What are symbionts, saprotrophs, parasites, pathogenic

0

1322

Article rating

Kira Stoletova

Symbiont mushrooms are one of the most amazing forms of life. There are many types of organisms that can be called symbionts. The process of symbiosis in nature is important.

Features of symbiont mushrooms

Symbiont mushrooms

Mushrooms are a unique group of living organisms on our planet. The science of mycology studies them. Today we are interested in some of the most common representatives of the kingdom of Mushrooms - those of them that are capable of forming symbiotic associations with representatives of the kingdom of Flora.

Irina Selyutina (Biologist):

Modern science knows the following groups of mushrooms according to their feeding method:

1. Saprophytes, or saprotrophs, or microconsumers : they use organic compounds of dead tissues of both plants and animals for their nutrition. They play an important role in the biological cycle of substances in the biosphere.
2. Parasites: organisms whose way of life is very closely related to representatives of other species, inside or on the surface of whose bodies they live, feed and, in most cases, harm them in some way.
3. Symbionts: organisms of different species that enter into mutually beneficial cohabitation.

Symbionts are widespread throughout the globe. For a long time, scientists could not unravel the secret of mushrooms entering into a symbiotic union, but they managed to do it.

Classification

In nature, saprophytes have spread very widely and inhabited various niches: they can be found in large quantities both in soil and in water. In addition, they are found on the surface of any organism - human or animal. Most often they are located in cavities, especially in those that communicate with the outside space: the mouth, nose, vagina, rectum.

Doctors know that when it comes to human health, these bacteria and fungi behave in two ways depending on the conditions. If they live in a healthy body with a normal level of immune mechanisms, then they behave like typical saprophytes. Such microbes do not have a pathogenic effect on the body, existing peacefully in it, and do not provoke any harmful effects.

If the natural mechanisms of immunity are suppressed, then the saprophyte is able to behave atypically: the bacterium can move to other tissues or organs, where it begins to multiply, thereby causing diseases of different course and severity, such as meningitis, sepsis, etc.

One of the striking examples is Bacillus subtilis, which is always present in the gastrointestinal tract of people. Its presence has a certain benefit, since this bacterium is involved in the digestion process, facilitating the breakdown of proteins and carbohydrates. With its help, the body limits the growth of pathogenic microflora of the intestines and skin, suppresses the growth of microbes in wounds, etc.

But if a person is weakened by illness or any other factors, Bacillus subtilis begins to behave aggressively: it provokes food poisoning, causes eye infections, activates allergic reactions on the skin, etc. This dual behavior often raises the question: to the group of saprophytes or parasites take the hay stick? Knowing the main characteristics of saprotrophs, any specialist understands that it is an ordinary saprophyte.

Focusing on the main beneficial properties of Bacillus subtilis, it is used in many medications and food supplements. The role of Bacillus subtilis is irreplaceable in the fight against diseases in which antibiotics play a major role in therapy, but for various reasons they cannot be prescribed to the patient.

Parasites include those microorganisms that spend their entire life or a separate part of their life cycle inside the host, from whose living cells they extract everything they need for development. The host can be either an animal or a plant. A parasite always causes a deterioration in the health of its host, but the differences in this negative impact can be enormous: from minor diseases that do not prevent the affected plant or animal from living, to the death of the feeding organism.

To extract nutrients, parasites use juices, organic liquids, soft and hard tissues. Many species, as they reproduce and increase in population, can invade various organ systems, quickly causing irreversible consequences.

There are forms with obligate parasitism. This means that they can only live inside their host, and if the host dies, the parasite dies along with it. Such species are aimed at preserving the normal functioning of the host, and therefore rarely lead to death.

Parasites, in turn, are divided into two categories:

• Microparasites. Their entire life cycle takes place within one host, and this is where their offspring most often live.
• Macroparasites. They actively reproduce by spores and are transferred to new habitats, actively infecting new food sources.

Among parasitic life forms, there are many that cause diseases that are dangerous to humans, sometimes of an infectious nature.

In addition to standard parasitism, there is an erroneous one. This picture is quite rare, but often it is the source of fatal cases of infection. This happens in cases when the parasite enters the body of a biological species that is not its typical host, but for some reason does not die, but begins to grow and develop.

All human parasites according to the type of habitat are divided into ectoparasites (living on the skin, hair or nails) and endoparasites (living in internal organs and structures). Most of them show high resistance and variability, so treatment can last for a long time and dangerously frequent relapses.

Symbiosis process

Many fungi enter into a symbiotic relationship with their host plant. They entwine its roots with their hyphae. This formation is called “mycorrhiza” or “fungal root”. Mycorrhiza helps fungi obtain essential nutrients directly from the roots of the host plant: carbohydrates, oxygen and carbon dioxide. This does not harm the owner. The mycelium helps it obtain beneficial compounds from the soil, and also protects it from the effects of harmful microorganisms by releasing antibiotics into the environment.

Irina Selyutina (Biologist):

Mycologists distinguish the following types of mycorrhiza, which differ in the features of their structure:

• Ectotrophic: the hyphae of the fungus simply entwine the young root of the plant, forming mycorrhizal tubes or a kind of cover. In this case, although the hyphae penetrate the root rhizoderm, they spread only through the intercellular spaces and do not enter the cell cavity. In the case of the formation of this type of mycorrhiza, the root hairs of the plant atrophy - they are replaced by fungal hyphae and the root cap is reduced - it is similarly replaced by hyphae that have formed their own “cap”. The root is divided into zones with the formation of a Hartig network.
• Endotrophic: the hyphae of the fungus pass into the cell of the root cortex through the pores in its membrane and form clusters there that resemble tangles. At the same time, the mycorrhiza is faintly visible from the outside of the root.
• Ectoendomycorrhiza: represents something in between, combining the characteristics of previous types of mycorrhiza.

This forms an alliance beneficial for both organisms.

Thanks to numerous experiments by mycologists in a number of countries, by 1953 the existence of a relationship between representatives of various tree species and 47 species of fungi belonging to 12 genera had already been proven. Today it is known that more than 600 species of fungi are capable of participating in the formation of mycorrhiza. It also turned out that each mushroom can enter into a symbiotic relationship with not one, but several tree species. All records were broken by the marsupial fungus that forms sclerotia - Caenococcum granulosa. Under experimental conditions, he was able to form mycorrhiza with 55 species of tree species. By the way. The most specialized in relation to the formation of mycorrhiza is the larch butterfly (sublarch), capable of forming mycorrhiza only with cedar pine and larch.

Approximately 90% of all plants on our planet enter into symbiosis with fungi.

Mukor

This representative belongs to the generic branch of lower mold fungi of the class zygomycetes. In total, the class includes 60 species of various mushrooms. They can be found in the top layer of the earth; they can develop on food and organic parts. A certain amount of mucor can cause disease not only in animals, but also in humans.

But there are a number of mushrooms that are intended for use in the production of antibiotics or as a starter. Only those mucor mushrooms that have high enzymatic activity are used in production.

Reproduction of mucor fungi can be asexual or sexual. In asexual reproduction, the shell of a mature mushroom quickly and easily dissolves from moisture, and several thousand spores come out. Two branches take part in sexual reproduction: homothallic and heterothallic. They unite with each other to form a zygote, after which a hypha with an embryonic sporangium begins to germinate. People use Chinese mucor and snail mucor as leaven. Many people call these mushrooms Chinese yeast.

With the help of such yeast, people can obtain ethanol from potatoes.

Mucor can cause illness in humans and animals

Variety of symbiont mushrooms

Many edible and poisonous organisms known to man are symbionts:

• white (boletus);
• boletus;
• fox;
• oiler;
• saffron milk cap;
• boletus

Among the poisonous organisms, symbionts are the following:

• toadstools (white, pale, spring);
• fly agaric (red, toadstool, panther);

Such fungi are not able to exist without host plants, because from them they receive all the organic compounds they need, which plants form during photosynthesis.

Features of the symbiont organism

Fly agarics are found in all forests

A feature of such organisms is a kind of selectivity. An example of this is the well-known boletus, which is not able to grow in alder or aspen forests. The common fly agaric forms a mycelium that does not require a specific host, so it is found in any forest. But saffron milk caps and boletus are attached only to coniferous trees.

The ideal symbiont

Cenococcum is one of the most common and at the same time little studied fungi that form mycorrhiza. It is found both in the Arctic and in tropical latitudes. It is most often found in the roots of plants that can survive in extreme conditions. It forms ectomycorrhiza with a huge number of gymnosperms and angiosperms, as well as some ferns.

Research has revealed that this representative of the fungal kingdom produces few enzymes that destroy plant tissue. These enzymes are found mainly in common fungi that decompose organic matter for specific purposes. Coenococcum actively forms proteins that are integrated into the cells of the host plant and pump water there. Since this type of protein is activated during drought, it is not surprising that trees form a symbiosis with this particular organism - it helps them obtain water at a time when it is extremely scarce.

Saprophytes

Both bacteria and fungi are saprophytes. Bacteria belonging to this group feed on organic matter from dead organisms. The group of saprotrophs includes lactic acid, soil, butyric acid bacteria and others. This type of fungi includes organisms that develop on humus of plant origin. They can be divided into two groups - edible and inedible.

Suitable for food

Examples of mushrooms that are not harmful to health:

• Champignon;
• raincoats;
• umbrellas;
• morels;
• dung beetles;
• lines (after pre-processing);
• cystoderm;
• cobwebs.

Unfit for food

These organisms should not be eaten:

• pigs;
• Helvelians;
• pale toadstools;
• spring toadstools;
• white toadstools.

Interesting facts about symbiont mushrooms

A characteristic feature of the fungi that form mycorrhiza is that they cannot be grown under artificial conditions. Their mycelium is capable of being in the soil, absorbing and transferring nutrients, but will not form fruiting bodies. Without a certain type of tree, such mushrooms do not bear fruit.

The host plant will grow poorly, develop slowly, and eventually die if there is no symbiont fungus in the soil nearby. An example of this is pine seedlings, which grow much faster if spores of a certain type of fungus get into the soil.

Sometimes a symbiosis occurs between mushrooms and ants. Insects feed on nutritious hyphae, creating entire “mushroom farms” underground. This is beneficial for mushrooms, because ants generously fertilize the soil.

Edible and inedible species

Among the variety of saprotrophs, lamellar, marsupial and tubular species, which are among the highest, and imperfect molds and yeasts stand out.

Some marsupial, lamellar and tubular saprotrophs are suitable for human consumption. So, edibles include:

Not suitable for consumption and are poisonous:

Almost all types of yeast are used in the food industry and winemaking, and a representative of molds, penicillium, is a source of raw materials for the production of antibiotics.

The benefits of symbiosis

Mycorrhiza is a means of communication between plants. When something that can harm the plant appears in the environment, the mycelium, through chemical compounds, “sends” information about this to other mushrooms, and they meet the pest already prepared. In some ways, this is reminiscent of the transmission of information through the human nervous system. Any forest is a giant information network.

The benefits of symbiosis are as follows:

1. Symbiosis helps by increasing the adaptation (especially to unfavorable conditions) of the organism to the environment.
2. With its help it will be possible to increase the yield of cultivated plants.
3. Thanks to symbiosis, new groups of organisms (for example, lichens) can form.