Symbiotes are organisms that feed ... Organisms are symbionts

Symbiosis, or the mutually beneficial cohabitation of two or more organisms, has been known for a long time. But this does not in any way negate the fact that many of the nuances of this phenomenon have not yet been studied or studied poorly.

For the first time this amazing natural phenomenon was discovered by the Swiss scientist Schwendener in 1877. At that time he was just exploring lichens. To his deepest amazement it turned out that these organisms are compound, formed by colonies of fungi and unicellular simple algae. The very term "symbiosis" in the scientific literature appeared somewhat later. More precisely, he proposed in 1879 de Paris.

With the concept of people sorted out relatively quickly, but there was a question with the trophy. What do some types of symbiotic organisms eat at all? In the case of the same lichens, it was clear that algae live by photosynthesis, but that's where the nutrients from the fungal component come from? If you also do not know the answer to this question, we suggest you read our article.

General information

Modern scientists have found that symbionts are organisms that feed (most often) the same as that consumed by the dominant organism. However, this is a very rude and not very correct definition, and therefore it is necessary to describe a few more interesting cases in more detail.

You probably can give some examples yourself. So, useful bacteria for humans in large quantities are found in acidophilic yoghurts. People give these simplest beautiful habitats, and bacteria ensure the perfect functioning of our gastrointestinal tract.

By the way, the well-known Kutushov took advantage of this. The symbionts, the cultures of which he sells, provide a significant improvement in the functioning of the gastrointestinal tract, even in the elderly, who often have great problems with this.

Algae as the main symbionts

Biologists have long found out that without the involvement of algae, no symbiotic pair of organisms can do. And we are talking not only about water, but also about purely terrestrial organisms. They manage to enter into mutually beneficial relationships with each other, as well as with bacteria, fungi, multicellular organisms. It should be noted that the list of algae that are capable of symbiosis is rather limited.

Thus, mutually beneficial relationships with fungi can be established by representatives of a maximum of five or seven genera, and historically, the following are included in symbionts: Nostoc, Gloeocapsa, Scytonema and Stigonema.

About algae and sloths

Many people know that in the far selva of the Amazon there is a most remarkable animal in all respects. It was famous for its slowness and slowness. Of course, we are talking about sloths. But far from everyone knows that the color of these animals (dirty green, brown) does not appear as a result of the natural pigmentation of the coat, but thanks to symbiotic algae.

They live right in the wool of sloths and feed on the usual photosynthesis. The slothful gets an excellent camouflage color thanks to them. Frankly speaking, scientists have not been able to reach a unanimous conclusion that such coexistence gives the algae themselves. In this case, symbionts are organisms that are fed by substances produced by themselves in the process of photosynthesis.

Unusual forms of relationships between algae and other organisms

Lichens and sloths are an example of long-term stable relationships between the two forms of life. But not always symbionts, bacteria and algae, form such a strong and lasting alliance with other organisms. So, they often just settle on the surface of a living organism. Of course, there is no question of a full-fledged symbiosis in this case. This phenomenon is called epiphylation. The smallest film from the simplest algae often covers not only the shells of mollusks, but also the surface of the body of some waterfowl and marine animals. So, seaweed-epiphytes in large numbers settle even on giant whales.

Epiphytes - symbionts or parasites?

Scientists still can not agree on the point of view of the relationship between the epiphyte and the multicellular organism. Some believe that this phenomenon is better to accept as a primitive, primary version of symbiotic relationships.

For the sake of justice, it is difficult to agree with this point of view. Epiphytes do not directly damage the organisms on the surface of which they settle, that's just the benefit (visible in any case) from them is also not observed.

Harm from Epiphytes

Small water insects and mites, whose legs thickly adhere to epiphytes, become extremely slow, as they can not simply melt physically quickly. Higher aquatic plants, whose leaves "paid attention" to unicellular algae, often simply die from lack of sunlight. By the way, every aquarist certainly encountered this phenomenon. We can say that in this case symbionts are parasites, paradoxically as it may sound.

But! The phenomenon of epiphytism has been studied very, very badly. It is possible that these relationships actually benefit not only algae, but also multicellular organisms. The riddle is still waiting for its researcher. And what do the symbionts eat if they live inside the cells of a higher animal or plant?

Intracellular symbionts

Not so rare, symbionts can live inside the cells of their "master." If we talk about the same algae, then they are called endophytes. They form endosymbiosis, which is already much more complicated than the phenomena described above. Between partners, in this case, close, lasting and strong ties are already formed. Their main difference lies in the fact that such symbionts-protozoa are only revealed as a result of sufficiently detailed and complex cytological studies.

Important! Scientists have proven for a long time that the most important cellular organelles - mitochondria in animals and chloroplasts in plants - were formed in immemorial times precisely because of symbiotic relationships. Once upon a time they were independent organisms.

At some point, these intracellular symbionts moved to a completely "sedentary" existence within the living cell, and then became dependent on it, transferring control of their genome to its nucleus (in part). So you can safely say that all the now known forms of life that seek a mutually beneficial existence can all once become one with those organisms with which they have partnerships today.

How do the symbionts penetrate the cell?

How do microorganisms find themselves in the cells of higher animals and plants? Some species have specially designed mechanisms for this. And often they are not in the symbiont itself, but in the "receiving side". There is such a shallow water fern - azolla (Azolla). On the lower cavity of its leaves there are narrow passages that lead to caverns, specializing in the allocation of mucus. Here in these cavities and fall blue-green algae Anabena (Anahaena azollae), which swim into the caverns along with the current of water.

The fern grows, the channels overgrow, the algae remain in complete isolation. Scientists have long tried to create a colony of other species on the basis of azoles, but they have not achieved any success. One can say with confidence that the formation of a symbiotic connection is possible only in the case of a complete coincidence of a number of parameters. In addition, such an alliance has a pronounced specific specificity.

Thus, symbionts are organisms that feed on processes specific for their kind (nitrogen fixing microorganisms), separate valuable substances with a partner, but they need certain conditions that only he can provide.

Why is such coexistence advantageous?

We note that many nitrogen compounds are found inside the cavities of the azole. Blue-green algae that enter the fern organism not only actively absorb them, but also completely lose the ability to independently fix atmospheric nitrogen. The symbiont organisms respond reciprocally, supplying the fern with oxygen and some organic substances.

It should be noted that these symbionts do not undergo practically any changes in their internal organization. However, this is not the case in all cases of intracellular symbiosis. Most often, those algae that enter into mutually beneficial cooperation with other organisms are distinguished by a complete reduction of the cell membrane. For example, this happens in blue-green algae, which form a symbiotic relationship with some species of marine sponges.

Termites and intracellular symbionts

For a comparatively long time, all the scientists were perplexed, thinking about the processes of digestion of termites. How can this biological species prosper by eating only wood? More recently it was nevertheless found out that for the direct processing of wood pulp correspond to the smallest symbionts-bacteria, which are symbionts of protozoa that live in the intestines of the termites themselves. Such a complicated, but very effective scheme.

But researchers still did not understand where the insects take enough energy: after all, cellulose in any case is not very nutritious. In addition, they need a huge amount of nitrogen. There is no such volume in digested timber simply by definition. Recently, scientists from Japan came to a phenomenal result, which they obtained with a careful study of the genome of symbionts of flagellates living in the GIT of termites.

What happened in their genome?

There are many interesting things. In particular, scientists were able to detect not only those genes that are responsible for the production of an enzyme for the destruction of cellulose, but also those that are responsible for nitrogen fixation. The latter is the most complicated process of binding atmospheric nitrogen with the formation of those forms that can be assimilated by a plant or animal organism. This is extremely important, since the nitrogen produced in this way is used by termites and their flagellates for protein synthesis.

Simply put, in the case under consideration, symbionts are organisms that feed on wood consumed by termites. Symbions of symbionts (nitrogen-fixing bacteria of flagellates) are responsible for nitrogen fixation, without which neither termite nor its "guests" can live.

Legumes and symbionts

Since we remembered nitrogen-fixing bacteria, we can not but say about leguminous plants. They, as anyone who studied botany remembers, have a strikingly high content of vegetable protein. This circumstance also for a long time was extremely surprising to scientists. Beans managed to form a sufficient amount of protein, even in those conditions when there was practically no nitrogen in the soil!

It turned out that his arrival was provided by symbiont organisms. Yes-yes, they were all the same nitrogen-fixing bacteria, living comfortably in nodules on the roots of all leguminous plants. They extract precious nitrogen from the air, transferring it into a well-assimilated form.

Commercial use of symbionts

Not surprisingly, physicians have long been cultivating useful bacteria for humans. First it happened in the form of production of yogurts and other lactic acid products, but today the research has reached a whole new level.

Particularly well-known today are Kutushov's symbionts. What it is? At present, under this trademark, cultures of sour-milk organisms are sold, which improve the digestive processes.

All Kutushov symbionts (more precisely, their cultures) are based solely on ancient Mongolian recipes for dishes made from fermented milk products. So they really can improve your overall well-being and even appearance.

Developed by their scientist Kutushov. Symbionts in cultures are carefully chosen, they provide the human body with valuable amino acids and trace elements. It is through this that a positive effect is achieved.