of wildlife. A common sign for their identification was:

• The presence of a unicellular multinucleate or multicellular mycelium;
• Hyphae - thin threads, capable of intertwining, forming a mycelium and a fruiting body;
• Heterotrophic method of nutrition;
• Chitin in the cell wall;
• Urea in the composition of the products of the decomposition of substances;
• Absence of plastids;
• Reproduction by means of spores.

In total today there are about 250 thousand species of these organisms. A significant part of them are unicellular fungi.

Classification of unicellular fungi

With such a variety there is a need for classification. Therefore, all single-celled fungi were systematized, examples of which can be cited, if we consider a complete classification.

There is no one for today, so they differ from one author to another. So, there are 4 main groups.

1. Deuteromycetes is another name for imperfect fungi. They do not have a sexual mode of reproduction. Representatives: sclerotium, rhizoctonia, many kinds of candida.
2. Chitridiomycetes are complex unicellular fungi, the mycelium of which is represented by long branching structures containing several nuclei. Representatives: olpidium, silhitrium, spilliformes, monoblofarids and others. Most lead an aquatic or semi-aquatic life, being parasites of marine and freshwater plants, animals.
3. Zygomycetes are typical unicellular fungi, in some representatives of mycelia with several weak septa. Representatives: mukor, trichomycetes, spinellus, zoopagilis and others. Among them there are soil inhabitants, and parasites of man, animals and plants.
4. Ascomycetes - most multicellular, but there are also single-celled fungi. Examples: yeast, morels, truffles, stitches, parmelia and others. They got their name for the peculiarities of the structure of the dispute, which are called ascospores. Some of the representatives lose their ability to reproduce during their lifetime and are referred to deuteromycetes, that is imperfect fungi.

Each department has its own characteristics and characteristics, and even more so the species are very diverse. The way of life is interesting, the economic importance is important. In addition, fungi play an important ecological role in nature.

Features of structure and lifestyle

Before answering the question: "Describe the role of unicellular fungi in nature," one should consider their structural features and lifestyle. After all, this will determine the importance they will have for surrounding organisms, including humans.

So, the features of the structure of unicellular fungi.

1. Mycelium is either not developed at all, or very weak. Can be multi-core or represented by a single cell with one core.
2. Reproduction is often asexual, although for many, the sexual process is also characteristic.
3. Water representatives form zoospores (chitridiomycota), which move freely in the water with the help of flagella. Ascomycetes have special organs for sporebinding bags, in which ascospores ripen. Their number does not exceed eight.
4. Some soil zygomycetes form mycorrhizas with the roots of the trees.
5. Imperfect mushrooms enter into symbiosis with bacteria, forming a useful tea mushroom.

In general, the structure of almost all fungi, as well as the internal cellular composition is almost identical. And it does not matter whether it is higher or imperfect. Therefore, at the heart of the classification is always the main feature - the method of reproduction.

Lifestyle Features:

1. The overwhelming majority are obligate or facultative parasites.
2. Many have adapted to life in water or soil.
3. Part of the representatives allocates a large number of enzymes to the environment in order to prepare food for themselves. Even without a branched mycelium, some organisms produce subtle rhizoids, which are attached to the substrate, and capture (suck) food.
4. Among the zygomycetes there are special representatives - zoopagilis. They got their name for a predatory way of life. They seize the larvae of insects, nematodes and other protozoa by sticky hyphae and eat them, digesting from the outside.
5. In the process of vital activity, many representatives (especially yeast) are able to produce valuable medicinal substances, enzymes, important chemical compounds.

To distinguish common features for everyone in the way of life is difficult, because the number of species is too large. Therefore, it is better to focus on the most frequently encountered and important for a person.

The process of reproduction

We have already clarified that the main distinguishing feature of the organisms under consideration is a way of reproduction of the offspring. Reproduction of unicellular fungi can be carried out in three ways:

• Sexual;
• Vegetative;
• Asexual.

Let's consider all the options in more detail.

1. Asexual reproduction implies the formation of spores within the special formations of sporangia. So, for example, in chitridia it is mobile zoospores, and in ascomycetes - ascospores of endogenous origin.
2. Vegetative for unicellular representatives implies budding. That is, one cell buds and becomes an independent organism. This is the case with yeast, which are generally considered secondarily unicellular fungi.
3. The sexual process is not the same for different species. However, there are three possible variants: heterogamy, oogamy and isogamy. In any case, the essence lies in the fusion of the sex cells with the formation of a zygote. Most often it is covered with a dense shell and experiences a state of rest for a while. After this, the mycelium begins to form and a new organism grows. Even in the case of multicellular representatives, there is no question of the existence of male and female parts. Just talk about the presence of the "+" and "-" sides of the mycelium, which merge with the formation of a dicarion.

Of course, there are also features that help identify some representatives. However, the general patterns of multiplication of unicellular fungi are exactly those described above.

Penicillium and its characteristics

The fact that penicillium is a unicellular fungus can not be said. The thing is that it belongs to the class of mold representatives, most of which are the simplest in organization. Therefore, it is often attributed to such features. However, penicillium itself, as well as his close friend, aspergillus - is the owner of a multicellular branching mycelium.

This fungus was discovered by Ernest Duchan in 1897. It was he who first drew attention to how in Arabia used an incomprehensible greenish coating for the healing of wounds of horses. Having examined its structure, the young man (and Duchene was only 23 years old) came to the conclusion that this organism is a fungus that possesses antibacterial properties, since it is capable of destroying eisericichu kol - one of the most pathogenic and pernicious bacteria.

For a long time no one listened to his discovery. In 1949, Fleming proved the antiseptic and antibacterial properties of this fungus, and Duchesne's merit was recognized, although after the latter's death.

The main ingredient that is used to make penicillin drugs is an antibiotic produced in the process of vital activity of the body.

Mold fungi

If we answer the question: "Describe the role of unicellular fungi in nature," then one can not help mentioning other mold representatives. After all, most of them settle on the soil, giving it a grayish or bluish hue in the form of a raid. In this case, decomposition of dead organic matter takes place. Therefore, in nature these fungi play the role of kind of nurses.

For a person, the following representatives are very important:

• Aspergillus;
• penicillium;
• "Noble rot";
• "Noble mold".

All of them are active participants in the process of making rare and tasty cheeses, wines, food additives, antibiotics and other valuable substances.

Mukor

The most typical representative of the organisms under consideration is flour. Single-celled fungus, which has a fairly large, branching mycelium, while formed by only one cell. There are no partitions in it. Refers to molds of the zygomycetes department.

It is difficult to call this mushroom useful, because its main merit is the spoilage of products and the formation of numerous mukoromycoses. However, some species are still used by man for making "Chinese yeast." This is a special starter, serving for cooking certain foods. For example, soy cheese. Some types of mukora are a source of enzymes and antibiotics.

On the soil and products of the colony of these fungi form a fluffy coating of beige and gray color, clearly visible to the naked eye.

Yeast

One-celled fungi include a representative such as a yeast fungus. However, these organisms should be considered secondarily unicellular, since they live in multi-colored colonies. Mycelium of each representative is unicellular, without partitions. But close cohabitation of several forms makes you think about multicellularity.

In general, yeast is a very useful mushroom. Not all, of course, but many of them. So, people from ancient times used them for baking bread, making wine and brewing. Another 6 thousand years ago BC. E. These creatures were used in Egypt everywhere.

Bread was baked using the remnants of the old leaven. 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 they are facultative parasites. That is, in the presence of oxygen they breathe freely, releasing carbon dioxide. But even under anaerobic conditions they do not disappear, oxidizing sugars (fermentation).

Different types of yeast can process a different substrate. Some can ferment only simple sugars, hexoses. But there are also those that process not only carbohydrates, but also proteins, lipids, carboxylic acids.

Human beings are important products that are released as a result of the vital activity of these fungi. Namely:

• Diacetyl;
• Isoamyl alcohol;
• Fusel oils;
• Dimethyl sulfide and others.

The combination of these substances determines the quality of the product. 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.

1. Trichophyton and microsporium are two species that cause serious skin diseases in humans.
2. Fungi of the genus Candida - cause the disease Candidiasis.
3. Dermatophytes - fungi that cause disease of the nail plate - onychomycosis.
4. Piedra, exophilus, malaziza - cause various lichen on parts of the body.
5. Black hari fungus causes a disease, manifested by a black touch on the language of man and animals.
6. Phytophthora is a dangerous fungus, damaging plants and causing the formation of black rot on the roots and leaves.

And this is still an incomplete list of those representatives who are pathogenic, harmful and extremely dangerous for health and harvest.

The role of unicellular fungi in nature

If you are faced with the task of such a plan: "Describe the role of unicellular fungi," then in the first place, you should identify the pluses. We mentioned a lot about them above:

• Are used in the chemical industry;
• In the food;
• Serve for the preparation of agricultural fodder;
• Are natural decomposers of organic substances, that is, nurses and so on.

But we should not forget about the disadvantages, which are also many. After all, most unicellular fungi are parasitic organisms.