Distribution of bacteria in air, soil, water, living organisms. Bacteria

Distributed everywhere, especially in soil. Small colonies form on the surface of soil particles. The number of bacteria in the soil is not constant, fluctuates, and is varied in composition (nitrifying, rotting, nitrogen-fixing, etc.). Promote soil formation processes.

Many bacteria surround the roots of plants, their special zone - the rhizosphere. Some bacteria enter into symbiosis with plants and form bacteriorrhiza.

The majority of bacteria enter water from the soil. The least amount of bacteria is in artesian wells and springs. The largest number of bacteria is concentrated in the upper layers of reservoirs, closer to the shore. They can be stored in water for a long time. With increasing depth and distance from the shore, the number of bacteria decreases. A large number of bacteria, especially their spores (about 75%), in the bottom mud, especially in the upper layers, where they can form a film. In terms of species composition, the microflora of water is similar to soil. There are specific bacteria in water. Bacteria contribute to the biological purification of water (destroy various residues).

The number of bacteria in the air is lower than in soil and water. They die from ultraviolet rays. Colored bacteria and spores are more resistant to ultraviolet rays. They can rise into the air along with dust and remain there for a long time, and then settle on the surface. The amount of bacteria in the air depends on various factors (climate, time of year). There are many bacteria in polluted air. Clean air over forests, mountains, snow covers.

Microflora of the human body. Pathogenic bacteria

Bacteria live in the body of every person. There are especially many of them in the large intestine. An excellent habitat for bacteria is the oral cavity (there are more than 100 species), small and large intestines, which have an alkaline reaction that is favorable for microflora. Bacteria are constantly released into the external environment in large numbers.

Open areas of the body and clothing are contaminated with bacteria. Almost all known microflora is observed on the hands. Pathogenic microorganisms can enter the human body. Microorganisms that cause infectious diseases are called pathogenic , or pathogenic . One of these microorganisms is bacteria. They are able to penetrate tissues and organs, secrete substances that are active even in small doses, which destroy the body’s protective barriers. These substances affect connective tissue, act as enzymes, enhance the pathogenic power of organisms, and thus cause invasive properties of bacteria. Pathogens can be transmitted by droplets, through objects, food, water, through injury, or through direct contact.

There are two known groups of substances that produce pathogenic bacteria: aggressors and toxins. Aggressins suppress the body's defenses, enhance the pathogenic effect of pathogens.

Toxins - These are waste products of bacteria that have poisonous properties. The toxins that bacteria release into their environment are very strong and are called exotoxins . They are formed by staphylococci, the causative agent of tetanus, streptococci, diphtheria bacillus, etc.

If toxins are released only after the death and destruction of the cell, then they are called endotoxins . They are formed by pneumococci, Vibrio cholerae, tuberculosis bacillus (Koch), the causative agent of anthrax, etc.

The internal organs of a person are almost free of bacteria, so even non-pathogenic microorganisms getting there through the blood or other routes can cause inflammation and disease. Bacteria that live as saprophytes, but can cause diseases when the body is weakened, are called conditionally pathogenic . An example would be Escherichia coli, which is a common saprophyte of the intestine. Under unfavorable conditions, it can cause inflammation in the kidneys, bladder and other organs.

The importance of bacteria

Bacteria play an important role in the cycle of substances: nitrogen, carbon, sulfur, iron. They carry out chemical transformations (chemosynthesis) that are inaccessible to either plants or animals. Bacteria contribute to soil formation processes and process (mineralize) the remains of organisms.

Some purple and green sulfur bacteria are capable of photosynthesis. They play an important role in the sulfur cycle and form sulfates in the soil that are accessible to plants. Some processes that cause anaerobic bacteria are used in the food industry: lactic acid (production of fermented milk products, fermentation of vegetables, silage of feed, baking bread), propionic acid (in dairy cheese production), acetic acid (production of vinegar) fermentation, etc. With the help of bacteria receive medications and some chemicals.

They can enter into a mutualistic relationship with the host, like E. coli, which lives in the human large intestine or bacteria in the rumen of ruminants. Nodule bacteria enrich plants with available nitrogen compounds. Thanks to them, plants are able to absorb nitrogen from the atmosphere.

A number of bacteria are causative agents of diseases in plants, animals and humans.

Microorganisms in nature are found almost everywhere where life is possible. Therefore, they can be found in water, air, living organisms and especially in soil. Diverse in composition and function, they can both help more complex life forms and cause enormous harm. To understand how we can explain the widespread distribution of bacteria on our planet, it is worth considering the features of their survival on Earth in various environments and their significance for other forms of life.

The spread of most bacteria in the air is associated with constantly changing living conditions of plants, animals and humans, as well as seasonal temperature changes and climatic features. The lowest concentration of microorganisms in nature can be found in mountainous and marine environments, where their reproduction is somewhat difficult. Settlements, on the contrary, become the place of their greatest concentration, especially in the summer. The presence of microorganisms in the air is temporary, since it does not have sufficient nutrients.

In residential premises, the number of bacteria is approximately 1,500 representatives of the microcosm per 1 cubic meter. It is the air environment that becomes a transport for many pathogenic microorganisms that cause respiratory diseases, influenza, tuberculosis, etc. They are released into nature by their carrier and spread quite quickly over considerable distances. Good room ventilation significantly reduces the spread of harmful bacteria.

Spread in soil

The soil is a springboard from which bacteria enter both water and living organisms and air. One gram of it contains up to several billion microorganisms. They are classified as follows:

Putrefactive bacteria of the aerobic and anaerobic type are involved in the process of decomposition of organic matter.
Nitrogen-fixing - help plants absorb nitrogen by processing it from the air.
Nitrifying - work with more complex nitrogen compounds.
Actinomycetes (decompose the most stable substrates), etc.

Pathogenic bacteria enter the soil through the blood and secretions of a sick or dead organism and debris. The causative agents of many intestinal diseases live in the soil for more than a month. Gas gangrene spores, anthrax and tetanus can survive outside the host for several decades.

Distribution in the aquatic environment

Due to the fact that water is a more favorable habitat and reproduction on Earth, the number of microorganisms in it is several times higher. One cubic centimeter of liquid can contain up to a million microbes, but this is not of great importance, since most of them are not pathogens.

Most often, the spread of pathogenic microorganisms in nature occurs through surface waters of rivers, which are polluted by industrial waste from various enterprises, liquids flowing from populated areas, and rain. If all these factors cease to influence a certain place of the river, then the level of pollution decreases.

Water may contain pathogens of various diseases, such as:

dysentery;
typhoid fever;
colienteritis.

Once in water, bacteria can remain there for several months, increasing the risk of disease.

Distribution in the human body

Pathogenic microorganisms can enter the human body in many ways, but mainly this happens through the oral cavity and damaged areas of the skin. Many ingested bacteria live in a person without harming him. Since a huge number of microorganisms live in the oral cavity, it is from there that they spread throughout the body through the food and water consumed.

This cavity contains:

staphylococci;
streptococci;
micrococci.

Because of this, some inflammatory processes in the oral cavity can cause the disease. The spread of bacteria in the air, soil, water, and living organisms is explained by the huge diversity of their species, which have managed to adapt to almost any conditions of existence in nature.

But hands are most susceptible to contamination, since they often come into contact with various objects. They may contain pathogenic microorganisms that cause serious illness. The proliferation of such bacteria can be stopped by following simple hygiene rules, which is of no small importance in the prevention of most infections.

Food poisoning is a common consequence of infection with microorganisms in nature. But this happens only after the accumulation of a certain number of bacteria that produce toxins.

To prevent the spread of bacteria, you should wash your hands after many daily operations and before eating, this action has great importance and will allow you to maintain health for yourself and those around you.

Microorganisms are ubiquitous. The only exceptions are the craters of active volcanoes and small areas at the epicenters of exploded atomic bombs. Neither the low temperatures of Antarctica, nor the boiling streams of geysers, nor saturated salt solutions in salt pools, nor the strong insolation of mountain peaks, nor the harsh irradiation of nuclear reactors interfere with the existence and development of microflora. All living beings - plants, animals and people - constantly interact with microorganisms, often being not only their repositories, but also their distributors. Microorganisms are the natives of our planet, the first settlers, actively exploring the most incredible natural substrates.

Soil microflora. The number of bacteria in the soil is extremely large - hundreds of millions and billions of individuals per 1 g (Table 5). There are much more of them in soil than in water and air. The total number of bacteria in soils changes. By B. C. Winogradsky, microflora-poor soils contain 200-500 million bacteria per 1 g, medium - up to a billion, rich - two or more billion individuals per 1 g. The number of bacteria depends on the type of soil, their condition, and the depth of the layers (Table 6) .

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

The soil microflora is very diverse. Various physiological groups of bacteria are found here: rotting bacteria, nitrifying bacteria, nitrogen-fixing bacteria, sulfur bacteria, etc. Among them are aerobes and anaerobes, spore and non-spore forms. Microflora is one of the factors in soil formation.

The area of active 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 water bodies. Water is a natural environment where microorganisms develop in large numbers. The bulk of them enters the water from the soil. The factor that determines the number of bacteria in water is the presence of nutrients in it. The cleanest waters are from artesian wells and springs. Open reservoirs and rivers are very rich in bacteria. The largest number of bacteria is found in the surface layers of water, closer to the shore. The water in the suburban area is very polluted due to wastewater. With wastewater, pathogenic microorganisms enter water bodies: brucellosis bacillus, tularemia bacillus, polio virus, foot-and-mouth disease, pathogens of intestinal infections (typhoid bacilli, paratyphoid bacilli, dysentery bacillus, Vibrio cholerae, etc.). Bacteria persist in water for a long time, so it can be a source of infectious diseases. As you move away from the shore and increase in depth, the number of bacteria decreases.

Pure water contains 100-200 bacteria per ml, and polluted water contains 100-300 thousand or more. There are many bacteria in bottom sludge, especially in its surface layer, where bacteria form a film. This film contains a lot of sulfur and iron bacteria, which oxidize hydrogen sulfide to sulfuric acid and thereby prevent fish from dying. There are nitrifying and nitrogen-fixing bacteria. There are more spore-bearing forms in the silt (about 75%), while non-spore-bearing forms predominate in the water (about 97%).

In terms of species composition, the microflora of water is similar to the microflora of soil, but specific bacteria are also found in water (Vas. fluorescens, You. aquatilisand etc.). By destroying various waste that gets into the water, microorganisms gradually carry out the so-called biological purification of water.

Air microflora. The microflora of the air is less numerous than the microflora of soil and water. Bacteria rise into the air with dust, can remain there for some time, and then settle on 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 geographical zone, area, time of year, dust pollution, etc. Each speck of dust is a carrier of microorganisms, so there are a lot of them in enclosed spaces (from 5 to 300 thousand in 1 m 3). Most bacteria are in the air above industrial cities. The air in rural areas is cleaner. The cleanest air is over forests, mountains, and snowy areas. The upper layers of air contain fewer microbes. The air microflora contains many pigmented and spore-bearing bacteria, which are more resistant than others to ultraviolet rays. Very much attention is paid to the microbiological study of air, since infectious diseases (influenza, scarlet fever, diphtheria, tuberculosis, tonsillitis, etc.) can spread through airborne droplets.

Microflora of the human body. The human body, even a completely healthy one, is always a carrier of microflora. When the human body comes into contact with air and soil, various microorganisms, including pathogenic ones (tetanus bacilli, gas gangrene, etc.), settle on clothing and skin. The number of microbes on the skin of one person is 85 million - 1212 million. The exposed parts of the human body are most often contaminated. E. coli and staphylococci are found on the hands. There are over 100 types of microbes in the oral cavity. The mouth with its temperature, humidity, and 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 intestines is very diverse. Each adult excretes about 18 billion bacteria daily in excrement, i.e., more individuals than there are people on the globe.

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

Microorganisms that cause infectious diseases are called pathogenic or pathogenic (Table 7). They are able to penetrate tissue and release substances that destroy the body's protective barrier. Permeability factors

highly active, act in small doses, have enzymatic properties. They enhance the local effect of pathogens, affect connective tissue, and contribute to the development of a general infection. These are the invasive properties of microorganisms.

Substances that inhibit the body’s defenses and enhance the pathogenic effect of pathogens are called aggressins. Pathogenic microorganisms also produce toxins - poisonous waste products. The most powerful poisons secreted by bacteria in environment, are called exotoxins. They are formed by diphtheria and tetanus bacilli, staphylococcus, streptococcus, etc. In most bacteria, toxins are released from cells only after their death and destruction. Such toxins are called endotoxins. They are formed by tuberculosis bacillus, Vibrio cholerae, pneumococci, anthrax pathogen, etc.

There are bacteria that are called opportunistic because under normal conditions they live as saprophytes, but when the resistance of the human or animal body weakens, they can cause serious diseases. For example, E. coli - a common intestinal saprophyte - under unfavorable conditions can cause inflammatory processes in the kidneys, bladder, intestines and other organs.

Louis Pasteur made a great contribution to the fight against infectious diseases of animals and humans.

Pasteur Louis (1822-1895) - French microbiologist and chemist. Founder of microbiology and immunology. He proposed a method of preventive vaccinations with vaccines that have saved and are saving millions of people from infectious diseases.

- Source-

Bogdanova, T.L. Handbook of biology / T.L. Bogdanov [and others]. – K.: Naukova Dumka, 1985.- 585 p.

Post Views: 18

Bacteria are found everywhere: in a drop of even the purest spring water, in grains of soil, in the air, on rocks, in desert sands, on the ocean floor, and even in oil extracted from great depths.

They live in the ice of Antarctica at a temperature of –83 °C and in hot springs, the temperature of which reaches +85-90 °C.

1 g of soil can contain hundreds of millions of bacteria.

They live on plants, fruits, various animals and in humans in the intestines, oral cavity, limbs, and on the surface of the body.

Spread in the air

The spread of most bacteria in the air is associated with constantly changing living conditions of plants, animals and humans, as well as seasonal temperature changes and climatic features. The lowest concentration of microorganisms in nature can be found in mountainous and marine environments, where their reproduction is somewhat difficult. Settlements, on the contrary, become the places where they are most concentrated, especially in the summer. The presence of microorganisms in the air is temporary, since it does not have sufficient nutrients.

In residential premises, the number of bacteria is approximately 1,500 representatives of the microcosm per 1 cubic meter. It is the air environment that becomes a transport for many pathogenic microorganisms that cause respiratory diseases, influenza, tuberculosis, etc. They are released into nature by their carrier and spread quite quickly over considerable distances. Good room ventilation significantly reduces the spread of harmful bacteria.

Spread in soil

The soil is a springboard from which bacteria enter both water and living organisms and air. One gram of it contains up to several billion microorganisms. They are classified as follows:

Putrefactive bacteria of the aerobic and anaerobic type are involved in the process of decomposition of organic matter.
Nitrogen-fixing - help plants absorb nitrogen by processing it from the air.
Nitrifying - work with more complex nitrogen compounds.
Actinomycetes (decompose the most stable substrates), etc.

Pathogenic bacteria enter the soil through the blood and secretions of a sick or dead organism and debris. The causative agents of many intestinal diseases live in the soil for more than a month. Spores of gas gangrene, anthrax and tetanus can survive outside the host for several decades.

The main source of bacteria spread is soil. This is facilitated by:

Availability large quantity nutrients (mineral, organic);
sufficient substrate moisture;
protecting them from direct solar radiation and sudden temperature fluctuations.

Decomposition occurs organic matter- the remains of dead animals and dead plants that fall into the soil. Thanks to this, they are formed inorganic substances, which can later serve as a food base for other organisms, mainly plants, and also simultaneously release carbon dioxide necessary for plant photosynthesis.

Bacteria form a large amount of humus after additional fertilizing the soil with manure, growing perennial and annual herbaceous plants, in which numerous roots die. In the presence of oxygen in the soil, bacteria in a short period of time convert humus into minerals necessary for the nutrition of plants, including cultivated ones. Most bacteria can be found in soils that contain a lot of organic residues (cultivated, fertilized, sufficiently moistened)

Pathogenic (disease-causing) bacteria are also found in the soil. They end up in the ground along with animal corpses, household and industrial waste. They can be pathogens serious illnesses- tetanus, botulism, gas gangrene, etc. Soil is the main source of bacteria entering the air and water.

Distribution in the aquatic environment

Water is a favorable environment for the life of bacteria. Water contamination can amount to up to a million bacteria per ml.

Bacteria enter reservoirs with waste soil water, from the air, etc. The number of bacteria in water depends on its nature. The waters of open reservoirs contain the largest number of bacteria, and artesian waters contain much less because they pass through layers of soil and are partially purified. Water is a source of spread of pathogenic bacteria, especially during epidemics of dysentery, typhoid fever, cholera and other infections. They can be stored in water for several months.

Industrial wastewater and domestic wastewater, as well as rainwater, into which a large number of bacteria enter from the air and from the soil surface, are the main source of bacterial pollution of natural water bodies. Such effluents contain large amounts chemical compounds- chlorides, ammonia, hydrogen sulfide, salts of nitric and phosphoric acids. Treated wastewater and drinking water are disinfected by irradiation with ultraviolet rays and ozonation.

Water may contain pathogens of various diseases, such as:

dysentery;
typhoid fever;
colienteritis.

Once in water, bacteria can remain there for several months, increasing the risk of disease.

Distribution in the human body

This cavity contains:

staphylococci;
streptococci;
micrococci.

Spread of bacteria

MOs make up a significant proportion of living matter on the planet:

0.2% of the total number of species of living organisms

5 thousand species of bacteria have been described - this is 5-6% of all bacteria

In reality - about 5 million types of MOs

(for comparison, there are 1 million known species of insects)

Bacteria live everywhere

Underground kingdom: Caves (several km deep to a level of 100 ºС, limit +113 ºС – thermophiles), Soil, Soil water, Rivers, Air, All living organisms

VBNC– uncultivated forms (dormant) MO – nanobacteria. 15 thousand phantom genotypes of uncultivated forms (nanobacteria) were identified using the PCR method

Biodiversity of bacteria

Various shapes, sizes: 0.2 microns - the smallest, 1 mm - the largest, 1-2 microns - average sizes, 10 -12 g - the weight of one bacterium

Functional role of bacteria

Limited in obtaining energy and substrates.

By ensuring access to nutrients and removal of metabolic products after 1 day. could reach the mass of ZSh (calculation based on carbon).

For the normal existence of the biosphere, constant reproduction of bacteria is necessary.

Living catalysts, high enzymatic activity- decomposers.

Capable of accumulating from the external environment

and transfer to other organisms: N, P, C.

They carry out the cycle of substances in nature.

9. The main differences between prokaryotes and eukaryotes

Genetic material:

Location

P: there is no membrane limiting it from the cytoplasm

E: bounded from the cytoplasm by the nuclear membrane

Form P: circular DNA molecule, E: chromosome

Extrachromosomal DNA P: located in plasmids, E: located in mitochondria

Histones P: there are histone-like proteins, E: there are histones

Type of division P: binary, E: mitosis

Protein synthesis:

Ribosomes P: 70S(50S and 30S), E: 80S (60S and 40S)

Msto synthesis P: ribosomes are freely located in the cytoplasm, E: ribosomes in the composition of sh-EPS

Cell wall:

Structural elements P: peptidoglycan, E: chitin or cellulose

Sterols P: no, E: yes

10. Three sources of energy in bacteria

Based on the type of nutrition, bacteria are divided into two groups: autotrophs and heterotrophs.

Autotrophs:

1. Energy from sunlight (phototrophs - absorb CO2)

2. Energy of chemical bonds (chemotrophs - oxidation of inorganic substances, lithotrophs)

Heterotrophs

3. Energy chemical bonds(organotrophs - breakdown of organic substances)

11. Types of bacterial respiration

Respiration (or biological oxidation) is a complex process that is accompanied by the release of energy necessary for microorganisms to synthesize various organic compounds. Bacteria, like higher animals, use oxygen for respiration. However, L. Pasteur proved the existence of bacteria for which the presence of free oxygen is destructive; the energy necessary for life is obtained by them in the process of fermentation.

All bacteria are divided according to the type of respiration into obligate aerobes, microaerophiles, facultative anaerobes, and obligate anaerobes.

Obligate (strict) aerobes develop in the presence of 20% oxygen in the atmosphere (mycobacterium tuberculosis) and contain enzymes that transfer hydrogen from the oxidizable substrate to atmospheric oxygen.

Microaerophiles need significantly less oxygen, and its high concentration, although it does not kill bacteria, retards their growth (actinoiscetes, brucella, leptospira).

Facultative anaerobes can multiply both in the presence and absence of oxygen (most pathogenic and saprophytic microbes - pathogens of typhoid fever, paratyphoid fever, E. coli).

Obligate anaerobes are bacteria for which the presence of molecular oxygen is destructive (clostridium tetanus, botulism).

Aerobic bacteria oxidize various organic substances (carbohydrates, proteins, fats, alcohols, organic acids, etc.) during respiration.

Respiration in anaerobes occurs by fermentation of the substrate with the formation of a small amount of energy. The processes of decomposition of organic substances in oxygen-free conditions, accompanied by the release of energy, are called fermentation. Depending on the participation of certain mechanisms, the following types of fermentation are distinguished: alcoholic, carried out by yeast, lactic acid, caused by lactic acid bacteria, butyric acid, etc.

The spontaneous combustion of peat, manure, wet hay and cotton is associated with the release of large amounts of heat during the respiration of some microorganisms.

Direction of bacteria movement

When swimming, the flagella gather into a bundle and begin to rotate counterclockwise.

Then the bacterium runs, after which the flagella begin to rotate clockwise.

In this case, the bacterium performs a small somersault.

The direction of movement is random.

The frequency of somersaults and runs will be the same if environmental conditions do not change.

When environmental conditions change, movement parameters change.

Kinesis- a reaction manifested in a change in swimming speed. The trajectory of kinesis is a broken line

Taxis of bacteria

Swimming with a specific purpose - searching for nutrient substrates or avoiding the effects of unfavorable factors.

Purposeful movement - taxi ability.

Swimming in the direction of more favorable conditions is positive taxis.

Avoiding unfavorable conditions is negative taxis.

Taxis is the oriented movement of the MO in the direction of the attractant and away from the repellent.

Types of taxis

1. chemotaxis - response to changes in the concentration of dissolved substances

2. aerotaxis - oxygen

3. osmotaxis - osmolarity

4. phototaxis - illumination

5. thermotaxis - temperatures

6. thigmotaxis – mechanical action

7. galvanotaxis - electric current

8. magnetotaxis – magnetic field