Beneficial and harmful bacteria. What bacteria are the most dangerous to humans

Many types of bacteria are useful and successfully used by humans.

Firstly, beneficial bacteria are widely used in the food industry.

In the production of cheeses, kefir, cream, milk coagulation is necessary, which occurs under the action of lactic acid. Lactic acid is produced by lactic acid bacteria, which are part of the starter cultures and feed on the sugar contained in milk. Lactic acid itself promotes the absorption of iron, calcium, phosphorus. These useful elements help us to overcome infectious diseases.

In the production of cheese, it is pressed into pieces (heads). The cheese heads are sent to the ripening chambers, where the activity of various lactic and propionic acid bacteria included in its composition begins. As a result of their activity, the cheese "ripens" - it acquires a characteristic taste, smell, pattern and color.

For the production of kefir, a starter containing lactic acid bacilli and lactic acid streptococci is used.

Yogurt is a tasty and healthy fermented milk product. Milk for the production of yogurt must be of very high quality. It should have a minimum amount of harmful bacteria that can interfere with the development of beneficial yogurt bacteria. Yoghurt bacteria convert milk into yogurt and give it a distinctive flavor.

Rice. 14. Lactobacilli - lactic acid bacteria.

Lactic acid and yogurt bacteria entering the human body with food help to fight not only harmful bacteria in the intestines, but also viruses that cause colds and other infections. In the course of their life activity, these beneficial bacteria create such an acidic environment (due to the excreted metabolic products) that only a microbe very adapted to harsh conditions, such as E. coli, can survive next to them.

The activity of beneficial bacteria is used in the fermentation of cabbage and other vegetables.

Secondly, bacteria are used to leach ores in the extraction of copper, zinc, nickel, uranium and other metals from natural ores. Leaching is the extraction of minerals from ore that is not rich in them with the help of bacteria, when other methods of obtaining (for example, smelting the ore) are inefficient and expensive. Leaching is carried out by aerobic bacteria.

Thirdly, beneficial aerobic bacteria are used to clean wastewater from cities and industrial enterprises from organic remains.

The main purpose of such biological treatment is the neutralization of complex and insoluble organic substances of wastewater that cannot be extracted from it by mechanical treatment, and their decomposition into simple water-soluble elements.

Fourth, bacteria are used in the production of silk and leather processing, etc. Raw materials for the manufacture of artificial silk are produced by special transgenic bacteria. Technical lactic acid bacteria are used in the leather industry for swelling and deashing (treatment of raw materials from solid compounds), in the textile industry, as an auxiliary agent for dyeing and printing.

Fifth, bacteria are used to control agricultural pests. Agricultural plants are treated with special preparations that contain certain types of bacteria. Insects - pests, absorbing parts of plants treated with biological products, swallow bacterial spores with food. This leads to the death of pests.

sixth, bacteria are used to produce various medicines (for example, interferon) that kill viruses and support human immunity (protection).

And the last, harmful bacteria also have beneficial properties.

Decay bacteria (coprophytic bacteria) destroy the corpses of dead animals, leaves of trees and shrubs that have fallen to the ground, and the trunks of dead trees themselves. These bacteria are a kind of orderlies of our planet. They feed on organic matter and turn it into humus - a fertile layer of the earth.

Soil bacteria live in the soil and also provide many benefits in nature. Mineral salts, which are produced by soil bacteria, are then absorbed from the soil by plant roots. One cubic centimeter of the surface layer of forest soil contains hundreds of millions of soil bacteria.

Rice. 15. Clostridia - soil bacteria.

Bacteria also live in the soil, which absorb nitrogen from the air, accumulating it in their body. This nitrogen is then converted into proteins. After the death of bacterial cells, these proteins turn into nitrogenous compounds (nitrates), which are fertilizer and are well absorbed by plants.

Conclusion.

Bacteria are a large, well-studied group of microorganisms. Bacteria are found everywhere and a person meets with them in his life all the time. Bacteria can be beneficial to humans, and can become a source of dangerous diseases.

The study of the properties of bacteria, the fight against their harmful manifestations and the use of the beneficial properties of the vital activity of bacteria is one of the main tasks for humans.

6th grade student B _________________________________ / Yaroslav Shchipanov /

Literature.

1. Berkinblit M.B., Glagolev S.M., Maleeva Yu.V., Biology: Textbook for grade 6. – M.: Binom. Knowledge Lab, 2008.

2. Ivchenko, T. V. Electronic textbook “Biology: Grade 6. Living organism". // Biology at school. - 2007.

3. Pasechnik V.V. Biology. 6 cells Bacteria, fungi, plants: Proc. for general education textbook establishments, - 4th ed., stereotype. – M.: Bustard, 2000.

4. Smelova, V.G. Digital microscope at biology lessons // Publishing House "First of September" Biology. - 2012. - No. 1.

Bacteria are the most ancient group of organisms that currently exist on Earth. The first bacteria probably appeared more than 3.5 billion years ago and for almost a billion years were the only living creatures on our planet. Since these were the first representatives of wildlife, their body had a primitive structure.

Over time, their structure became more complex, but even today bacteria are considered the most primitive unicellular organisms. Interestingly, some bacteria still retain the primitive features of their ancient ancestors. This is observed in bacteria that live in hot sulfur springs and anoxic silts at the bottom of reservoirs.

Most bacteria are colorless. Only a few are colored purple or green. But the colonies of many bacteria have a bright color, which is due to the release of a colored substance into the environment or pigmentation of the cells.

The discoverer of the world of bacteria was Anthony Leeuwenhoek, a Dutch naturalist of the 17th century, who first created a perfect magnifying glass microscope that magnifies objects 160-270 times.

Bacteria are classified as prokaryotes and are separated into a separate kingdom - Bacteria.

body shape

Bacteria are numerous and diverse organisms. They differ in form.

bacterium name	Bacteria shape	Bacteria image
cocci		spherical
Bacillus		rod-shaped
Vibrio		curved comma
Spirillum		Spiral
streptococci		Chain of cocci
Staphylococci		Clusters of cocci
diplococci		Two round bacteria enclosed in one slimy capsule

Ways of transportation

Among bacteria there are mobile and immobile forms. The mobile ones move by means of wave-like contractions or with the help of flagella (twisted helical threads), which consist of a special flagellin protein. There may be one or more flagella. They are located in some bacteria at one end of the cell, in others - on two or over the entire surface.

But movement is also inherent in many other bacteria that do not have flagella. So, bacteria covered with mucus on the outside are capable of sliding movement.

Some water and soil bacteria without flagella have gas vacuoles in the cytoplasm. There can be 40-60 vacuoles in a cell. Each of them is filled with gas (presumably nitrogen). By regulating the amount of gas in vacuoles, aquatic bacteria can sink into the water column or rise to its surface, while soil bacteria can move in soil capillaries.

Habitat

Due to the simplicity of organization and unpretentiousness, bacteria are widely distributed in nature. Bacteria are found everywhere: in a drop of even the purest spring water, in grains of soil, in the air, on rocks, in polar snows, desert sands, on the ocean floor, in oil extracted from great depths, and even in hot spring water with a temperature of about 80ºС. They live on plants, fruits, in various animals and in humans in the intestines, mouth, limbs, and on the surface of the body.

Bacteria are the smallest and most numerous living things. Due to their small size, they easily penetrate into any cracks, crevices, pores. Very hardy and adapted to various conditions of existence. They tolerate drying, extreme cold, heating up to 90ºС, without losing viability.

There is practically no place on Earth where bacteria would not be found, but in different quantities. The living conditions of bacteria are varied. Some of them need air oxygen, others do not need it and are able to live in an oxygen-free environment.

In the air: bacteria rise to the upper atmosphere up to 30 km. and more.

Especially a lot of them in the soil. One gram of soil can contain hundreds of millions of bacteria.

In water: in the surface water layers of open reservoirs. Beneficial aquatic bacteria mineralize organic residues.

In living organisms: pathogenic bacteria enter the body from the external environment, but only under favorable conditions cause diseases. Symbiotic live in the digestive organs, helping to break down and assimilate food, synthesize vitamins.

External structure

The bacterial cell is dressed in a special dense shell - the cell wall, which performs protective and supporting functions, and also gives the bacterium a permanent, characteristic shape. The cell wall of a bacterium resembles the shell of a plant cell. It is permeable: through it, nutrients freely pass into the cell, and metabolic products go out into the environment. Bacteria often develop an additional protective layer of mucus, a capsule, over the cell wall. The thickness of the capsule can be many times greater than the diameter of the cell itself, but it can be very small. The capsule is not an obligatory part of the cell, it is formed depending on the conditions in which the bacteria enter. It keeps bacteria from drying out.

On the surface of some bacteria there are long flagella (one, two or many) or short thin villi. The length of the flagella can be many times greater than the size of the body of the bacterium. Bacteria move with the help of flagella and villi.

Internal structure

Inside the bacterial cell is a dense immobile cytoplasm. It has a layered structure, there are no vacuoles, so various proteins (enzymes) and reserve nutrients are located in the very substance of the cytoplasm. Bacterial cells do not have a nucleus. In the central part of their cells, a substance carrying hereditary information is concentrated. Bacteria, - nucleic acid - DNA. But this substance is not framed in the nucleus.

The internal organization of a bacterial cell is complex and has its own specific features. The cytoplasm is separated from the cell wall by the cytoplasmic membrane. In the cytoplasm, the main substance, or matrix, ribosomes and a small number of membrane structures that perform a variety of functions (analogues of mitochondria, endoplasmic reticulum, Golgi apparatus) are distinguished. The cytoplasm of bacterial cells often contains granules of various shapes and sizes. The granules may be composed of compounds that serve as a source of energy and carbon. Droplets of fat are also found in the bacterial cell.

In the central part of the cell, the nuclear substance, DNA, is localized, not separated from the cytoplasm by a membrane. This is an analogue of the nucleus - the nucleoid. Nucleoid does not have a membrane, nucleolus and a set of chromosomes.

Nutrition methods

Bacteria have different ways of feeding. Among them are autotrophs and heterotrophs. Autotrophs are organisms that can independently form organic substances for their nutrition.

Plants need nitrogen, but they themselves cannot absorb nitrogen from the air. Some bacteria combine nitrogen molecules in the air with other molecules, resulting in substances available to plants.

These bacteria settle in the cells of young roots, which leads to the formation of thickenings on the roots, called nodules. Such nodules are formed on the roots of plants of the legume family and some other plants.

The roots provide the bacteria with carbohydrates, and the bacteria give the roots nitrogen-containing substances that can be taken up by the plant. Their relationship is mutually beneficial.

Plant roots secrete many organic substances (sugars, amino acids, and others) that bacteria feed on. Therefore, especially many bacteria settle in the soil layer surrounding the roots. These bacteria convert dead plant residues into substances available to the plant. This layer of soil is called the rhizosphere.

There are several hypotheses about the penetration of nodule bacteria into root tissues:

• through damage to the epidermal and cortical tissue;
• through root hairs;
• only through the young cell membrane;
• due to companion bacteria producing pectinolytic enzymes;
• due to the stimulation of the synthesis of B-indoleacetic acid from tryptophan, which is always present in the root secretions of plants.

The process of introduction of nodule bacteria into the root tissue consists of two phases:

• infection of the root hairs;
• nodule formation process.

In most cases, the invading cell actively multiplies, forms the so-called infection threads, and already in the form of such threads moves into the plant tissues. Nodule bacteria that have emerged from the infection thread continue to multiply in the host tissue.

Filled with rapidly multiplying cells of nodule bacteria, plant cells begin to intensively divide. The connection of a young nodule with the root of a leguminous plant is carried out thanks to vascular-fibrous bundles. During the period of functioning, the nodules are usually dense. By the time of the manifestation of optimal activity, the nodules acquire a pink color (due to the legoglobin pigment). Only those bacteria that contain legoglobin are capable of fixing nitrogen.

Nodule bacteria create tens and hundreds of kilograms of nitrogen fertilizers per hectare of soil.

Metabolism

Bacteria differ from each other in metabolism. For some, it goes with the participation of oxygen, for others - without its participation.

Most bacteria feed on ready-made organic substances. Only a few of them (blue-green, or cyanobacteria) are able to create organic substances from inorganic ones. They played an important role in the accumulation of oxygen in the Earth's atmosphere.

Bacteria absorb substances from the outside, tear their molecules apart, assemble their shell from these parts and replenish their contents (this is how they grow), and throw out unnecessary molecules. The shell and membrane of the bacterium allows it to absorb only the right substances.

If the shell and membrane of the bacterium were completely impermeable, no substances would enter the cell. If they were permeable to all substances, the contents of the cell would mix with the medium - the solution in which the bacterium lives. For the survival of bacteria, a shell is needed that allows the necessary substances to pass through, but not those that are not needed.

The bacterium absorbs the nutrients that are near it. What happens next? If it can move independently (by moving the flagellum or pushing the mucus back), then it moves until it finds the necessary substances.

If it cannot move, then it waits until diffusion (the ability of the molecules of one substance to penetrate into the thick of the molecules of another substance) brings the necessary molecules to it.

Bacteria, together with other groups of microorganisms, perform a huge chemical job. By transforming various compounds, they receive the energy and nutrients necessary for their vital activity. Metabolic processes, ways of obtaining energy and the need for materials to build the substances of their body in bacteria are diverse.

Other bacteria satisfy all the needs for carbon necessary for the synthesis of organic substances of the body at the expense of inorganic compounds. They are called autotrophs. Autotrophic bacteria are able to synthesize organic substances from inorganic ones. Among them are distinguished:

Chemosynthesis

The use of radiant energy is the most important, but not the only way to create organic matter from carbon dioxide and water. Bacteria are known that use not sunlight as an energy source for such synthesis, but the energy of chemical bonds occurring in the cells of organisms during the oxidation of certain inorganic compounds - hydrogen sulfide, sulfur, ammonia, hydrogen, nitric acid, ferrous compounds of iron and manganese. They use the organic matter formed using this chemical energy to build the cells of their body. Therefore, this process is called chemosynthesis.

The most important group of chemosynthetic microorganisms are nitrifying bacteria. These bacteria live in the soil and carry out the oxidation of ammonia, formed during the decay of organic residues, to nitric acid. The latter, reacts with mineral compounds of the soil, turns into salts of nitric acid. This process takes place in two phases.

Iron bacteria convert ferrous iron to oxide. The formed iron hydroxide settles and forms the so-called swamp iron ore.

Some microorganisms exist due to the oxidation of molecular hydrogen, thereby providing an autotrophic way of nutrition.

A characteristic feature of hydrogen bacteria is the ability to switch to a heterotrophic lifestyle when provided with organic compounds and in the absence of hydrogen.

Thus, chemoautotrophs are typical autotrophs, since they independently synthesize the necessary organic compounds from inorganic substances, and do not take them ready-made from other organisms, like heterotrophs. Chemoautotrophic bacteria differ from phototrophic plants in their complete independence from light as an energy source.

bacterial photosynthesis

Some pigment-containing sulfur bacteria (purple, green), containing specific pigments - bacteriochlorophylls, are able to absorb solar energy, with the help of which hydrogen sulfide is split in their organisms and gives hydrogen atoms to restore the corresponding compounds. This process has much in common with photosynthesis and differs only in that in purple and green bacteria, hydrogen sulfide (occasionally carboxylic acids) is a hydrogen donor, and in green plants it is water. In those and others, the splitting and transfer of hydrogen is carried out due to the energy of absorbed solar rays.

Such bacterial photosynthesis, which occurs without the release of oxygen, is called photoreduction. The photoreduction of carbon dioxide is associated with the transfer of hydrogen not from water, but from hydrogen sulfide:

6CO 2 + 12H 2 S + hv → C6H 12 O 6 + 12S \u003d 6H 2 O

The biological significance of chemosynthesis and bacterial photosynthesis on a planetary scale is relatively small. Only chemosynthetic bacteria play a significant role in the sulfur cycle in nature. Absorbed by green plants in the form of salts of sulfuric acid, sulfur is restored and becomes part of protein molecules. Further, when dead plant and animal remains are destroyed by putrefactive bacteria, sulfur is released in the form of hydrogen sulfide, which is oxidized by sulfur bacteria to free sulfur (or sulfuric acid), which forms sulfites available for plants in the soil. Chemo- and photoautotrophic bacteria are essential in the cycle of nitrogen and sulfur.

sporulation

Spores form inside the bacterial cell. In the process of spore formation, a bacterial cell undergoes a series of biochemical processes. The amount of free water in it decreases, enzymatic activity decreases. This ensures the resistance of spores to adverse environmental conditions (high temperature, high salt concentration, drying, etc.). Spore formation is characteristic of only a small group of bacteria.

Spores are not an essential stage in the life cycle of bacteria. Sporulation begins only with a lack of nutrients or the accumulation of metabolic products. Bacteria in the form of spores can remain dormant for a long time. Bacterial spores withstand prolonged boiling and very long freezing. When favorable conditions occur, the dispute germinates and becomes viable. Bacterial spores are adaptations for survival in adverse conditions.

reproduction

Bacteria reproduce by dividing one cell into two. Having reached a certain size, the bacterium divides into two identical bacteria. Then each of them begins to feed, grows, divides, and so on.

After elongation of the cell, a transverse septum is gradually formed, and then the daughter cells diverge; in many bacteria, under certain conditions, cells after division remain connected in characteristic groups. In this case, depending on the direction of the division plane and the number of divisions, different forms arise. Reproduction by budding occurs in bacteria as an exception.

Under favorable conditions, cell division in many bacteria occurs every 20-30 minutes. With such rapid reproduction, the offspring of one bacterium in 5 days is able to form a mass that can fill all the seas and oceans. A simple calculation shows that 72 generations (720,000,000,000,000,000,000 cells) can be formed per day. If translated into weight - 4720 tons. However, this does not happen in nature, since most bacteria quickly die under the influence of sunlight, drying, lack of food, heating up to 65-100ºС, as a result of the struggle between species, etc.

The bacterium (1), having absorbed enough food, increases in size (2) and begins to prepare for reproduction (cell division). Its DNA (in a bacterium the DNA molecule is closed in a ring) doubles (the bacterium produces a copy of this molecule). Both DNA molecules (3.4) appear to be attached to the bacterial wall and, when elongated, the bacteria diverge to the sides (5.6). First, the nucleotide divides, then the cytoplasm.

After the divergence of two DNA molecules on bacteria, a constriction appears, which gradually divides the body of the bacterium into two parts, each of which contains a DNA molecule (7).

It happens (in hay bacillus), two bacteria stick together, and a bridge is formed between them (1,2).

DNA is transported from one bacterium to another via the jumper (3). Once in one bacterium, DNA molecules intertwine, stick together in some places (4), after which they exchange sections (5).

The role of bacteria in nature

Circulation

Bacteria are the most important link in the general circulation of substances in nature. Plants create complex organic substances from carbon dioxide, water and soil mineral salts. These substances return to the soil with dead fungi, plants and animal corpses. Bacteria decompose complex substances into simple ones, which are reused by plants.

Bacteria destroy the complex organic matter of dead plants and animal corpses, excretions of living organisms and various wastes. Feeding on these organic substances, saprophytic decay bacteria turn them into humus. These are the kind of orderlies of our planet. Thus, bacteria actively participate in the cycle of substances in nature.

soil formation

Since bacteria are distributed almost everywhere and are found in huge numbers, they largely determine the various processes that occur in nature. In autumn, the leaves of trees and shrubs fall, the above-ground grass shoots die off, old branches fall off, and from time to time the trunks of old trees fall. All this gradually turns into humus. In 1 cm 3. The surface layer of forest soil contains hundreds of millions of saprophytic soil bacteria of several species. These bacteria convert humus into various minerals that can be absorbed from the soil by plant roots.

Some soil bacteria are able to absorb nitrogen from the air, using it in life processes. These nitrogen-fixing bacteria live on their own or take up residence in the roots of leguminous plants. Having penetrated into the roots of legumes, these bacteria cause the growth of root cells and the formation of nodules on them.

These bacteria release nitrogen compounds that plants use. Bacteria obtain carbohydrates and mineral salts from plants. Thus, there is a close relationship between the leguminous plant and nodule bacteria, which is useful for both one and the other organism. This phenomenon is called symbiosis.

Thanks to their symbiosis with nodule bacteria, legumes enrich the soil with nitrogen, helping to increase yields.

Distribution in nature

Microorganisms are ubiquitous. The only exceptions are the craters of active volcanoes and small areas in the epicenters of detonated atomic bombs. Neither the low temperatures of the Antarctic, nor the boiling jets of geysers, nor saturated salt solutions in salt pools, nor the strong insolation of mountain peaks, nor the harsh radiation of nuclear reactors interfere with the existence and development of microflora. All living beings constantly interact with microorganisms, being often not only their storages, but also distributors. Microorganisms are the natives of our planet, actively developing the most incredible natural substrates.

Soil microflora

The number of bacteria in the soil is extremely large - hundreds of millions and billions of individuals in 1 gram. They are much more abundant in soil than in water and air. The total number of bacteria in soils varies. The number of bacteria depends on the type of soil, their condition, the depth of the layers.

On the surface of soil particles, microorganisms are located in small microcolonies (20-100 cells each). Often they develop in the thicknesses of clots of organic matter, on living and dying plant roots, in thin capillaries and inside lumps.

Soil microflora is very diverse. Different physiological groups of bacteria are found here: putrefactive, nitrifying, nitrogen-fixing, sulfur bacteria, etc. among them there are aerobes and anaerobes, spore and non-spore forms. Microflora is one of the factors of soil formation.

The area of ​​development of microorganisms in the soil is the zone adjacent to the roots of living plants. It is called the rhizosphere, and the totality of microorganisms contained in it is called the rhizosphere microflora.

Microflora of reservoirs

Water is a natural environment where microorganisms grow in large numbers. Most of them enter the water from the soil. A factor that determines the number of bacteria in water, the presence of nutrients in it. The cleanest are the waters of artesian wells and springs. Open reservoirs and rivers are very rich in bacteria. The greatest number of bacteria is found in the surface layers of water, closer to the shore. With increasing distance from the coast and increasing depth, the number of bacteria decreases.

Pure water contains 100-200 bacteria per 1 ml, while contaminated water contains 100-300 thousand or more. There are many bacteria in the bottom silt, especially in the surface layer, where the bacteria form a film. There are a lot of sulfur and iron bacteria in this film, which oxidize hydrogen sulfide to sulfuric acid and thereby prevent fish from dying. There are more spore-bearing forms in the silt, while non-spore-bearing forms predominate in the water.

In terms of species composition, the water microflora is similar to the soil microflora, but specific forms are also found. Destroying various wastes that have fallen into the water, microorganisms gradually carry out the so-called biological purification of water.

Air microflora

Air microflora is less numerous than soil and water microflora. Bacteria rise into the air with dust, can stay there for a while, and then settle to the surface of the earth and die from lack of nutrition or under the influence of ultraviolet rays. The number of microorganisms in the air depends on the geographic area, location, season, dust pollution, etc. Each speck of dust is a carrier of microorganisms. Most bacteria in the air over industrial enterprises. The air in the countryside is cleaner. The cleanest air is over forests, mountains, snowy spaces. The upper layers of the air contain fewer germs. In the air microflora there are many pigmented and spore-bearing bacteria that are more resistant than others to ultraviolet rays.

Microflora of the human body

The body of a person, even a completely healthy one, is always a carrier of microflora. When the human body comes into contact with air and soil, a variety of microorganisms, including pathogens (tetanus bacilli, gas gangrene, etc.), settle on clothing and skin. The exposed parts of the human body are most frequently contaminated. E. coli, staphylococci are found on the hands. There are over 100 types of microbes in the oral cavity. The mouth, with its temperature, humidity, nutrient residues, is an excellent environment for the development of microorganisms.

The stomach has an acidic reaction, so the bulk of microorganisms in it die. Starting from the small intestine, the reaction becomes alkaline, i.e. favorable for microbes. The microflora in the large intestine is very diverse. Each adult excretes about 18 billion bacteria daily with excrement, i.e. more individuals than people on the globe.

Internal organs that are not connected to the external environment (brain, heart, liver, bladder, etc.) are usually free from microbes. Microbes enter these organs only during illness.

Bacteria in the cycling

Microorganisms in general and bacteria in particular play an important role in the biologically important cycles of matter on Earth, carrying out chemical transformations that are completely inaccessible to either plants or animals. Various stages of the cycle of elements are carried out by organisms of different types. The existence of each separate group of organisms depends on the chemical transformation of elements carried out by other groups.

nitrogen cycle

The cyclic transformation of nitrogenous compounds plays a paramount role in supplying the necessary forms of nitrogen to various biosphere organisms in terms of nutritional needs. Over 90% of total nitrogen fixation is due to the metabolic activity of certain bacteria.

The carbon cycle

The biological transformation of organic carbon into carbon dioxide, accompanied by the reduction of molecular oxygen, requires the joint metabolic activity of various microorganisms. Many aerobic bacteria carry out the complete oxidation of organic substances. Under aerobic conditions, organic compounds are initially broken down by fermentation, and organic fermentation end products are further oxidized by anaerobic respiration if inorganic hydrogen acceptors (nitrate, sulfate, or CO2) are present.

Sulfur cycle

For living organisms, sulfur is available mainly in the form of soluble sulfates or reduced organic sulfur compounds.

The iron cycle

Some fresh water reservoirs contain high concentrations of reduced iron salts. In such places, a specific bacterial microflora develops - iron bacteria, which oxidize reduced iron. They participate in the formation of marsh iron ores and water sources rich in iron salts.

Bacteria are the most ancient organisms, appearing about 3.5 billion years ago in the Archaean. For about 2.5 billion years, they dominated the Earth, forming the biosphere, and participated in the formation of an oxygen atmosphere.

Bacteria are one of the most simply arranged living organisms (except for viruses). They are believed to be the first organisms to appear on Earth.

Bacteria are dangerous and useful, their role in human life

Bacterial infections are considered one of the most dangerous - humanity has been fighting pathogenic microorganisms for more than one century. However, not all bacteria are unambiguous enemies for humans. Many species are vital - they ensure proper digestion and even help the immune system defend itself against other microorganisms. MedAboutMe will tell you how to distinguish between bad and good bacteria, what to do if they are found in the analysis, and how to properly treat the diseases they cause.

Bacteria and man

It is believed that bacteria appeared on Earth more than 3.5 billion years ago. It was they who became active participants in creating suitable conditions for life on the planet, and throughout their existence they have been actively involved in important processes. For example, it is thanks to bacteria that the decay of the organic remains of animals and plants occurs. They also created fertile soil on Earth.

And since bacteria live literally everywhere, the human body is no exception. On the skin, mucous membranes, in the gastrointestinal tract, nasopharynx, urogenital tract, there are many microorganisms that interact with humans in different ways.

In the womb, the placenta protects the fetus from the penetration of bacteria, the population of the body occurs in the first days of life:

• The first bacteria the child receives, passing through the birth canal of the mother.
• Microorganisms enter the gastrointestinal tract through breastfeeding. Here, among more than 700 species, lactobacilli and bifidobacteria predominate (the benefits are described in the table of bacteria at the end of the article).
• The oral cavity is inhabited by staphylococci, streptococci and other microbes, which the child also receives with food and in contact with objects.
• On the skin, the microflora is formed from bacteria that predominate in the people around the child.

The role of bacteria for a person is invaluable, if already in the first months the microflora does not form normally, the child will lag behind in development and often get sick. After all, without symbiosis with bacteria, the body cannot function.

Beneficial and harmful bacteria

Everyone is well aware of the concept of dysbacteriosis - a condition in which the natural microflora in the human body is disturbed. Dysbacteriosis is a serious factor in lowering the immune defense, the development of various inflammations, disruption of the digestive tract and other things. The absence of beneficial bacteria contributes to the reproduction of pathogenic organisms, and fungal infections often develop against the background of dysbacteriosis.

At the same time, many pathogenic microbes live in the environment, which can cause serious illness. The most dangerous are those types of bacteria that in the process of life are capable of producing toxins (exotoxins). It is these substances that are today considered one of the most powerful poisons. Such microorganisms cause dangerous infections:

• Botulism.
• Gas gangrene.
• diphtheria.
• Tetanus.

In addition, the disease can also be provoked by bacteria that live in the human body under normal conditions, and when the immune system is weakened, they begin to become more active. The most popular pathogens of this kind are staphylococci and streptococci.

Bacteria life

Bacteria are full-fledged living organisms with a size of 0.5-5 microns, which are able to actively multiply in a suitable environment. Some of them need oxygen, others do not. There are motile and non-motile types of bacteria.

Bacteria cell

Most bacteria living on Earth are single-celled organisms. Mandatory components of any microbe:

• Nucleoid (nucleus-like region containing DNA).
• Ribosomes (carry out the synthesis of proteins).
• Cytoplasmic membrane (separates the cell from the external environment, maintains homeostasis).

Also, some bacterial cells have a thick cell wall, which additionally protects them from damage. Such organisms are more resistant to drugs and antigens that the human immune system produces.

There are bacteria with flagella (mototrichia, lophotrichia, peritrichia), due to which microorganisms are able to move. However, scientists have also recorded another type of movement characteristic of microbes - the sliding of bacteria. Moreover, recent studies show that it is inherent in those species that were previously considered immobile. For example, scientists from the University of Nottingham and Sheffield have shown that methicillin-resistant Staphylococcus aureus (one of the main representatives of the class of superbugs) is able to move without the help of flagella and villi. And this, in turn, significantly affects the understanding of the mechanisms of the spread of a dangerous infection.

Bacterial cells can be of the following forms:

• Round (cocci, from other Greek κόκκος - "grain").
• Rod-shaped (bacilli, clostridia).
• Sinuous (spirochetes, spirilla, vibrios).

Many microorganisms are able to stick together in colonies, so more often scientists and doctors isolate bacteria not by the structure of the element, but by the type of compounds:

• Diplococci are cocci connected in pairs.
• Streptococci are cocci that form chains.
• Staphylococci are cocci that form clusters.
• Streptobacteria are rod-shaped microorganisms connected in a chain.

Reproduction of bacteria

The vast majority of bacteria reproduce by division. The rate of spread of the colony depends on the external conditions and the type of microorganism itself. So, on average, one bacterium is able to divide every 20 minutes - it forms 72 generations of offspring per day. For 1-3 days, the number of descendants of one microorganism can reach several million. In this case, the reproduction of bacteria may not be so fast. For example, the process of division of Mycobacterium tuberculosis takes 14 hours.

If the bacteria enter a favorable environment and have no competitors, the population grows very quickly. Otherwise, its number is regulated by other microorganisms. That is why the human microflora is an essential factor in its protection against various infections.

bacterial spores

One of the features of rod-shaped bacteria is their ability to sporulate. These microorganisms are called bacilli, and they include such pathogenic bacteria:

• The genus Clostridium (cause gas gangrene, botulism, often cause complications during childbirth and after abortion).
• The genus Bacillus (cause anthrax, a number of food poisonings).

Bacterial spores are, in fact, a conserved cell of a microorganism that can survive for a long time without damage, and is practically not subject to various influences. In particular, spores are heat-resistant, not damaged by chemicals. Often the only possible effect is ultraviolet rays, under which the dried bacteria can die.

Bacterial spores form when the microorganism is exposed to unfavorable conditions. It takes approximately 18-20 hours to form inside the cell. At this time, the bacterium loses water, decreases in size, becomes lighter, and a dense shell forms under the outer membrane. In this form, the microorganism can freeze for hundreds of years.

When the spore of a bacterium is exposed to suitable conditions, it begins to germinate into a viable bacterium. The process takes about 4-6 hours.

Types of bacteria

According to the influence of bacteria on humans, they can be divided into three types:

• Pathogenic.
• Conditionally pathogenic.
• Non-pathogenic.

Beneficial bacteria

Non-pathogenic bacteria - those that never lead to disease, even if their numbers are large enough. Among the most famous species, lactic acid bacteria can be distinguished, which are actively used by humans in the food industry - for making cheeses, sour-milk products, dough and much more.

Another important species is bifidobacteria, which are the basis of the intestinal flora. In breastfed infants, they make up to 90% of all species living in the gastrointestinal tract. These bacteria for humans perform the following functions:

• Provide physiological protection of the intestine from the penetration of pathogenic organisms.
• They produce organic acids that prevent the reproduction of pathogenic microbes.
• They help to synthesize vitamins (K, group B), as well as proteins.
• Enhance the absorption of vitamin D.

The role of bacteria of this species is difficult to overestimate, because without them normal digestion is impossible, and hence the absorption of nutrients.

Opportunistic bacteria

As part of a healthy microflora, there are bacteria that are classified as opportunistic pathogens. These microorganisms can exist for years on the skin, in the nasopharynx or intestines of a person and not cause infections. However, under any favorable conditions (weakened immunity, microflora disturbances), their colony grows and becomes a real threat.

A classic example of an opportunistic bacterium is Staphylococcus aureus, a microbe that can cause over 100 different diseases, from boils on the skin to deadly blood poisoning (sepsis). At the same time, this bacterium is found in most people in various analyzes, but it still does not cause illness.

Among other representatives of the species of opportunistic microbes:

• Streptococci.
• Escherichia coli.
• Helicobacter pylori (capable of causing ulcers and gastritis, but lives in 90% of people as part of a healthy microflora).

Getting rid of these types of bacteria does not make sense, since they are widespread in the environment. The only adequate way to prevent infections is to strengthen the immune system and protect the body from dysbacteriosis.

Pathogenic bacteria behave differently - their presence in the body always means the development of an infection. Even a small colony can cause harm. Most of these microorganisms secrete two types of toxins:

• Endotoxins are poisons that are formed when cells are destroyed.
• Exotoxins are poisons that bacteria produce during their life. The most dangerous substances for humans that can lead to fatal intoxication.

The treatment of such infections is aimed not only at the destruction of pathogenic bacteria, but also at the removal of the poisoning caused by them. Moreover, in the case of infection with microbes such as tetanus bacillus, it is the introduction of toxoid that is the basis of therapy.

Other known pathogenic bacteria include:

• Salmonella.
• Pseudomonas aeruginosa.
• Gonococcus.
• Pale treponema.
• Shigella.
• Tuberculosis bacillus (Koch's stick).

Classes of bacteria

Today there are many classifications of bacteria. Scientists divide them according to the type of structure, ability to move and other features. However, the Gram classification and the type of breathing remain the most important.

Anaerobic and aerobic bacteria

Among the diversity of bacteria, two large classes are distinguished:

• Anaerobic - those that can do without oxygen.
• Aerobic - those that need oxygen to live.

A feature of anaerobic bacteria is their ability to live in environments where other microorganisms do not survive. The most dangerous in this regard are deep contaminated wounds, in which microbes develop rapidly. The characteristic signs of the growth of the population and life of bacteria in the human body are as follows:

• Progressive tissue necrosis.
• Subcutaneous suppurations.
• Abscesses.
• Internal lesions.

Anaerobes include pathogenic bacteria that cause tetanus, gas gangrene, and toxic lesions of the gastrointestinal tract. Also, the anaerobic class of bacteria includes many opportunistic microbes that live on the skin and in the intestinal tract. They become dangerous if they get into an open wound.

Disease-causing aerobic bacteria include:

• Tuberculosis bacillus.
• Vibrio cholerae.
• Tularemia stick.

The life of bacteria can proceed even with a small amount of oxygen. Such microbes are called facultative aerobic, salmonella and cocci (streptococcus, staphylococcus) are a striking example of the group.

In 1884, Danish physician Hans Gram discovered that different bacteria stained differently when exposed to methylene violet. Some retain color after washing, others lose it. Based on this, the following classes of bacteria were identified:

• Gram-negative (Gram-) - discoloring.
• Gram-positive (Gram +) - staining.

Staining with aniline dyes is a simple technique that makes it possible to quickly reveal the characteristics of the bacterial membrane wall. For those microbes that do not stain by Gram, it is more powerful and durable, which means that it is more difficult to deal with them. Gram-negative bacteria are primarily more resistant to antibodies produced by the human immune system. This class includes microbes that cause such diseases:

• Syphilis.
• Leptospirosis.
• Chlamydia.
• meningococcal infection.
• Hemophilus infection
• Brucellosis.
• Legionellosis.

The Gram+ class of bacteria includes the following microorganisms:

• Staphylococcus.
• Streptococcus.
• Clostridia (causative agents of botulism and tetanus).
• Listeria.
• Diphtheria stick.

Diagnosis of bacterial infections

Correct and timely diagnosis plays an important role in the treatment of bacterial infections. It is possible to accurately determine the disease only after the analysis, but it can already be suspected by the characteristic symptoms.

Bacteria and viruses: features of bacteria and differences in infections

Most often, a person is faced with acute respiratory diseases. As a rule, cough, rhinitis, fever and sore throat are caused by bacteria and viruses. And although at certain stages of the disease they can manifest themselves in the same way, their therapy will still be radically different.

Bacteria and viruses behave differently in the human body:

• Bacteria are full-fledged living organisms, large enough (up to 5 microns), capable of reproduction in a suitable environment (on mucous membranes, skin, in wounds). Pathogenic microbes secrete poisons that lead to intoxication. The same bacteria can cause infections of different localization. For example, Staphylococcus aureus affects the skin, mucous membranes, and can lead to blood poisoning.
• Viruses are non-cellular infectious agents that can reproduce only inside a living cell, and in the external environment do not manifest themselves as living organisms. At the same time, viruses are always highly specialized and can only infect a specific type of cell. For example, hepatitis viruses can only infect the liver. Viruses are much smaller than bacteria, their size does not exceed 300 nm.

Today, effective drugs have been developed against bacteria -. But these drugs do not act on viruses, moreover, according to the World Health Organization, antibacterial therapy for ARVI worsens the patient's condition.

Symptoms of bacterial infections

Most often, seasonal respiratory infections develop under the influence of bacteria and viruses according to the following scheme:

• The first 4-5 days manifest a viral infection.
• On the 4-5th day, if the rules for the treatment of acute respiratory viral infections were not followed, a bacterial lesion joins.

Symptoms of a bacterial infection in this case will be:

• Deterioration of the patient's condition after improvement.
• High temperature (38°C and above).
• Severe pain in the chest (a sign of the development of pneumonia).
• Discoloration of mucus - greenish, white or yellowish discharge from the nose and in expectorated sputum.
• Rash on the skin.

If it is possible to treat without the involvement of a doctor, since a viral infection resolves itself without complications in 4-7 days, then diseases caused by pathogenic bacteria must be consulted by a therapist or pediatrician.

Other bacterial infections are characterized by the following symptoms:

• General deterioration.
• A pronounced inflammatory process - pain in the affected area, hyperemia, fever.
• Suppuration.

Methods of transmission of bacterial infections

Harmful bacteria enter the human body in many ways. The most common ways of infection:

• Airborne.

Bacteria are found in the exhaled air, sputum of the patient, spread by coughing, sneezing and even talking. This route of transmission is typical for respiratory infections, in particular, whooping cough, diphtheria, scarlet fever.

• Contact household.

Microbes get to a person through dishes, door handles, furniture surfaces, towels, phones, toys and more. Also, live bacteria and bacterial spores can stay in the dust for a long time. This is how tuberculosis, diphtheria, dysentery, diseases caused by aureus and other types of staphylococcus aureus are transmitted.

• Alimentary (fecal-oral).

Bacteria enter the body through contaminated food or water. The transmission route is characteristic of gastrointestinal infections, in particular, typhoid fever, cholera, dysentery.

• Sexual.

Infection occurs during sexual intercourse, this is how STIs are transmitted, including syphilis and gonorrhea.

• Vertical.

The bacterium enters the fetus during pregnancy or childbirth. So the child can become infected with tuberculosis, syphilis, leptospirosis.

Deep wounds are dangerous for the development of infections - it is here that anaerobic bacteria, including tetanus bacillus, actively multiply. People with weakened immune systems are also more likely to contract a bacterial infection.

If you suspect the presence of pathogenic bacteria, the doctor may offer the following diagnostic options:

• Smear on flora.

If a respiratory infection is suspected, it is taken from the mucous membranes of the nose and throat. The analysis is also popular for detecting sexually transmitted infections. In this case, the material is taken from the vagina, visceral canal, urethra.

• Bacteriological culture.

It differs from a smear in that the taken biomaterial is not examined immediately, but is placed in an environment favorable for the reproduction of bacteria. After a few days or weeks, depending on the alleged pathogen, the result is evaluated - if there were harmful bacteria in the biomaterial, they grow into a colony. Bakposev is also good because during the analysis, not only the pathogen is determined, but also its quantity, as well as the sensitivity of the microbe to antibiotics.

• Blood test.

A bacterial infection can be detected by the presence of antibodies, antigens in the blood and by the leukocyte formula.

Today, biomaterial is often examined by PCR (polymerase chain reaction), in which infection can be detected even with a small number of microbes.

Positive test and bacterial infections

Since many bacteria are opportunistic and at the same time live in the body, on the mucous membranes and skin of the majority of the population, the results of the analysis must be able to correctly interpret. It must be remembered that the mere presence of bacteria in a person is not a sign of a bacterial infection and is not a reason to start treatment. For example, the norm for Staphylococcus aureus is 103–104. With these indicators, no therapy is required. Moreover, since the microflora of each person is individual, even if the values ​​\u200b\u200bare higher, but there will be no symptoms of the disease, the indicators can also be considered normal.

An analysis for different types of bacteria is prescribed if there are signs of infection:

• Feeling unwell.
• Purulent discharge.
• Inflammatory process.
• Greenish, white or yellow mucus from the nose and in the expectorated sputum.

A positive analysis for bacteria in the absence of symptoms is taken for control if microbes are detected in people from risk groups: pregnant women, children, people in the postoperative period, patients with reduced immunity and concomitant diseases. In this case, it is recommended to take several tests to see the growth dynamics of the colony. If the values ​​do not change, then the immune system is able to control the reproduction of bacteria.

Bacteria in the nasopharynx

Bacteria in the nasopharynx can cause respiratory tract infections. In particular, they are the cause of tonsillitis, bacterial tonsillitis and pharyngitis, as well as sinusitis. Running infections can cause a lot of inconvenience, chronic inflammation, persistent rhinitis, headaches and more. Such diseases are especially dangerous because harmful bacteria can descend through the respiratory tract and affect the lungs - causing pneumonia.

bacteria in urine

Ideally, it is urine that should be free from various microorganisms. The presence of bacteria in the urine may indicate an incorrectly passed analysis (in which microbes got into the material from the surface of the skin and mucous membranes), in which case the doctor asks to be examined again. If the result is confirmed, and the indicator exceeds 104 CFU / ml, bacteriuria (bacteria in the urine) indicates such diseases:

• Kidney damage, in particular, pyelonephritis.
• Cystitis.
• Urethritis.
• Inflammatory process in the urinary canal, for example, as a result of blocking it with a calculus. Observed in urolithiasis.
• Prostatitis or prostate adenoma.

In some cases, bacteria in the urine are found in diseases that are not associated with a local infection. A positive analysis can be with diabetes mellitus, as well as a generalized lesion - sepsis.

Normally, the gastrointestinal tract is inhabited by colonies of various bacteria. In particular, there are:

• Bifidobacteria.
• Lactic acid bacteria (lactobacilli).
• Enterococci.
• Clostridia.
• Streptococci.
• Staphylococci.
• Escherichia coli.

The role of the bacteria that make up the normal microflora is to protect the intestines from infections and ensure normal digestion. Therefore, often the biomaterial from the intestine is examined precisely because of the suspicion of dysbacteriosis, and not for the presence of pathogenic microorganisms.

However, some pathogenic bacteria can cause severe diseases, namely when they enter the gastrointestinal tract. Among these diseases:

• Salmonellosis.
• Cholera.
• Botulism.
• Dysentery.

bacteria on the skin

On the skin, as well as on the mucous membranes of the nasopharynx, in the intestines and genital organs, the balance of microflora is normally established. Bacteria live here - more than 100 species, among which epidermal and Staphylococcus aureus, streptococci are often found. With reduced immunity, and especially in children, they can provoke skin lesions, cause suppuration, boils and carbuncles, streptoderma, panaritium and other diseases.

In adolescence, the active reproduction of bacteria leads to acne and acne.

The main danger of microbes on the skin is the possibility of their entry into the bloodstream, wounds and other damage to the epidermis. In this case, harmless microorganisms on the skin can cause serious illness, even cause sepsis.

Diseases caused by bacteria

Bacteria are the cause of infections throughout the body. They affect the respiratory tract, cause inflammatory processes on the skin, cause diseases of the intestines and the genitourinary system.

Diseases of the respiratory tract and lungs

Angina

Angina is an acute lesion of the tonsils. The disease is typical for childhood.

Pathogen:

• Streptococci, rarely staphylococci and other forms of bacteria.

Typical symptoms:

• inflammation of the tonsils with a whitish coating on them, pain when swallowing, hoarseness, high fever, no rhinitis.

Disease risk:

• if a sore throat is not treated well enough, rheumatoid heart disease can become a complication - harmful bacteria spread through the blood and lead to heart valve defects. As a result, heart failure may develop.

Whooping cough is a dangerous infectious disease that mainly affects children. Highly contagious, the bacterium is transmitted by airborne droplets, therefore, without a sufficient level of immunization of the population, epidemics are easily caused.

Pathogen:

• Bordetella pertussis.

Typical symptoms:

• the disease at first proceeds like a common cold, later a characteristic paroxysmal barking cough appears, which may not go away for 2 months, after an attack the child may vomit.

Disease risk:

• Whooping cough is most dangerous for children of the first year of life, as it can cause respiratory arrest and death. Typical complications are pneumonia, bronchitis, false croup. From severe coughing attacks, it is extremely rare for a cerebral hemorrhage or pneumothorax to occur.

Pneumonia

Inflammation of the lungs can be caused by bacteria and viruses, as well as some fungi. Bacterial pneumonia, the most common complication of viral respiratory infections, can develop after the flu. Also, the multiplication of bacteria in the lungs is typical for bedridden patients, the elderly, patients with chronic lung diseases and respiratory disorders, with dehydration.

Pathogen:

• Staphylococci, pneumococci, Pseudomonas aeruginosa and others.

Typical symptoms:

• severe fever (up to 39 ° C and above), cough with copious moist greenish or yellowish sputum, chest pain, shortness of breath, feeling short of breath.

Disease risk:

• depends on the pathogen. With insufficient treatment, respiratory arrest and death are possible.

Tuberculosis

Tuberculosis is one of the most dangerous lung diseases that is difficult to treat. In Russia, tuberculosis has been a socially significant disease since 2004, since the number of infected people is much higher than in developed countries. Back in 2013, up to 54 cases of infection per 100,000 people were recorded.

Pathogen:

• mycobacterium, Koch's bacillus.

Typical symptoms:

• the disease may not manifest itself for a long time, then a cough occurs, a general malaise, a person loses weight, a subfebrile temperature (37-38 ° C) is observed for a month or more, a painful blush. Later, hemoptysis and severe pain appear.

Disease risk:

• features of the bacteria that cause tuberculosis is the development of resistance to antibiotics. Therefore, the infection is difficult to treat and can lead to death or disability. Common complications are heart disease.

Diphtheria is an infectious disease that in 90% of cases affects the upper respiratory tract. Diphtheria is especially dangerous for young children.

Pathogen:

• Corynebacterium diphtheriae (Leffler's bacillus).

Typical symptoms:

• pain when swallowing, hyperemia of the tonsils and specific white films on them, swollen lymph nodes, shortness of breath, high fever, general intoxication of the body.

Disease risk:

• Without timely treatment, diphtheria is fatal. The bacterial cell is capable of producing exotoxin, so the sick person can die from poisoning, in which the heart and nervous system are affected.

Intestinal infections

salmonellosis

Salmonellosis is one of the most common intestinal infections that can occur in different forms. Sometimes bacteria cause severe lesions, but there are times when the disease is mild or no symptoms at all.

Pathogen:

• Salmonella.

Typical symptoms:

• high temperature (up to 38-39 ° C), chills, abdominal pain, vomiting, diarrhea, severe intoxication of the body, in which a person sharply weakens.

Disease risk:

• Depending on the form of the course, in severe infections, bacterial toxins can lead to kidney failure or peritonitis. Children are at risk of dehydration.

Dysentery

Dysentery is an intestinal infection that affects people of all ages. Most often recorded in the summer hot period.

Pathogen:

• 4 types of Shigella bacteria.

Typical symptoms:

• Loose stools of dark green color with impurities of blood and pus, nausea, headaches, loss of appetite.

Disease risk:

• dehydration, which leads to the attachment of various inflammations, as well as intoxication of the body. With proper treatment, good immunity and sufficient fluid intake, the life of Shigella bacteria stops in 7-10 days. Otherwise, a serious complication is possible - intestinal perforation.

Gonorrhea

Gonorrhea is transmitted exclusively through sexual contact, but in rare cases, the infection can be passed from mother to child during childbirth (the baby develops conjunctivitis). The bacteria that causes gonorrhea can grow in the anus or throat, but it most often affects the genitals.

Pathogen:

• Gonococcus.

Typical symptoms:

• possible asymptomatic course of the disease: in men in 20%, in women - more than 50%. In the acute form, there are pains during urination, white-yellow discharge from the penis and vagina, burning and itching.

Disease risk:

• If left untreated, the infection can cause infertility and can also damage the skin, joints, cardiovascular system, liver, and brain.

Syphilis

Syphilis is characterized by slow progression, symptoms appear gradually and do not develop quickly. The characteristic course of the disease is an alternation of exacerbations and remissions. Household infection, many doctors question, in the vast majority of cases, bacteria are transmitted to humans sexually.

Pathogen:

• Pale treponema.

Typical symptoms:

• at the first stage, an ulcer appears on the genitals, which heals on its own in 1-1.5 months, an increase in lymph nodes is observed. After, after 1-3 months, a pale rash appears all over the body, the patient feels weak, the temperature may rise, the symptoms resemble the flu.

Disease risk:

• pathogenic bacteria eventually lead to the development of tertiary syphilis (30% of all infected), which affects the aorta, brain and back, brain, bones and muscles. Perhaps the development of damage to the nervous system - neurosyphilis.

Chlamydia

Chlamydia is a sexually transmitted infection that is often asymptomatic. In addition, pathogenic bacteria are difficult to detect; PCR analysis is prescribed for diagnosis.

Pathogen:

• Chlamydia.

Typical symptoms:

• in the acute form, discharge from the genital organs (usually transparent), pain during urination, blood discharge are observed.

Disease risk:

• in men - inflammation of the epididymis, in women - inflammation of the uterus and appendages, infertility, Reiter's syndrome (inflammation of the urethra).

Meningococcal infection

Meningococcal infection is a group of diseases caused by one pathogen, but occurring in different forms. A person may be an asymptomatic carrier of the bacterium, and in other cases, the microbe causes a generalized infection leading to death.

Pathogen:

• Meningococcus.

Typical symptoms:

• vary with the severity of the disease. The infection can manifest itself as a mild cold, in severe cases, meningococcemia develops, characterized by an acute onset of the disease, the appearance of a red rash (does not disappear with pressure), the temperature rises, confusion is observed.

Disease risk:

• in severe form, tissue necrosis develops, gangrene of the fingers and extremities, and brain damage are possible. With the development of infectious-toxic shock, death quickly occurs.

Tetanus

Tetanus is a dangerous infection that develops in wounds on the skin. The causative agent forms spores of bacteria, in the form of which it is found in the external environment. When it enters the wound, it quickly germinates. Therefore, any serious injury requires the prevention of infection - the introduction of tetanus toxoid.

Pathogen:

• Tetanus stick.

Typical symptoms:

• tetanus affects the central nervous system, at first it is manifested by tonic tension of the jaw muscles (it is difficult for a person to speak, open his mouth), later it spreads to the whole body, the patient arches due to muscle hypertonicity, and at the end respiratory failure develops.

Disease risk:

• the main danger is the toxin that the bacterium secretes, it is he who leads to severe symptoms. As a result of poisoning, tonic tension of all muscles occurs, including the diaphragm and intercostal muscles, as a result of which a person cannot breathe and dies from hypoxia.

Treatment of bacterial diseases

Any bacterial infection needs planned treatment, because bacteria can cause serious damage to the body. Only the doctor chooses the appropriate treatment regimen, which depends not only on the type of disease, but also on the severity of the course.

Antibiotics

Antibiotics are considered the mainstay of treatment for all infections caused by harmful bacteria. Since the discovery of penicillin in the 1920s, many diseases have been moved from fatal to curable. The number of complications after operations has decreased, and, from which every fourth person died, remained a dangerous disease only for people from risk groups.

Modern antibiotics can be divided into two groups:

• Bactericidal - kill pathogenic bacteria.
• Bacteriostatic - slow down the growth, stop the reproduction of bacteria.

The former have a more pronounced effect, however, it is the drugs from the second group that are prescribed more often, since, as a rule, they cause fewer complications.

It is also customary to divide drugs according to the spectrum of action:

• Broad-spectrum antibiotics (penicillins, tetracyclines, macrolides) are used to kill different types of bacteria. They are effective in the case when treatment needs to be started urgently, even before the tests. Penicillins are most commonly prescribed for respiratory bacterial infections.
• Antibiotics that are active against a limited number of bacterial species (often prescribed for tuberculosis and other specific infections).

Any antibiotics must be taken in a course, because if treatment is interrupted, the remaining living bacteria quickly restore the colony.

Problems in the use of antibiotics

Despite the widespread use of antibiotics, doctors today are looking for alternative drugs to treat bacterial infections. This is due to several significant disadvantages of these drugs:

• Development of resistance in bacteria.

Many microorganisms have developed defense mechanisms against drugs, and the use of classical antibiotics is no longer effective. For example, first-generation penicillins, which actively fought against staphylococci and streptococci, are not used today. Staphylococcus aureus has learned to synthesize the enzyme penicillinase, which destroys the antibiotic. Of particular danger are new strains of bacteria that have developed resistance to the latest generation of drugs - the so-called superbugs. The most famous of these is methicillin-resistant Staphylococcus aureus. Also, Pseudomonas aeruginosa and enterococci quickly develop resistance.

• The use of broad-spectrum antibiotics leads to dysbacteriosis.

After such treatment, the balance of microflora is significantly disturbed, complications often develop, the body is weakened not only by the disease, but also by the action of drugs. The use of medicines is limited among certain population groups: pregnant women, children, patients with liver and kidney damage, and other categories.

bacteriophages

An alternative to antibiotics could be bacteriophages, viruses that kill a specific class of bacteria. Among the advantages of such drugs:

• Low likelihood of developing resistance, since bacteriophages are organisms that have lived on Earth for several billion years and continue to infect bacterial cells.
• They do not violate the microflora, since they are specialized medicines - effective only in relation to a specific type of microorganisms.
• Can be used by people at risk.

Preparations containing bacteriophages are already available in pharmacies today. But still, such therapy is losing to antibiotics. Many diseases require immediate treatment, which means that broad-spectrum drugs are needed, while bacteriophages are highly specialized - they can be prescribed only after the pathogen has been identified. In addition, currently known viruses are not able to destroy such a large list of pathogenic bacteria as antibiotics.

Other treatments

WHO does not recommend the use of antibiotics for all types of bacterial infections. In the event that the microbe does not have a high pathogenicity, and the disease proceeds without complications, symptomatic treatment is sufficient - the use of antipyretics, painkillers, vitamin complexes, heavy drinking and other things. Often the immune system itself can suppress the reproduction of a colony of pathogenic microorganisms. However, in this case, the patient must be under the supervision of a doctor who will decide on the appropriateness of a particular method of therapy.

Effective vaccines have been developed for many deadly bacterial infections. Vaccinations are recommended for the following diseases:

• Tuberculosis.
• Haemophilus infection.
• Pneumococcal infection.
• Diphtheria (toxoid is used - a vaccine that helps produce antibodies to the toxin of the bacterium).
• Tetanus (toxoid is used).

Bacteria, nutrition and digestion

The live bacteria in foods alone can restore the gut microflora, help the digestive tract, and get rid of toxins. Others, on the contrary, getting into the digestive tract with food, cause dangerous infections and serious poisoning.

• Pathogenic bacteria often multiply in products with violations of storage rules. And breeding anaerobic bacteria are especially dangerous here, which easily increase their numbers even in goods in sealed packaging and canned food.
• Another way of food contamination is through unwashed hands or equipment (knives, cutting boards, etc.). Therefore, food poisoning is easy to get after street food, which was prepared without observing sanitary standards.
• Insufficient heat treatment or its absence also increases the likelihood of the reproduction of various pathogenic forms of bacteria.

Medicines with live bacteria

Preparations with beneficial live bacteria are often recommended by nutritionists for various disorders of the gastrointestinal tract. They help with bloating, flatulence, heaviness, poor digestion of food, frequent poisoning.

In the event that dysbacteriosis is severe, the doctor may recommend a course of drugs to restore microflora.

• Probiotics are products that contain live beneficial bacteria.

The drug is available in capsules with a shell that protects the colonies of microorganisms and helps to deliver them to the intestines in a living form.

• Prebiotics are carbohydrate preparations that contain nutrients for beneficial bacteria.

Such drugs are prescribed if the intestines are inhabited by bifidus and lactobacilli, but their colonies are not large enough.

Lactic acid bacteria are an extensive group of microorganisms that are able to process glucose with the release of lactic acid. In fact, this means that it is precisely these microbes that are involved in the process of fermenting milk - with their help, all fermented milk products are created. Food does not spoil longer precisely thanks to lactic acid bacteria - the acidic environment that they create prevents the growth of pathogens. They exhibit the same protective functions in the human intestine.

The main products in which lactic acid bacteria are present:

• Yogurt without additives.
• Starter cultures, kefir and other fermented milk drinks.
• acidophilus milk.
• Hard cheeses.
• Sauerkraut.

Tables of the main bacteria

Pathogenic bacteria

Bacteria in the table are presented by the main types of microbes that can cause disease. However, many of them also include non-pathogenic or opportunistic bacteria.

Name	bacteria	Type of breath		Diseases caused by bacteria
Staphylococci		Facultative anaerobes		Staphylococcus aureus provokes most purulent diseases. Including: skin lesions, pneumonia, sepsis. Staphylococcus epidermidis causes purulent complications in the postoperative period, and saprophytic - cystitis and urethritis (bacteria are found in the urine).
streptococci		Facultative anaerobes		Scarlet fever, rheumatism (acute rheumatic fever), tonsillitis, pharyngitis, pneumonia, endocarditis, meningitis, abscess.
Clostridia		anaerobic bacteria		Bacteria can be part of a healthy microflora. At the same time, some species are able to secrete the strongest known poison - exotoxin botulinum toxin. Clostridia are the causative agents of tetanus, gas gangrene, and botulism.
		Aerobes, facultative anaerobes		Certain types of bacteria cause anthrax and intestinal infections. The genus also includes Escherichia coli - a representative of healthy microflora.
Enterococci		Facultative anaerobes		Urinary tract infections, endocarditis, meningitis, sepsis.

Beneficial bacteria

The table of bacteria represents the types of microbes that are vital to humans.

Name	bacteria shape	Type of breath	Benefits for the body
bifidobacteria		Anaerobes	Human bacteria, which are part of the intestinal and vaginal microflora, help normalize digestion (drugs with bifidobacteria are prescribed for diarrhea), assimilate vitamins. The peculiarity of bacteria is that they prevent the reproduction of staphylococci, shigella, candida fungus.
	Cocci, sticks	Aerobes requiring reduced oxygen concentration (microaerophilic bacteria)	A group of bacteria that is united by one characteristic - the ability to cause lactic acid fermentation. Used in the food industry, are part of probiotics.

Bacteria have been living on planet Earth for more than 3.5 billion years. During this time they have learned a lot and adapted to a lot. Now they are helping people. Bacteria and man became inseparable. The total mass of bacteria is enormous. It is about 500 billion tons.

Beneficial bacteria perform two of the most important ecological functions - they fix nitrogen and participate in the mineralization of organic residues. The role of bacteria in nature is global. They are involved in the movement, concentration and dispersion of chemical elements in the earth's biosphere.

The importance of bacteria beneficial to humans is great. They make up 99% of the entire population that inhabit his body. Thanks to them, a person lives, breathes and eats.

Important. They provide complete life support.

Bacteria are pretty simple. Scientists suggest that they first appeared on planet Earth.

Beneficial bacteria in the human body

The human body is inhabited by both useful and. The existing balance between the human body and bacteria has been polished for centuries.

As scientists have calculated, the human body contains from 500 to 1000 different types of bacteria, or trillions of these amazing tenants, which is up to 4 kg of total weight. Up to 3 kilograms of microbial bodies is found only in the intestines. The rest of them are in the urogenital tract, on the skin and other cavities of the human body. Microbes fill the body of a newborn from the first minutes of his life and finally form the composition of the intestinal microflora by 10-13 years.

Streptococci, lactobacilli, bifidobacteria, enterobacteria, fungi, intestinal viruses, non-pathogenic protozoa live in the intestine. Lactobacilli and bifidobacteria make up 60% of the intestinal flora. The composition of this group is always constant, they are the most numerous and perform the main functions.

bifidobacteria

The importance of this type of bacteria is enormous.

• Thanks to them, acetate and lactic acid are produced. By acidifying their habitat, they inhibit the growth that causes decay and fermentation.
• Thanks to bifidobacteria, the risk of developing food allergies in babies is reduced.
• They provide antioxidant and antitumor effects.
• Bifidobacteria are involved in the synthesis of vitamin C.
• Bifido- and lactobacilli are involved in the absorption of vitamin D, calcium and iron.

Rice. 1. The photo shows bifidobacteria. Computer visualization.

coli

The importance of this type of bacteria for humans is great.

• Special attention is paid to the representative of this genus Escherichia coli M17. It is able to produce the substance cocilin, which inhibits the growth of a number of pathogenic microbes.
• With the participation, vitamins K, group B (B1, B2, B5, B6, B7, B9 and B12), folic and nicotinic acids are synthesized.

Rice. 2. The photo shows E. coli (3D computer image).

The positive role of bacteria in human life

• With the participation of bifido-, lacto-, and enterobacteria, vitamins K, C, group B (B1, B2, B5, B6, B7, B9 and B12), folic and nicotinic acids are synthesized.
• Due to the breakdown of undigested food components from the upper intestines - starch, cellulose, protein and fat fractions.
• The intestinal microflora maintains water-salt metabolism and ionic homeostasis.
• Due to the secretion of special substances, the intestinal microflora inhibits the growth of pathogenic bacteria that cause putrefaction and fermentation.
• Bifido-, lacto-, and enterobacteria take part in the detoxification of substances that enter from the outside and are formed inside the body itself.
• The intestinal microflora plays an important role in restoring local immunity. Thanks to it, the number of lymphocytes, the activity of phagocytes and the production of immunoglobulin A increase.
• Thanks to the intestinal microflora, the development of the lymphoid apparatus is stimulated.
• The resistance of the intestinal epithelium to carcinogens increases.
• Microflora protect the intestinal mucosa and provide energy to the intestinal epithelium.
• They regulate intestinal motility.
• The intestinal flora acquires the skills to capture and remove viruses from the host organism, with which it has been in symbiosis for many years.
• The importance of bacteria in maintaining the body's thermal balance is great. The intestinal microflora feeds on substances that are not digested by the enzymatic system, which come from the upper gastrointestinal tract. As a result of complex biochemical reactions, a huge amount of thermal energy is produced. Heat is carried throughout the body with blood flow and enters all internal organs. That is why a person always freezes when starving.
• The intestinal microflora regulates the reabsorption of bile acid components (cholesterol), hormones, etc.

Rice. 3. In the photo, beneficial bacteria are lactobacilli (3D computer image).

The role of bacteria in nitrogen production

ammonifying microbes(causing decay), with the help of a number of enzymes they have, they are able to decompose the remains of dead animals and plants. When proteins decompose, nitrogen and ammonia are released.

Urobacteria decompose urea, which man and all animals of the planet secrete daily. Its quantity is huge and reaches 50 million tons per year.

A certain type of bacteria is involved in the oxidation of ammonia. This process is called nitrofication.

Denitrifying microbes return molecular oxygen from the soil to the atmosphere.

Rice. 4. In the photo, beneficial bacteria are ammonifying microbes. They expose the remains of dead animals and plants to decomposition.

The role of bacteria in nature: nitrogen fixation

The importance of bacteria in the life of humans, animals, plants, fungi and bacteria is enormous. As you know, nitrogen is necessary for their normal existence. But bacteria cannot absorb nitrogen in the gaseous state. It turns out that blue-green algae can bind nitrogen and form ammonia ( cyanobacteria), free-living nitrogen fixers and special . All these useful bacteria produce up to 90% of the bound nitrogen and involve up to 180 million tons of nitrogen in the nitrogen fund of the soil.

Nodule bacteria coexist well with leguminous plants and sea buckthorn.

Plants such as alfalfa, peas, lupins and other legumes have so-called "apartments" for nodule bacteria on their roots. These plants are planted on depleted soils to enrich them with nitrogen.

Rice. 5. The photo shows nodule bacteria on the surface of the root hair of a legume plant.

Rice. 6. Photo of the root of a leguminous plant.

Rice. 7. In the photo, beneficial bacteria are cyanobacteria.

The role of bacteria in nature: the carbon cycle

Carbon is the most important cellular substance of the animal and plant world, as well as the plant world. It makes up 50% of the dry matter of the cell.

A lot of carbon is found in the fiber that animals eat. In their stomach, fiber decomposes under the action of microbes and then, in the form of manure, gets outside.

Decompose fiber cellulose bacteria. As a result of their work, the soil is enriched with humus, which significantly increases its fertility, and carbon dioxide is returned to the atmosphere.

Rice. 8. Intracellular symbionts are colored green, the mass of processed wood is colored yellow.

The role of bacteria in the conversion of phosphorus, iron and sulfur

Proteins and lipids contain a large amount of phosphorus, the mineralization of which is carried out You. megatherium(from the genus of putrefactive bacteria).

iron bacteria participate in the processes of mineralization of organic compounds containing iron. As a result of their activities, a large amount of iron ore and ferromanganese deposits are formed in swamps and lakes.

Sulfur bacteria live in water and soil. There are many of them in manure. They participate in the process of mineralization of sulfur-containing substances of organic origin. In the process of decomposition of organic sulfur-containing substances, hydrogen sulfide gas is released, which is extremely toxic to the environment, including to all living things. Sulfur bacteria, as a result of their vital activity, turn this gas into an inactive, harmless compound.

Rice. 9. Despite the apparent lifelessness, there is still life in the Rio Tinto River. These are various iron-oxidizing bacteria and many other species that can only be found in this place.

Rice. 10. Green sulfur bacteria in the Winogradsky column.

The role of bacteria in nature: mineralization of organic residues

Bacteria that take an active part in the mineralization of organic compounds are considered cleaners (orderlies) of the planet Earth. With their help, the organic matter of dead plants and animals turns into humus, which soil microorganisms turn into mineral salts, which are so necessary for building the root, stem and leaf systems of plants.

Rice. 11. Mineralization of organic substances entering the reservoir occurs as a result of biochemical oxidation.

The role of bacteria in nature: fermentation of pectins

The cells of plant organisms bind to each other (cement) with a special substance called pectin. Some types of butyric acid bacteria have the ability to ferment this substance, which, when heated, turns into a gelatinous mass (pectis). This feature is used when soaking plants containing a lot of fibers (flax, hemp).

Rice. 12. There are several ways to obtain trusts. The most common is the biological method, in which the connection of the fibrous part with the surrounding tissues is destroyed under the influence of microorganisms. The process of fermentation of pectin substances of bast plants is called lobe, and soaked straw is called trust.

The role of bacteria in water purification

water purifying bacteria, stabilize the level of its acidity. With their help, bottom sediments are reduced, the health of fish and plants living in the water improves.

Recently, a group of scientists from different countries have discovered bacteria that destroy detergents that are part of synthetic detergents and some drugs.

Rice. 13. The activity of xenobacteria is widely used to clean up soils and water bodies contaminated with oil products.

Rice. 14. Plastic domes that purify water. They contain heterotrophic bacteria that feed on carbon-containing materials and autotrophic bacteria that feed on ammonia and nitrogen-containing materials. The tube system keeps them alive.

The use of bacteria in the enrichment of ores

Ability thionic sulfur-oxidizing bacteria used to enrich copper and uranium ores.

Rice. 15. In the photo, beneficial bacteria are Thiobacilli and Acidithiobacillus ferrooxidans (electron micrograph). They are able to extract copper ions for leaching of wastes that are formed during the flotation enrichment of sulfide ores.

The role of bacteria in butyric fermentation

Butyric microbes are everywhere. There are more than 25 types of these microbes. They take part in the process of decomposition of proteins, fats and carbohydrates.

Butyric fermentation is caused by anaerobic spore-forming bacteria belonging to the genus Clostridium. They are able to ferment various sugars, alcohols, organic acids, starch, fiber.

Rice. 16. In the photo, butyric microorganisms (computer visualization).

The role of bacteria in animal life

Many species of the animal world feed on plants, which are based on fiber. To digest fiber (cellulose) animals are helped by special microbes, the residence of which is certain sections of the gastrointestinal tract.

Importance of bacteria in animal husbandry

The vital activity of animals is accompanied by the release of a huge amount of manure. From it, some microorganisms can produce methane ("marsh gas"), which is used as a fuel and raw material in organic synthesis.

Rice. 17. Methane gas as a fuel for cars.

The use of bacteria in the food industry

The role of bacteria in human life is enormous. Lactic acid bacteria are widely used in the food industry:

• in the production of curdled milk, cheeses, sour cream and kefir;
• when fermenting cabbage and pickling cucumbers, they take part in urinating apples and pickling vegetables;
• they give a special flavor to wines;
• produce lactic acid, which ferments milk. This property is used for the production of curdled milk and sour cream;
• in the preparation of cheeses and yogurts on an industrial scale;
• lactic acid serves as a preservative during the brining process.

Lactic acid bacteria are milk streptococci, creamy streptococci, bulgarian, acidophilic, grain thermophilic and cucumber sticks. Bacteria of the genus Streptococcus and Lactobacillus give the products a thicker consistency. As a result of their vital activity, the quality of cheeses improves. They give the cheese a certain cheese flavor.

Rice. 18. In the photo, beneficial bacteria are lactobacilli (pink), Bulgarian stick and thermophilic streptococcus.

Rice. 19. In the photo, beneficial bacteria are kefir (Tibetan or milk) mushroom and lactic acid sticks before being directly introduced into milk.

Rice. 20. Dairy products.

Rice. 21. Thermophilic streptococci (Streptococcus thermophilus) are used in the preparation of mozzarella cheese.

Rice. 22. There are many options for mold penicillin. Velvety crust, greenish veins, unique taste and medicinal ammonia aroma of cheeses are unique. The mushroom taste of cheeses depends on the place and duration of ripening.

Rice. 23. Bifiliz - a biological preparation for oral administration, containing a mass of live bifidobacteria and lysozyme.

The use of yeast and fungi in the food industry

The food industry mainly uses the yeast species Saccharomyces cerevisiae. They carry out alcoholic fermentation, which is why they are widely used in the baking business. The alcohol evaporates during baking, and carbon dioxide bubbles form the bread crumb.

Since 1910, yeast has been added to sausages. Yeast of the species Saccharomyces cerevisiae is used for the production of wines, beer and kvass.

Rice. 24. Kombucha is a friendly symbiosis of vinegar sticks and yeast. It appeared in our area in the last century.

Rice. 25. Dry and wet yeast are widely used in the baking industry.

Rice. 26. Microscopic view of Saccharomyces cerevisiae yeast cells and Saccharomyces cerevisiae - "real" wine yeast.

The role of bacteria in human life: acetic acid oxidation

Pasteur also proved that special microorganisms take part in acetic acid oxidation - vinegar sticks which are widely found in nature. They settle on plants, penetrate into ripened vegetables and fruits. There are many of them in pickled vegetables and fruits, wine, beer and kvass.

The ability of vinegar sticks to oxidize ethyl alcohol to acetic acid is used today to produce vinegar used for food purposes and in the preparation of animal feed - ensiling (canning).

Rice. 27. The process of ensiling fodder. Silage is a succulent feed with a high nutritional value.

The role of bacteria in human life: the production of drugs

The study of the vital activity of microbes has allowed scientists to use some bacteria for the synthesis of antibacterial drugs, vitamins, hormones and enzymes.

They help fight many infectious and viral diseases. Most antibiotics are produced actinomycetes, less often non-micellar bacteria. Penicillin, derived from fungi, destroys the cell wall of bacteria. Streptomycetes produce streptomycin, which inactivates the ribosomes of microbial cells. hay sticks or Bacillus subtilis acidify the environment. They inhibit the growth of putrefactive and conditionally pathogenic microorganisms due to the formation of a number of antimicrobial substances. Hay stick produces enzymes that destroy substances that are formed as a result of the putrefactive decay of tissues. They are involved in the synthesis of amino acids, vitamins and immunoactive compounds.

Using the technology of genetic engineering, today scientists have learned to use for the production of insulin and interferon.

A number of bacteria are supposed to be used to produce a special protein that can be added to livestock feed and human food.

Rice. 28. In the photo, spores of hay bacillus or Bacillus subtilis (painted blue).

Rice. 29. Biosporin-Biopharma is a domestic drug containing apathogenic bacteria of the genus Bacillus.

Using bacteria to produce safe herbicides

Today, the technique is widely used phytobacteria for the production of safe herbicides. toxins Bacillus thuringiensis emit Cry-toxins dangerous for insects, which makes it possible to use this feature of microorganisms in the fight against plant pests.

The use of bacteria in the production of detergents

Proteases or cleave peptide bonds between the amino acids that make up proteins. Amylase breaks down starch. hay stick (B. subtilis) produces proteases and amylases. Bacterial amylases are used in the manufacture of laundry detergent.

Rice. 30. The study of the vital activity of microbes allows scientists to apply some of their properties for the benefit of man.

The importance of bacteria in human life is enormous. Beneficial bacteria have been constant companions of man for many millennia. The task of mankind is not to disturb this delicate balance that has developed between the microorganisms living inside us and in the environment. The role of bacteria in human life is enormous. Scientists are constantly discovering the beneficial properties of microorganisms, the use of which in everyday life and in production is limited only by their properties.

Articles in the section "What do we know about microbes"Most popular

Where do bacteria live in the human body?

1. Most of them inhabit the intestines, providing a harmonious microflora.
2. They live on mucous membranes, including in the oral cavity.
3. Many microorganisms inhabit the skin.

What are microorganisms responsible for?

1. They support immune function. With a lack of beneficial microbes, the body is immediately attacked by harmful ones.
2. By feeding on the components of plant foods, bacteria help digestion. Most of the food that reaches the large intestine is digested thanks to bacteria.
3. Benefits of intestinal microorganisms - in the synthesis of B vitamins, antibodies, absorption of fatty acids.
4. The microbiota maintains the water-salt balance.
5. Bacteria on the skin protect the integument from the penetration of harmful microorganisms into them. The same applies to the population of mucous membranes.

What happens if you remove bacteria from the human body? Vitamins will not be absorbed, hemoglobin will fall in the blood, diseases of the skin, gastrointestinal tract, respiratory organs, etc. will begin to progress. Conclusion: the main function of bacteria in the human body is protective. Let's take a closer look at what types of microorganisms exist and how to support their work.

Major groups of beneficial bacteria

Good bacteria for humans can be divided into 4 main groups:

• bifidobacteria;
• lactobacilli;
• enterococci;
• coli.

The most abundant beneficial microbiota. The task is to create an acidic environment in the intestines. In such conditions, pathogenic microflora cannot survive. Bacteria produce lactic acid and acetate. Thus, the intestinal tract is not afraid of the processes of fermentation and decay.

Another property of bifidobacteria is antitumor. Microorganisms are involved in the synthesis of vitamin C - the main antioxidant in the body. Vitamins D and B-group are absorbed thanks to this type of microbe. The digestion of carbohydrates is also accelerated. Bifidobacteria increase the ability of the intestinal walls to absorb valuable substances, including calcium, magnesium and iron ions.

Lactobacilli live in the digestive tract from the mouth to the large intestine. The joint action of these bacteria and other microorganisms controls the reproduction of pathogenic microflora. Intestinal pathogens are much less likely to infect the system if lactobacilli inhabit it in sufficient numbers.

The task of little hard workers is to normalize the work of the intestinal tract and support immune function. The microbiota is used in the food and medical industries: from healthy kefir to preparations for the normalization of the intestinal microflora.

Lactobacilli are especially valuable for women's health: the acidic environment of the mucous membranes of the reproductive system does not allow the development of bacterial vaginosis.

Advice! Biologists say that the immune system starts in the gut. The body's ability to resist harmful bacteria depends on the condition of the tract. Keep the digestive tract normal, and then not only the absorption of food will improve, but the body's defenses will also increase.

Enterococci

The habitat of enterococci is the small intestine. They block the reproduction of pathogenic microorganisms, help to digest sucrose.

The Polzateevo magazine found out that there is an intermediate group of bacteria - conditionally pathogenic. In one state, they are beneficial, and when any conditions change, they become harmful. These include enterococci. Staphylococci living on the skin also have a dual effect: they protect the integument from harmful microbes, but they themselves are able to get into the wound and cause a pathological process.

E. coli often causes negative associations, but only some species from this group bring harm. Most Escherichia coli have a beneficial effect on the tract.

These microorganisms synthesize a number of B vitamins: folic and nicotinic acid, thiamine, riboflavin. An indirect effect of such synthesis is an improvement in the composition of the blood.

What bacteria are harmful

Harmful bacteria are more widely known than beneficial ones, as they pose a direct threat. Many people know the dangers of salmonella, plague bacillus and vibrio cholerae.

The most dangerous bacteria for humans:

1. Tetanus bacillus: Lives on the skin and can cause tetanus, muscle spasms, and respiratory problems.
2. Botulism stick. If you eat a spoiled product with this pathogen, you can earn a deadly poisoning. Botulism often develops in expired sausages and fish.
3. Staphylococcus aureus can cause several ailments in the body at once, is resistant to many antibiotics and adapts incredibly quickly to drugs, becoming insensitive to them.
4. Salmonella is the cause of acute intestinal infections, including a very dangerous disease - typhoid fever.

Prevention of dysbacteriosis

Living in an urban environment with poor ecology and nutrition significantly increases the risk of dysbacteriosis - an imbalance of bacteria in the human body. Most often, the intestines suffer from dysbacteriosis, less often the mucous membranes. Signs of a lack of beneficial bacteria: gas formation, bloating, abdominal pain, upset stool. If you start the disease, vitamin deficiency, anemia, an unpleasant smell of the mucous membranes of the reproductive system, weight loss, and skin defects may develop.

Dysbacteriosis easily develops in conditions of taking antibiotic drugs. To restore the microbiota, probiotics are prescribed - formulations with living organisms and prebiotics - preparations with substances that stimulate their development. Fermented milk drinks containing live bifidus and lactobacilli are also considered useful.

In addition to therapy, the beneficial microbiota responds well to fasting days, eating fresh fruits and vegetables, and whole grains.

The role of bacteria in nature

The kingdom of bacteria is one of the most numerous on the planet. These microscopic creatures bring benefits and harm not only to humans, but also to all other species, provide many processes in nature. Bacteria are found in the air and in the soil. Azotobacter are very useful inhabitants of the soil, which synthesize nitrogen from the air, turning it into ammonium ions. In this form, the element is easily absorbed by plants. The same microorganisms cleanse soils from heavy metals and fill them with biologically active substances.

Do not be afraid of bacteria: our body is so arranged that it cannot function normally without these tiny hard workers. If their number is normal, then the immune, digestive and a number of other functions of the body will be in order.