Yeasts are unicellular fungi. What do yeast synthesize

Yeast is a fungus whose cells are microscopic in size (about 5 microns) and bud, forming a kind of colony. Yeast usually does not form mycelium. The shape of yeast cells is spherical.

In nature, yeast lives on the surfaces of fruits, flowers, they are present in the surface layers of the soil, the digestive tract of some insects, etc.

Yeasts are not a single taxonomic group of fungi. Yeasts include individual representatives of two divisions of fungi - ascomycetes and basidiomycetes. Yeast can be considered a special life form that has arisen in different types of fungi. There are more than 1000 types of yeast in total.

Yeasts are considered secondary unicellular organisms. This means that their ancestors were multicellular forms of fungi, which later became single-celled. Currently, there are peculiar "transitional" forms. So some fungi at some stages of the life cycle have signs of yeast, and at others they form a multicellular mycelium.

Budding is essentially the vegetative reproduction of yeast, i.e., the formation of spores. A bulge forms on the parent cell, which gradually grows, turns into an adult cell and can be separated from the parent cell. When the cells bud, the yeast looks like branching chains.

In addition to vegetative reproduction, yeast has a sexual process, when two yeast cells merge, a diploid cell is formed, which subsequently divides, forming haploid spores.

Yeast-ascomycetes differ from yeast-basidiomycetes in their life cycle, synthesized substances, features of budding, etc.

Nutrition of yeast cells is mainly carried out by the fermentation of low molecular weight carbohydrates (sugars). Sugars are fermented by yeast to alcohol and carbon dioxide. In this case, energy is released that goes to the vital processes of yeast.

Fermentation is anaerobic respiration, that is, obtaining energy without oxygen. However, yeast can also breathe oxygen. Thus, their anaerobicity is facultative (optional). When yeast breathes oxygen, it releases carbon dioxide but does not ferment sugars to alcohols. However, if there are a lot of sugars, then the yeast will ferment it even in the presence of oxygen.

The yeast fermentation process is used by man. In baking, the carbon dioxide formed by yeast makes the dough more porous. The formation of alcohol by yeast is used in winemaking and brewing. Also, in the course of their metabolism, yeast forms other substances (various oils, alcohols, etc.), which give the finished food products a special taste.

Man has learned to use yeast since ancient times. Their use in ancient Egypt is noted. However, the fact that these microscopic fungi provide the rise of the test or the formation of alcohol, people then did not know. Yeast was first observed by A. Leeuwenhoek (in 1680), then they were described by Charles Cagnard de La Tour (1838). However, only in 1857, L. Pasteur finally proved that organisms provide fermentation in raw foods, and this is not just a chemical reaction.

Certain types of yeast can cause disease.

Yeasts are fungi that exist throughout the entire life cycle or most of it in the form of separate single cells. Due to their unicellular structure, yeasts have a higher metabolic rate than filamentous fungi due to their relatively larger cell surface area. Yeast grows and reproduces at a high rate, causing significant changes in the environment. Historically, yeasts have always been considered separately from other fungi, since the methods of their study are more similar to bacteriological than to mycological.

Yeast-like stages are found in various groups of fungi, not only in the Saccharomycetaceae family. Based on the method of sexual reproduction, yeasts are divided into groups located in different classes of fungi - marsupial and basidial, and yeasts in which the sexual cycle is not found are classified as imperfect fungi (deuteromycetes). Thus, yeast is not a taxonomic, but rather a biotechnological term. There are no phytopathogenic species in the Saccharomycetaceae family; all saccharomycete yeasts are saprotrophs.
The body of yeast is very different from that of most fungi, as it consists of only one cell and therefore does not form mycelium. For the first time they were examined under a microscope by the Dutch scientist Leeuwenhoek. However, his contemporaries did not understand the significance of this discovery and it took about 150 years for scientists to understand the essence of these microorganisms and classify them as fungi.

Meanwhile, mankind has long used yeast for the preparation of alcoholic beverages and in bread baking. Archaeological excavations in Egypt and ancient Babylon have discovered the remains of breweries and bakeries that were built almost 6 thousand years before the new era. According to ancient Greek legends, the god Dionysus gave people the art of making wine.
In many languages, the name of yeast refers to the fermentation process it causes. Their Russian name comes from the word tremble, tremble, which characterize the state of fermenting wort or rising dough.
For the first time, the connection between fermentation and yeast was scientifically explained by the founder of microbiology, L. Pasteur. He established that fermentation replaces respiration for yeast. His saying is known: "Fermentation is life without air."
Yeast reproduction is very original: a small protrusion appears on the cell, it grows (it turns out to be a kidney) and finally turns into an independent cell and can separate. This process is called yeast budding.

About 500 types of yeast are known in nature. We come across many of them in everyday life. Yeast is divided into baker's, beer and wine. In baking, for example when we bake pies. We use yeast to make the dough rise. Yeast is used in winemaking, where the fermentation process is necessary. The use of yeast in brewing is of great importance.

Yeast has always been the constant companions and friends of man.

This is interesting

About a hundred years ago, at the foot of Elbrus, in the villages of the highlanders-Karachays, there was a custom. A leather waterskin filled with milk was thrown out into the street and left to lie there for some time. Everyone who passed by had to kick the wineskin with his foot. The boys especially liked this procedure. They rolled him on the ground, kicked him, mounted him. Physical exercises were prescribed to the wineskin not by chance. In addition to milk, sourdough was also placed in it - kefir "grains". When the waterskin was kicked, the fermenting liquid was agitated. The curdled milk became homogeneous.

In those years, the world did not yet know kefir. Only the mountaineers knew. They did not disclose the secret of kefir "grains". This is what religion required. However, no secret is eternal. Little by little, information began to leak out, and gradually they got acquainted with kefir, first in Russia, and then all over the world. A craze for a fashionable drink began, which has not ended to this day.

Several stories are told related to the disclosure of the secret. There are horse racing, chasing and kidnapping beauties. It seemed to me more plausible version of the Cossack N. Sigalova from the village of Krymskaya, which she described in a small book at the end of the century.
At the insistence of doctors, Sigalova was forced to leave her native places and go to the waters in Pyatigorsk for the treatment of a severe pulmonary disease. Changing places did not bring the desired result. The unfortunate woman had already completely lost hope for healing when she met the highlanders who had come to the market in Pyatigorsk. I learned from them that in the villages they treat lung diseases with kefir. The highlanders told something, but they refused to bring a drink: it is forbidden by the Koran.
Now, if the Russian herself went to the village ...

There was no choice, and Sigalova went to Budukeevsky aul, where an old Circassian woman named Fatimat lived. She took the patient to boarding school. I drank kefir. Gradually, the women became friends, and Fatimat entrusted the guest to cook kefir herself. In the meantime, the patient began to get better. Decreased cough. Breathing became free. The sputum came out more easily. Sigalova spent several months in the village. At parting, Fatimat gave her ward several hundred kefir "grains".

Having believed in the healing power of kefir, the recovered woman began to send the leaven to doctors in different cities. Medicine has confirmed the beneficial effect of kefir on the human body. A drink from the Caucasus soon came to exhibitions in St. Petersburg, Warsaw. It was shown in Paris and Chicago. At first, the price of kefir "grains" was high. They paid ten rubles for a spoon. But after some time they began to sell bags, at a ruble per pound.

How kefir "grains" originated is still unclear. They think that they were found in an insufficiently scraped waterskin, where milk was poured for fermentation. They look like lumps of rice porridge. This is a symbiosis - the peaceful coexistence of a lactic acid microbe and a yeast fungus. The microbe ferments the milk, turning it into curdled milk. Yeast ferments milk sugar. Carbon dioxide is released. It loosens the milk clot of curdled milk. It becomes uniform.

There is another type of symbiosis, where yeast fungi participate - "kombucha". In alliance with a yeast fungus, there is not a lactic acid microbe, but an acetic acid bacterium. Together they form a jellyfish-like creature that swims in the sweet tea solution. Sugar is fermented to alcohol. Alcohol - to acetic acid. Tea provides nitrogen nutrition to the fungus.
The pleasant, sour drink was spreading wider and wider, when suddenly a hail of accusations rained down. Serious concerns have been raised about the carcinogenicity of tea kvass. It was said to cause stomach cancer. Kombucha connoisseur Professor B. Barabanchik conducted a special study. It turned out that the patients confused the cause with the effect. Facts were judged. A person began to drink tea "kvass", and subsequently he was diagnosed with cancer.
In fact, a person begins to drink tea “kvass” because he already has cancer. And at the same time, the acidity of gastric juice is lowered almost to zero. And a person wants more and more sour. So "he drinks a sour and pleasant drink, born of a fungus and a bacterium.

But, of course, the most important yeast is not kefir or tea, but baker's. From a human point of view, of course. Annually they require 700 thousand tons. Humanity has been using their lifting power for so long that they have already lost their wild relatives. Only cultural yeast remained. These are now shaking. They try to create ideal conditions. Not only do they fertilize them with all kinds of salts (plants after all!), But they also add juices. Cucumber, watermelon and even pumpkin. In addition, carrots, potatoes and ... peas! Juices are especially needed when growing yeast from spores. In infancy, every organism requires special care and attention. Yeast is no exception. Then, when they grow, they need a lot of air. It is blown through from below, and then the yeast mass in the vats is agitated, like boiling borscht in a camp soldier's kitchen.

Brewer's yeast is a special article. They are useful not only because they give beer, but even more because they contain vitamins of group B. For weakened people and those who have caught a cold, brewer's yeast is prescribed first of all. The medicine is harmless, trouble-free, only requires skillful handling. Anyone who goes to the brewery for the first time does not know what trials await him on the way back. He is poured a jar of yeast at the factory. They ask: "Full or half?" “Full,” nods the cold. Request completed. With a precious burden, the poor fellow hurries home. If the matter takes place in the summer, then he soon finds that the yeast overflows. It's warm, and they have developed a vigorous activity. Carbon dioxide foams the liquid mass. And she stubbornly climbs out of the can.
Finally, the owner of the medicine catches himself thinking that it is possible to cool the treasure, and sticks the jar under the stream of water in the street column. This calms down the dispersed fungal cells. The foamy mass shrinks, decreases in volume. Now the victim is anxiously watching how much medicine will remain in the jar. Is it possible to go to the factory again?

In recent years, opinions about yeast have been divided. Some are for, others are against. Those in favor have tested the power of yeast on mice. The mice were divided into two groups. One received normal food, the other added yeast. The first ones went their way in life, meeting the usual deadlines. The second survived them almost twice. They also gave birth. So, it seems that yeast is the companion of centenarians?
Let's hear the other side now. They make no less compelling arguments. Of course, yeast treats nerves and colds. But the proteins in yeast are very unusual. Not the same as in milk and meat. Especially amino acids. In addition, there are also toxic fatty acids. Many poorly studied biologically active substances.

Mushrooms are ancient heterotrophic organisms that occupy a special place in the general system of living nature. They can be both microscopically small and reach several meters. They settle on plants, animals, humans or on dead organic remains, on the roots of trees and grasses. Their role in biocenoses is great and varied. In the food chain, they are decomposers - organisms that feed on dead organic residues, subjecting these residues to mineralization to simple organic compounds.

Mushrooms play a positive role in nature: they are food and medicine for animals; forming a fungus root, help plants absorb water; As a component of lichens, fungi provide a habitat for algae.

Mushrooms are chlorophyll-free lower organisms, uniting about 100,000 species, from small microscopic organisms to such giants as tinder fungi, a giant puffball and some others.

In the system of the organic world, fungi occupy a special position, representing a separate kingdom, along with the kingdoms of animals and plants. They are devoid of chlorophyll and therefore require ready-made organic matter for nutrition (they belong to heterotrophic organisms). By the presence of urea in the metabolism, in the cell membrane - chitin, a reserve product - glycogen, and not starch - they approach animals. On the other hand, in the way they feed (by absorbing, not swallowing food), by unlimited growth, they resemble plants.

Mushrooms also have features that are unique to them: in almost all mushrooms, the vegetative body is a mycelium, or mycelium, consisting of filaments - hyphae.

These are thin, like threads, tubes filled with cytoplasm. The threads that make up the mushroom can be tightly or loosely intertwined, branched, grow together with each other, forming films like felt or bundles visible to the naked eye.

In higher fungi, the hyphae are divided into cells.

Fungal cells can have from one to several nuclei. In addition to nuclei, there are other structural components in cells (mitochondria, lysosomes, endoplasmic reticulum, etc.).

Structure

The body of the vast majority of fungi is built from thin filamentous formations - hyphae. Their combination forms a mycelium (or mycelium).

Branching, the mycelium forms a large surface, which ensures the absorption of water and nutrients. Conventionally, mushrooms are divided into lower and higher. In lower fungi, hyphae do not have transverse partitions and the mycelium is a single highly branched cell. In higher fungi, the hyphae are divided into cells.

The cells of most fungi are covered with a hard shell; zoospores and the vegetative body of some protozoan fungi do not have it. The cytoplasm of the fungus contains structural proteins and enzymes, amino acids, carbohydrates, and lipids not associated with cell organelles. Organelles: mitochondria, lysosomes, vacuoles containing reserve substances - volutin, lipids, glycogen, fats. There is no starch. A fungal cell has one or more nuclei.

reproduction

Fungi have vegetative, asexual and sexual reproduction.

Vegetative

Reproduction is carried out by parts of the mycelium, special formations - oidia (formed as a result of the breakdown of hyphae into separate short cells, each of which gives rise to a new organism), chlamydospores (they are formed in much the same way, but have a thicker dark-colored shell, tolerate adverse conditions well), by budding of mycelium or individual cells.

For asexual vegetative reproduction, special devices are not needed, but not many, but few descendants appear.

With asexual vegetative reproduction, the cells of the thread do not differ from their neighbors, grow into a whole organism. Sometimes, animals or environmental movement tear the hyphae apart.

It happens that when adverse conditions occur, the thread itself breaks up into separate cells, each of which can grow into a whole mushroom.

Sometimes growths form on the thread, which grow, fall off and give rise to a new organism.

Often, some cells build up a thick shell. They can withstand desiccation and remain viable for up to ten years or more, and germinate under favorable conditions.

In vegetative reproduction, the DNA of the offspring does not differ from the DNA of the parent. With such reproduction, special devices are not needed, but the number of offspring is small.

asexual

During asexual spore reproduction, the filament of the fungus forms special cells that create spores. These cells look like branches that are unable to grow and separate spores from themselves, or like large bubbles inside which spores form. Such formations are called sporangia.

In asexual reproduction, the DNA of the offspring does not differ from the DNA of the parent. Less substances are spent on the formation of each spore than on one descendant during vegetative propagation. Asexually, one individual produces millions of spores, so the fungus is more likely to leave offspring.

sexual

During sexual reproduction, new combinations of characters appear. In this reproduction, the DNA of the offspring is formed from the DNA of both parents. Fungi combine DNA in different ways.

Different ways to ensure DNA integration during sexual reproduction of fungi:

At some point, the nuclei fuse, and then the DNA strands of the parents, exchange pieces of DNA and separate. In the DNA of the descendant are areas received from both parents. Therefore, the descendant is somewhat similar to one parent, and in some ways to the other. A new combination of traits can reduce and increase the viability of offspring.

Reproduction consists in the fusion of male and female gametes, resulting in the formation of a zygote. In fungi, iso-, hetero- and oogamy are distinguished. The reproductive product of lower fungi (oospore) germinates into a sporangium in which spores develop. In ascomycetes (marsupials), as a result of the sexual process, bags (asci) are formed - unicellular structures, usually containing 8 ascospores. Bags formed directly from the zygote (in lower ascomycetes) or on ascogenous hyphae developing from the zygote. In the bag, the nuclei of the zygote merge, then the meiotic division of the diploid nucleus and the formation of haploid ascospores occur. The bag is actively involved in the distribution of ascospores.

For basidiomycetes, a sexual process is characteristic - somatogamy. It consists in the fusion of two cells of the vegetative mycelium. The sexual product is the basidium, on which 4 basidiospores are formed. Basidiospores are haploid, they give rise to haploid mycelium, which is short-lived. By fusion of the haploid mycelium, a dikaryotic mycelium is formed, on which basidia with basidiospores are formed.

In imperfect fungi, and in some cases in others, the sexual process is replaced by heterocariosis (diversity) and the parasexual process. Heterokaryosis consists in the transition of genetically heterogeneous nuclei from one segment of the mycelium to another by the formation of anastomoses or fusion of hyphae. The fusion of nuclei does not occur in this case. The fusion of nuclei after their transition to another cell is called a parasexual process.

The filaments of the fungus grow by transverse division (the filaments do not divide along the cell). The cytoplasm of neighboring cells of the fungus is a single whole - there are holes in the partitions between the cells.

Nutrition

Most mushrooms look like long filaments that absorb nutrients from the entire surface. Mushrooms absorb the necessary substances from living and dead organisms, from soil moisture and water from natural reservoirs.

Mushrooms secrete substances that break the molecules of organic substances into parts that the fungus can absorb.

But under certain conditions, it is more useful for the body to be a thread (like a mushroom), and not a lump (cyst) like a bacterium. Let's check if this is so.

Let's follow the bacterium and the growing filament of the fungus. A strong sugar solution is shown in brown, a weak one is light brown, and water without sugar is shown in white.

It can be concluded that a filamentous organism, growing, can end up in places rich in food. The longer the thread, the greater the supply of substances that saturated cells can spend on the growth of the fungus. All hyphae behave like parts of one whole, and the fungus sections, once in food-rich places, feed the entire fungus.

mold mushrooms

Mold fungi settle on moistened remains of plants, less often animals. One of the most common fungi is mucor, or capitate mold. The mycelium of this fungus in the form of the thinnest white hyphae can be found on stale bread. The hyphae of the mucor are not separated by septa. Each hypha is one highly branched cell with several nuclei. Some branches of the cell penetrate the substrate and absorb nutrients, others rise up. At the top of the latter, black rounded heads are formed - sporangia, in which spores are formed. Mature spores are spread by air currents or with the help of insects. Once in favorable conditions, the spore germinates into a new mycelium (mycelium).

The second representative of mold fungi is penicillium, or gray mold. Mycelium penicilla consists of hyphae separated by transverse partitions into cells. Some hyphae rise up, and branchings resembling brushes form at their end. At the end of these branches, spores are formed, with the help of which the penicillium multiplies.

yeast mushrooms

Yeasts are single-celled immobile organisms of oval or elongated shape, 8-10 microns in size. They do not form true mycelium. The cell has a nucleus, mitochondria, many substances (organic and inorganic) accumulate in vacuoles, redox processes occur in them. Yeasts accumulate volutins in cells. Vegetative propagation by budding or division. Sporulation occurs after repeated reproduction by budding or division. It is made easier with a sharp transition from abundant nutrition to a small one, with the supply of oxygen. In the cell, the number of spores is paired (usually 4-8). In yeast, the sexual process is also known.

Yeast fungi, or yeast, are found on the surface of fruits, on plant residues containing carbohydrates. Yeasts differ from other fungi in that they do not have a mycelium and are single, in most cases oval cells. In a sugary environment, yeast causes alcoholic fermentation, as a result of which ethyl alcohol and carbon dioxide are released:

C 6 H 12 O 6 → 2C 2 H 5 OH + 2CO 2 + energy.

This process is enzymatic, proceeds with the participation of a complex of enzymes. The released energy is used by yeast cells for life processes.

Yeast reproduces by budding (some species by fission). When budding, a bulge resembling a kidney is formed on the cell.

The nucleus of the mother cell divides, and one of the daughter nuclei passes into a bulge. The bulge grows rapidly, turns into an independent cell and separates from the mother. With very rapid budding, the cells do not have time to separate, and as a result, short fragile chains are obtained.

At least ¾ of all fungi are saprophytes. The saprophytic mode of nutrition is associated mainly with products of plant origin (the acidic reaction of the environment and the composition of organic substances of plant origin are more favorable for their life).

Symbiont fungi are associated mainly with higher plants, bryophytes, algae, less often with animals. An example would be lichens, mycorrhiza. Mycorrhiza is the cohabitation of a fungus with the roots of a higher plant. The fungus helps the plant to assimilate hard-to-reach humus substances, promotes the absorption of mineral nutrition elements, helps with carbohydrate metabolism with its enzymes, activates the enzymes of the higher plant, and binds free nitrogen. From the higher plant, the fungus apparently receives nitrogen-free compounds, oxygen, and root secretions that promote the germination of spores. Mycorrhiza is very common among higher plants; it is not found only in sedge, cruciferous and aquatic plants.

Ecological groups of fungi

soil mushrooms

Soil fungi are involved in the mineralization of organic matter, the formation of humus, etc. In this group, fungi are distinguished that enter the soil only during certain periods of life, and fungi of the rhizosphere of plants that live in the zone of their root system.

Specialized soil fungi:

• coprophylls- mushrooms that live on soils rich in humus (dung heaps, places where animal droppings accumulate);
• keratinophils- mushrooms that live on hair, horns, hooves;
• xylophytes- mushrooms that decompose wood, among them there are destroyers of living and dead wood.

house mushrooms

House mushrooms - destroyers of wooden parts of buildings.

aquatic mushrooms

These include the group of mycorrhizal symbiont fungi.

Mushrooms that develop on industrial materials (on metal, paper and products from them)

cap mushrooms

Hat mushrooms settle on humus-rich forest soil and from it get water, mineral salts and some organic substances. Part of the organic matter (carbohydrates) they receive from trees.

Mushroom is the main part of every mushroom. Fruiting bodies develop on it. The cap and stem consist of mycelium filaments tightly adjacent to each other. In the stem, all the threads are the same, and in the cap they form two layers - the upper one, covered with a skin colored with different pigments, and the lower one.

In some mushrooms, the lower layer consists of numerous tubules. Such mushrooms are called tubular. In others, the lower layer of the cap consists of radially arranged plates. Such mushrooms are called lamellar. On the plates and on the walls of the tubules, spores are formed, with the help of which the fungi multiply.

Hyphae of the mycelium braid the roots of trees, penetrate into them and spread between the cells. Between the mycelium and the roots of plants, a cohabitation useful for both plants is established. The fungus supplies plants with water and mineral salts; replacing the root hairs on the roots, the tree yields to it some of its carbohydrates. Only with such a close connection of the mycelium with certain tree species is it possible for the formation of fruiting bodies in cap mushrooms.

Spore formation

In the tubules or on the plates of the cap, special cells are formed - spores. Ripened small and light spores spill out, they are picked up and carried by the wind. They are carried by insects and slugs, as well as squirrels and hares that eat mushrooms. The spores are not digested in the digestive organs of these animals and are thrown out along with the droppings.

In moist, humus-rich soil, fungal spores germinate, from which mycelium filaments develop. Mycelium, arising from a single spore, can form new fruiting bodies only in rare cases. In most species of fungi, fruiting bodies develop on myceliums formed by merged cells of filaments originating from different spores. Therefore, the cells of such a mycelium are binuclear. The mushroom picker grows slowly, only having accumulated reserves of nutrients, it forms fruiting bodies.

Most species of these fungi are saprophytes. They develop on humus soil, dead plant residues, some on manure. The vegetative body consists of hyphae that form a mycelium located underground. In the process of development, umbrella-like fruiting bodies grow on the mycelium. The stump and hat consist of dense bundles of mycelium filaments.

In some mushrooms, on the underside of the cap, plates diverge radially from the center to the periphery, on which basidia develop, and in them spores are a hymenophore. Such mushrooms are called lamellar. Some species of fungi have a veil (film of infertile hyphae) that protects the hymenophore. When the fruiting body ripens, the veil breaks and remains in the form of a fringe along the edges of the cap or ring on the leg.

In some fungi, the hymenophore has a tubular shape. These are tubular mushrooms. Their fruiting bodies are fleshy, quickly rot, easily damaged by insect larvae, eaten by slugs. Cap mushrooms reproduce by spores and parts of the mycelium (mycelium).

The chemical composition of mushrooms

In fresh mushrooms, water makes up 84-94% of the total mass.

Mushroom proteins are digested only by 54-85% - worse than the proteins of other plant products. Assimilation is hindered by the poor solubility of proteins. Fats and carbohydrates are digested very well. The chemical composition depends on the age of the fungus, its condition, species, growing conditions, etc.

The role of mushrooms in nature

Many mushrooms grow together with the roots of trees and grasses. Their cooperation is mutually beneficial. Plants give sugar and proteins to fungi, and fungi destroy dead plant remains in the soil and absorb water with mineral substances dissolved in it with the entire surface of the hyphae. Roots fused with fungi are called mycorrhiza. Most trees and grasses form mycorrhiza.

Fungi play the role of destroyers in ecosystems. They destroy dead wood and leaves, plant roots and animal carcasses. They turn all dead remains into carbon dioxide, water and mineral salts - into what plants can absorb. When fed, mushrooms gain weight and become food for animals and other fungi.

Mushrooms belonged to lower plants until the end of the 20th century. In 1970, they were finally separated into a separate kingdom of Mushrooms, because. have a number of features that distinguish them from plants and bring them closer to animals.

general characteristics

Kingdom mushrooms are unicellular and multicellular organisms. At present, taxonomists have counted more than 100 thousand species of fungi.

Fungi are heterotrophic organisms that do not have chlorophyll. They occupy an intermediate position between animals and plants, as they are characterized by a number of properties that bring them closer to animals and plants.

Common signs of fungi and animals:

• There is chitin in the cell membrane;
• as a reserve product, they accumulate glycogen, not starch;
• as a result of the exchange, urea is formed;
• lack of chloroplasts and photosynthetic pigments;

Common signs of fungi and plants:

• Unlimited growth;
• absorption nutrition, i.e. not swallowing food, but absorption;
• the presence of a pronounced cell wall;
• reproduction by spores;
• immobility;
• ability to synthesize vitamins.

Mushroom nutrition

Many species of the fungi kingdom live in cohabitation (symbiosis) with algae and with higher plants. Mutually beneficial cohabitation of fungal mycelium with the roots of higher plants forms mycorrhiza (for example, boletus with birch, boletus with aspen).

Many higher plants (trees, durum wheat, etc.) cannot grow normally without mycorrhiza. Fungi receive oxygen, root secretions, and nitrogen-free compounds from higher plants. Mushrooms “help” higher plants to assimilate hard-to-reach substances from humus by activating the activity of enzymes of higher plants, promote carbohydrate metabolism, fix free nitrogen, which is used by higher plants in a number of compounds, give them growth substances, vitamins, etc.

The Kingdom of Mushrooms is conditionally divided into lower and higher. The basis of the vegetative body of fungi is the mycelium, or mycelium. Mycelium consists of thin threads, or hyphae, similar to fluff. These threads are inside the substrate on which the fungus lives.

Most often, the mycelium occupies a large surface. Through mycelium nutrients are absorbed by osmosis. The mycelium of lower fungi either divides into cells, or there are no intercellular partitions.

Uninuclear or multinucleated fungal cells are in most cases covered with a thin cell membrane. Under it is the cytoplasmic membrane, enveloping the cytoplasm.

In the cell of fungi there are enzymes, proteins and such organelles (lysosomes) in which proteins are broken down by proteolytic enzymes. Mitochondria are similar to those in higher plants. Vacuoles contain reserve nutrients: glycogen, lipids, fatty acids, fats, etc.

Edible mushrooms contain many vitamins and mineral salts. Approximately 50% of the dry mass of mushrooms are nitrogenous substances, of which about 30% are proteins.

Fungi reproduce asexually:

• Specialized cells - spores;
• vegetatively - parts of the mycelium, budding.

The process of sporulation may be preceded by the sexual process, which is very diverse in fungi. A zygote can be formed as a result of the fusion of somatic cells specialized in gametes and germ cells - gametes (formed in the genital organs - gametangia). The resulting zygote germinates immediately or after a dormant period and gives rise to hyphae with organs of sexual sporulation, in which spores are formed.

Spores of various fungi are spread by insects, various animals, humans and air currents.

The value of mushrooms in nature and human life

Molds settle on food, in the soil, on vegetables and fruits. They cause spoilage of benign products (bread, vegetables, berries, fruits, etc.). Most of these fungi are saprophytes. However, some mold fungi are the causative agents of contagious diseases of humans, animals and plants. For example, the Trichophyton fungus causes ringworm in humans and animals.

Everyone is well aware of the unicellular fungus mukor, or white mold, which settles on vegetables, bread and horse manure. Initially, white mold has a fluffy coating, and over time it turns black, as rounded heads (sporangia) are formed on the mycelium, in which a huge number of dark-colored spores are formed.

Antibiotics are obtained from a number of mold genera (penicillin, aspergillus).

Under natural conditions, yeast is usually located on the surface of vegetables, fruits, in flower nectar and in stale foliage. Also, yeast is often found in the intestinal environment of many animals and humans.

Yeast composition

The cell consists of ¾ water, about half of it binds organelles, and ¼ is the liberated part. Based on age and general condition, we can indicate the approximate composition of dry cell matter:

• Nitrogen - 43-60%;
• Sugar - 16-39%;
• Fat - 2-14%;
• Minerals - 6-12%.

In addition to the main components, the cell also contains the content of important elements for metabolism - vitamins and enzymes.

Cell structure

The shape of the cell is varied, it can be spherical, elliptical or rod-shaped. Dimensions depend on the habitat and its conditions. Characteristics of yeast produced by the properties of younger yeast.

Yeast cells are composed of the following components:

• Cytoplasm;
• Core;
• Membrane;
• Mitochondria;
• Glycogen;
• Golgi apparatus;
• Ribosomes.

Breath

Oxygen is vital for the respiratory activity of yeast cells. But if necessary, yeast can completely do without it for some time.

Yeast Nutrition

Most of the species for energy in the process of nutrition use components of organic origin. In the absence of oxygen in the medium, yeast cells more often use various carbohydrates. In an environment enriched with oxygen, more types of substances are available for synthesis.

Yeast waste products

Yeast cells in the process of synthesis produce several types of alcohols, as well as various fatty acids. In addition, yeast cells have the ability to release certain substances into the environment, such as aldehydes and fusel oils.

reproduction

Yeast cells usually reproduce vegetatively by budding or division. There are known cases of sexual reproduction in some yeasts. In addition, there are yeast cells that form mycelium, which subsequently breaks up into individual arthrospores.

Yeast cell growth

Yeast growth is determined by the influence of environmental factors - temperature and humidity, acidity and atmospheric pressure. Favorable for enhanced growth is the average temperature.

Benefits of Yeast Organisms

Yeast is widely used not only in the food industry, in the production of bakery products and drinks, but also in the production of many useful elements - vitamins, polysaccharides, organic acids, enzymes and carotenoids.

The use of yeast cells in pharmacology and medicine

Biotechnologists use yeast cells in the production of many drugs. It is useful to use brewer's yeast in the treatment and prevention of allergic reactions. Cosmetologists recommend using them to strengthen general condition body and skin.

There is also a type of yeast that normalizes the functioning of the intestines and restores the microflora of the stomach. These yeast organisms help fight diarrhea and irritable bowels.