Every bacterium. Bacteria, their structure and vital activity - Knowledge Hypermarket. Varieties of beneficial bacteria

Bacteria is the most ancient organism on earth, as well as the simplest in its structure. It consists of only one cell, which can only be seen and studied under a microscope. characteristic feature bacteria is the absence of a nucleus, which is why bacteria are classified as prokaryotes.

Some species form small groups cells, such clusters can be surrounded by a capsule (sheath). The size, shape, and color of bacteria are highly dependent on the environment.

In terms of shape, bacteria are divided into: rod-shaped (bacilli), spherical (cocci) and convoluted (spirilla). There are also modified ones - cubic, C-shaped, star-shaped. Their sizes range from 1 to 10 microns. Certain types of bacteria can actively move with the help of flagella. The latter sometimes exceed the size of the bacterium itself twice.

Types of bacteria forms

For movement, bacteria use flagella, the number of which is different - one, a pair, a bundle of flagella. The location of the flagella is also different - on one side of the cell, on the sides, or evenly distributed over the entire plane. Also, one of the ways of movement is considered to be sliding due to the mucus that the prokaryote is covered with. Most have vacuoles inside the cytoplasm. Adjusting the capacity of the gas in the vacuoles helps them move up or down in the liquid, as well as move through the air channels of the soil.

Scientists have discovered more than 10 thousand varieties of bacteria, but according to the assumptions of scientific researchers, there are more than a million species of them in the world. general characteristics bacteria makes it possible to determine their role in the biosphere, as well as to study the structure, types and classification of the kingdom of bacteria.

habitats

The simplicity of the structure and the speed of adaptation to environmental conditions helped bacteria to spread over a wide range of our planet. They exist everywhere: water, soil, air, living organisms - all this is the most acceptable habitat for prokaryotes.

Bacteria have been found both at the south pole and in geysers. They are on the ocean floor, as well as in the upper layers of the Earth's air shell. Bacteria live everywhere, but their number depends on favorable conditions. For example, a large number of bacterial species live in open water bodies, as well as in the soil.

Structural features

A bacterial cell is distinguished not only by the fact that it does not have a nucleus, but also by the absence of mitochondria and plastids. The DNA of this prokaryote is located in a special nuclear zone and has the form of a nucleoid closed in a ring. In bacteria, the cell structure consists of a cell wall, a capsule, a capsule-like membrane, flagella, pili, and a cytoplasmic membrane. Internal structure make out the cytoplasm, granules, mesosomes, ribosomes, plasmids, inclusions and nucleoid.

The bacterial cell wall performs the function of defense and support. Substances can freely flow through it due to permeability. This shell contains pectin and hemicellulose. Some bacteria secrete a special mucus that can help protect against drying out. Mucus forms a capsule - a polysaccharide along chemical composition. In this form, the bacterium is able to tolerate even very high temperatures. It also performs other functions, for example, sticking to any surfaces.

On the surface of the bacterial cell are thin protein villi - pili. There may be a large number of them. Pili help the cell to transfer genetic material, and also provide adhesion to other cells.

Under the plane of the wall is a three-layer cytoplasmic membrane. It guarantees the transport of substances, and also plays a significant role in the formation of spores.

The cytoplasm of bacteria is 75 percent made from water. The composition of the cytoplasm:

fishsomes;
mesosomes;
amino acids;
enzymes;
pigments;
sugar;
granules and inclusions;
nucleoid.

Metabolism in prokaryotes is possible, both with the participation of oxygen and without it. Most of them feed on ready-made nutrients of organic origin. Very few species are able to synthesize themselves organic matter from inorganic. These are blue-green bacteria and cyanobacteria, which played a significant role in shaping the atmosphere and saturating it with oxygen.

reproduction

In conditions favorable for reproduction, it is carried out by budding or vegetatively. Asexual reproduction occurs in the following sequence:

The bacterial cell reaches its maximum volume and contains the necessary supply of nutrients.
The cell lengthens, a partition appears in the middle.
Within the cell, a division of the nucleotide occurs.
DNA main and separated diverge.
The cell is divided in half.
Residual formation of daughter cells.

With this method of reproduction, there is no exchange of genetic information, so all daughter cells will be an exact copy of the mother.

The process of reproduction of bacteria in adverse conditions is more interesting. Scientists learned about the ability of bacteria to reproduce sexually relatively recently - in 1946. Bacteria do not have a division into female and germ cells. But they have different DNA. Two such cells, when approaching each other, form a channel for the transfer of DNA, an exchange of sites occurs - recombination. The process is quite long, the result of which are two completely new individuals.

Most bacteria are very difficult to see under a microscope because they do not have their own color. Few varieties are purple or green due to their content of bacteriochlorophyll and bacteriopurpurine. Although if we consider some colonies of bacteria, it becomes clear that they release colored substances into the environment and acquire a bright color. In order to study prokaryotes in more detail, they are stained.

Classification

The classification of bacteria can be based on indicators such as:

The form
way to travel;
way to get energy;
waste products;
degree of danger.

Bacteria symbionts live in partnership with other organisms.

Bacteria saprophytes live on already dead organisms, products and organic waste. They contribute to the processes of decay and fermentation.

Decay cleanses nature of corpses and other wastes of organic origin. Without the process of decay, there would be no cycle of substances in nature. So what is the role of bacteria in the cycling of matter?

Decay bacteria are an assistant in the process of breaking down protein compounds, as well as fats and other compounds containing nitrogen. After a difficult chemical reaction, they break the bonds between the molecules of organic organisms and capture the molecules of protein, amino acids. Splitting, the molecules release ammonia, hydrogen sulfide and other harmful substances. They are poisonous and can cause poisoning in humans and animals.

Decay bacteria multiply rapidly in favorable conditions for them. Since these are not only beneficial bacteria, but also harmful ones, in order to prevent premature decay in products, people have learned to process them: dry, pickle, salt, smoke. All of these treatments kill bacteria and prevent them from multiplying.

Fermentation bacteria with the help of enzymes are able to break down carbohydrates. People noticed this ability in ancient times and use such bacteria to make lactic acid products, vinegars, and other food products to this day.

Bacteria, working in conjunction with other organisms, do very important chemical work. It is very important to know what types of bacteria are and what benefits or harm they bring to nature.

Significance in nature and for man

It has already been noted above great importance many types of bacteria (during decay processes and various types of fermentation), i.e. fulfillment of a sanitary role on Earth.

Bacteria also play a huge role in the cycle of carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, calcium and other elements. Many types of bacteria contribute to the active fixation of atmospheric nitrogen and convert it into an organic form, contributing to an increase in soil fertility. Of particular importance are those bacteria that decompose cellulose, which are the main source of carbon for the vital activity of soil microorganisms.

Sulfate-reducing bacteria are involved in the formation of oil and hydrogen sulfide in therapeutic mud, soils and seas. Thus, the layer of water saturated with hydrogen sulfide in the Black Sea is the result of the vital activity of sulfate-reducing bacteria. The activity of these bacteria in soils leads to the formation of soda and soda salinization of the soil. Sulfate-reducing bacteria convert nutrients in rice plantation soils into a form that becomes available to the roots of the crop. These bacteria can cause corrosion of metal underground and underwater structures.

Thanks to the vital activity of bacteria, the soil is freed from many products and harmful organisms and saturated with valuable nutrients. Bactericidal preparations are successfully used to combat many types of insect pests (corn borer, etc.).

Many types of bacteria are used in various industries to produce acetone, ethyl and butyl alcohols, acetic acid, enzymes, hormones, vitamins, antibiotics, protein and vitamin preparations, etc.

Without bacteria, processes are impossible in tanning leather, drying tobacco leaves, making silk, rubber, processing cocoa, coffee, urinating hemp, flax and other bast-fiber plants, sauerkraut, sewage treatment, leaching metals, etc.

The totality of bacteria that inhabit the human body has a common name - the microbiota. In a normal, healthy human microflora, there are several million bacteria. Each of them plays important role for the normal functioning of the human body.

In the absence of any type of beneficial bacteria, a person begins to get sick, the work of the gastrointestinal tract and respiratory tract is disrupted. Beneficial bacteria for humans are concentrated on the skin, in the intestines, on the mucous membranes of the body. The number of microorganisms is regulated by the immune system.

Normally, the human body contains both beneficial and pathogenic microflora. Bacteria can be beneficial or pathogenic.

There are many more beneficial bacteria. They make up 99% of total number microorganisms.

In this position, the necessary balance is maintained.

Among the different types of bacteria that live on the human body, we can distinguish:

bifidobacteria;
lactobacilli;
enterococci;
coli.

bifidobacteria

This type of microorganisms is the most common, involved in the production of lactic acid and acetate. It creates an acidic environment, thereby neutralizing most pathogenic microbes. Pathogenic flora ceases to develop and cause the processes of decay and fermentation.

Bifidobacteria play an important role in the life of a child, as they are responsible for the presence of an allergic reaction to any food. In addition, they have an antioxidant effect, prevent the development of tumors.

The synthesis of vitamin C is not complete without the participation of bifidobacteria. In addition, there is information that bifidobacteria help to absorb vitamins D and B, which are necessary for a person for normal life. In the presence of a deficiency of bifidobacteria, even taking synthetic vitamins of this group will not bring any result.

lactobacilli

This group of microorganisms is also important for human health. Due to their interaction with other inhabitants of the intestine, the growth and development of pathogenic microorganisms is blocked, pathogens of intestinal infections are suppressed.

Lactobacilli are involved in the formation of lactic acid, lysocin, bacteriocins. This is a great help to the immune system. If there is a deficiency of these bacteria in the intestine, then dysbacteriosis develops very quickly.

Lactobacilli colonize not only the intestines, but also the mucous membranes. So these microorganisms are important for women's health. They maintain the acidity of the vaginal environment, do not allow the development of bacterial vaginosis.

coli

Not all types of E. coli are pathogenic. Most of them, on the contrary, perform a protective function. The usefulness of the genus Escherichia coli lies in the synthesis of cocilin, which actively resists the bulk of pathogenic microflora.

These bacteria are useful for the synthesis of various groups of vitamins, folic and nicotinic acid. Their role in health should not be underestimated. For example, folic acid is essential for the production of red blood cells and the maintenance of normal hemoglobin levels.

Enterococci

This type of microorganism colonizes the human intestine immediately after birth.

They help digest sucrose. Living mainly in the small intestine, they, like other beneficial non-pathogenic bacteria, provide protection against excessive reproduction of harmful elements. At the same time, enterococci are conditionally safe bacteria.

If they begin to exceed the permissible norms, various bacterial diseases develop. The list of diseases is very large. Ranging from intestinal infections, ending with meningococcal.

The positive effect of bacteria on the body

Beneficial features non-pathogenic bacteria are very diverse. As long as there is a balance between the inhabitants of the intestines and mucous membranes, the human body functions normally.

Most bacteria are involved in the synthesis and breakdown of vitamins. Without their presence, B vitamins are not absorbed by the intestines, which leads to disorders nervous system, skin diseases, lowering hemoglobin.

The bulk of undigested food components that have reached the large intestine are broken down precisely due to bacteria. In addition, microorganisms ensure the constancy of water-salt metabolism. More than half of the entire microflora is involved in the regulation of the absorption of fatty acids and hormones.

The intestinal microflora forms local immunity. It is here that the destruction of the bulk of pathogenic organisms takes place, the harmful microbe is blocked.

Accordingly, people do not feel bloating and flatulence. An increase in lymphocytes provokes active phagocytes to fight the enemy, stimulate the production of immunoglobulin A.

Useful non-pathogenic microorganisms have a positive effect on the walls of the small and large intestines. They maintain a constant level of acidity there, stimulate the lymphoid apparatus, the epithelium becomes resistant to various carcinogens.

Intestinal peristalsis also largely depends on what microorganisms are in it. Suppression of the processes of decay and fermentation is one of the main tasks of bifidobacteria. Many microorganisms long years develop in symbiosis with pathogenic bacteria, thereby controlling them.

Biochemical reactions that constantly occur with bacteria release a lot of heat energy, maintaining the overall heat balance of the body. Microorganisms feed on undigested residues.

Dysbacteriosis

Dysbacteriosis is a change in the quantitative and qualitative composition of bacteria in the human body . In this case, beneficial organisms die, and harmful organisms actively multiply.

Dysbacteriosis affects not only the intestines, but also the mucous membranes (there may be dysbacteriosis oral cavity, vagina). In the analyzes, the names will prevail: streptococcus, staphylococcus, micrococcus.

In the normal state, beneficial bacteria regulate the development of pathogenic microflora. Skin, respiratory organs are usually under reliable protection. When the balance is disturbed, a person feels the following symptoms: intestinal flatulence, bloating, abdominal pain, upset.

Later, weight loss, anemia, vitamin deficiency may begin. From the reproductive system, abundant discharge is observed, often accompanied by an unpleasant odor. Irritations, roughness, cracks appear on the skin. Dysbacteriosis is a side effect after taking antibiotics.

If you find such symptoms, you should definitely consult a doctor who will prescribe a set of measures to restore normal microflora. This often requires taking probiotics.

>>Bacteria, their structure and activity

1 - mold fungus; 1 - lines; 3, 4 - scale lichens; $ - parmelia on a birch trunk; 6 - sulfur yellow tinder fungus

§ 92. Bacteria, their structure and vital activity

There is practically no place on Earth where bacteria are not found.. There are especially many bacteria in soil . 1 gram of soil can contain hundreds of millions of bacteria. The number of bacteria is different in the air of ventilated and unventilated rooms. So, in classrooms, after ventilation before the start of the lesson, bacteria are 13 times less than in the same rooms after lessons. There are few bacteria in the air high in the mountains, but the air in the streets of large cities contains many bacteria.

To get acquainted with the structural features of bacteria, consider a micropreparation of hay bacillus. Each such bacterium is only one rod-shaped cell with a thin membrane and cytoplasm . There is no typical nucleus in the cytoplasm. nuclear substance in most bacteria it is scattered in the cytoplasm. The structure of other bacteria is similar to the structure of hay bacillus.

The vast majority of bacteria are colorless. Only a few are colored purple or green color. The shape of bacteria is different. There are bacteria in the form of balls; there are rod-shaped forms of bacteria - hay sticks also belong to them; there are bacteria curved and similar to spirals 185.

Some bacteria have flagella that help them move. Many bacteria join in chains, or groups, forming huge accumulations in the form of films. Some bacteria can form spores. At the same time, the content cells , shrinking, moves away from the shell, rounds off and forms on its surface, being inside the parent shell, a new, denser shell. Such a bacterial cell is called a spore. Spores persist for a very long time in the most unfavorable conditions. They withstand drying, heat and frost, do not die immediately even in boiling water. Spores are easily carried by wind, water, stick to objects. There are many of them in the air and soil. Under favorable conditions, the spore germinates and becomes a viable bacterium. Bacterial spores are adaptations for bacterial survival in adverse conditions.

Bacteria live in a variety of conditions.. Some of them live and reproduce only with access to air, others do not need it. Most types of bacteria feed on ready-made organic substances, since they do not have chlorophyll. Only a very few are able to create organic substances from inorganic ones. These are blue-green, or cyanobacteria. They played an important role in the accumulation of oxygen in the Earth's atmosphere (see p. 225).

Once in conditions favorable for development, the bacterium divides, forming two daughter cells; in some bacteria, divisions are repeated every 20 minutes and more and more new generations of bacteria appear. To destroy bacteria and their spores, they are exposed to steam at a temperature of 120 ° C for 20 minutes.

To culture hay bacillus, place some hay in a flask of water, cover the neck of the flask with cotton wool, and boil the contents for 30 minutes to kill any other bacteria that may be in the flask. The hay stick will not die when boiled.

Filter the resulting infusion of hay and put it in a room with a temperature of 20-25 degrees Celsius for several days. The hay bacillus will multiply, and soon the surface of the water will be covered with a film of bacteria.

Korchagina V.A., Biology: Plants, bacteria, fungi, lichens: Proc. for 6 cells. avg. school - 24th ed. - M.: Enlightenment, 2003. - 256 p.: ill.

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A new study reveals a surprising fact about the numerous types of gut bacteria that can generate electricity. Electrogenic bacteria are bacteria that are capable of producing a certain amount of electricity. The researchers, led by Professor Dan Portnoy, published their discovery in the journal Nature.

bacteria and electricity

Until now, electrogenic bacteria have been found in rather specific natural environments, such as sediments from various water bodies. These environments are usually anaerobic - do not contain free oxygen. For the first time, researchers at the University of California at Berkeley have found that hundreds of different bacteria in the human gut are also electrogenic. These include many types of bacteria, from pathogens that can cause disease to probiotics that promote gut health. However, these gut bacteria produce electricity using a different mechanism.

Pathogens that generate electricity

Scientists have identified electricity-generating bacteria that include Listeria monocytogenes (a common culprit in diarrhea), Clostridium perfringens (causes gangrene), and Enterococcus faecalis (a pathogen acquired during a hospital stay). However, many other electricity-producing bacteria in the gut are not pathogens. Some of them are probiotics.

"The fact that so many of the bacteria that interact with humans, either as pathogens or being probiotics or involved in fermentation, are electrogenic has been missed before," the study author says. "This can tell us a lot about how these bacteria infect us or help us have a healthy gut."

What will this discovery give us?

The scientists expect that their unexpected finding could also be useful in future projects aimed at creating microbes. fuel cells, an innovative strategy for the production of renewable energy.

The researchers explain that bacteria generate electricity as part of their metabolism, a process they liken to respiration. However, while organisms such as plants and animals that live in oxygen-rich environments use oxygen to help them metabolize, bacteria that live in anaerobic environments must use other chemical elements. For example, bacteria that live on the bottom of lakes typically use minerals such as iron or manganese during their complex metabolic process, thereby generating electricity. However, the electrogenic bacteria that live in the intestines have a simpler process of generating electricity, and they use organic compound, known as a flavin, which is a derivative of vitamin B2.

"It appears that the cellular structure of these bacteria and the vitamin-rich ecological niche they occupy make it much easier and more cost-effective to move electrons out of the cell," explains Sam Light, author of the first study. How much energy do intestinal bacteria produce?

The researchers ran additional tests to see how much electricity these gut bacteria can generate. They found that gut bacteria generate almost as much electricity as other electrogenic bacteria: up to 100,000 electrons per second per cell.

In particular, scientists were surprised to find that lactobacillus, which plays a role in fermentation and is used to make cheese, yogurt, and sauerkraut, also has electrogenic properties.

Now scientists are wondering if these properties have anything to do with the taste that lactobacillus creates in food products obtained by fermentation.

"It's a whole lot of bacterial physiology that people didn't know existed and could be manipulated," Light concludes.