Attention! false theory of infectious diseases in official medicine. why do people actually get sick (from a physical point of view) and what are bacteria? Differences between fungi and plants. Microflora of the human body

Theory for preparation for block No. 4 of the Unified State Examination in biology: with system and diversity of the organic world.

bacteria

bacteria refers to prokaryotic organisms that do not have nuclear membranes, plastids, mitochondria and other membrane organelles. They are characterized by the presence of one circular DNA. The size of the bacteria is quite small 0.15-10 microns. Cells can be divided into three main groups according to their shape: spherical , or cocci , rod-shaped and tortuous . Bacteria, although they belong to prokaryotes, have a rather complex structure.

The structure of bacteria

The bacterial cell is covered with several outer layers. The cell wall is essential for all bacteria and is the main component of the bacterial cell. The cell wall of bacteria gives shape and rigidity and, in addition, performs a number of important functions:

• protects the cell from damage
• involved in metabolism
• many pathogenic bacteria are toxic
• involved in the transport of exotoxins

The main component of the cell wall of bacteria is a polysaccharide murein . Bacteria are divided into two groups based on the structure of the cell wall: gram-positive (stained by Gram when preparing preparations for microscopy) and gram-negative (not stained by this method) bacteria.

Forms of bacteria: 1 - micrococci; 2 - diplococci and tetracocci; 3 - sarcins; 4 - streptococci; 5 - staphylococci; 6, 7 - sticks, or bacilli; 8 - vibrios; 9 - spirilla; 10 - spirochetes

Structure of a bacterial cell: I - capsule; 2 - cell wall; 3 - cytoplasmic membrane;4 - nucleoid; 5 - cytoplasm; 6 - chromatophores; 7 - thylakoids; 8 - mesosome; 9 - ribosomes; 10 - flagella; II - basal body; 12 - drank; 13 - drops of fat

Cell walls of gram-positive (a) and gram-negative (b) bacteria: 1 - membrane; 2 - mucopeptides (murein); 3 - lipoproteins and proteins

Structure diagram cell wall bacteria: 1 - cytoplasmic membrane; 2 - cell wall; 3 - microcapsule; 4 - capsule; 5 - mucous layer

There are three obligatory cellular structures of bacteria:

1. nucleoid
2. ribosomes
3. cytoplasmic membrane (CPM)

The organs of movement of bacteria are flagella, which can be from 1 to 50 or more. Cocci are characterized by the absence of flagella. Bacteria have the ability to directed forms of movement - taxis.

taxis are positive if the movement is directed towards the source of the stimulus, and negative when the movement is directed away from it. The following types of taxis can be distinguished.

Chemotaxis- movement based on difference in concentration chemical substances in the environment.

Aerotaxis- on the difference in oxygen concentrations.

When reacting to light and magnetic field, respectively, phototaxis and magnetotaxis.

An important component in the structure of bacteria are derivatives of the plasma membrane - pili (villi). Pili take part in the fusion of bacteria into large complexes, the attachment of bacteria to the substrate, and the transport of substances.

Bacteria nutrition

By type of nutrition, bacteria are divided into two troupes: autotrophic and heterotrophic. Autotrophic bacteria synthesize organic substances from inorganic ones. Depending on what energy autotrophs use for synthesis organic matter, distinguish between photo- (green and purple sulfur bacteria) and chemosynthetic bacteria (nitrifying, iron bacteria, colorless sulfur bacteria, etc.). Heterotrophic bacteria feed on ready-made organic matter of dead residues (saprotrophs) or living plants, animals and humans (symbionts).

Saprotrophs include decay and fermentation bacteria. The former break down nitrogen-containing compounds, the latter - carbon-containing ones. In both cases, the energy necessary for their life activity is released.

It should be noted the great importance of bacteria in the nitrogen cycle. Only bacteria and cyanobacteria are able to assimilate atmospheric nitrogen. In the future, bacteria carry out the reactions of ammonification (decomposition of proteins from dead organics to amino acids, which are then deaminated to ammonia and other simple nitrogen-containing compounds), nitrification (ammonia is oxidized to nitrites, and nitrites to nitrates), denitrification (nitrates are reduced to gaseous nitrogen).

Breath bacteria

According to the type of respiration, bacteria can be divided into several groups:

• obligate aerobes: grow with free access of oxygen
• facultative anaerobes: develop both with the access of atmospheric oxygen, and in the absence of it
• obligate anaerobes: develop in the complete absence of oxygen in the environment

Reproduction of bacteria

Bacteria reproduce by simple binary cell division. This is preceded by self-doubling (replication) of DNA. Budding occurs as an exception.

Some bacteria have simplified forms of the sexual process. For example, in Escherichia coli, the sexual process resembles conjugation, in which part of the genetic material is transferred from one cell to another upon direct contact. After that, the cells are separated. The number of individuals as a result of the sexual process remains the same, but there is an exchange of hereditary material, i.e., genetic recombination takes place.

Spore formation is characteristic of only a small group of bacteria in which two types of spores are known: endogenous, formed inside the cell, and microcysts, formed from the whole cell. With the formation of spores (microcysts) in a bacterial cell, the amount of free water decreases, enzymatic activity decreases, the protoplast shrinks and becomes covered with a very dense shell. Spores provide the ability to endure adverse conditions. They withstand prolonged drying, heating above 100°C and cooling to almost absolute zero. In the normal state, the bacteria are unstable when dried, exposed to direct sunlight, temperature rises to 65-80 ° C, etc. Under favorable conditions, spores swell and germinate, forming a new vegetative cell of bacteria.

Despite the constant death of bacteria (eating them by protozoa, the action of high and low temperatures, and other adverse factors), these primitive organisms have survived from ancient times due to the ability to rapidly reproduce (a cell can divide every 20-30 minutes), the formation of spores, extremely resistant to environmental factors, and their ubiquitous distribution.

Vaccination

Remembering the heated debates on the issues of evolution and vitalism, we must not forget that people's interest in theoretical biology arose as a result of intensive medical studies, persistent study of functional disorders in the body. No matter how fast biological science developed in theoretical terms, no matter how far it moved away from the daily needs of practice, sooner or later it had to return to the needs of medicine.
The study of theory is by no means something abstract and unjustified, since the introduction of the achievements of theoretical science allows practice to move forward rapidly. And although applied science can develop purely empirically, without theory this development is much slower and more uncertain.
As an example, consider the history of the study of infectious diseases. Until the beginning of the 19th century. doctors, in fact, were completely helpless during the epidemics of plague or other infectious diseases that flared up on our planet from time to time. Smallpox is one of the diseases from which mankind suffered. It was tragic that it spread like a real natural disaster, every third of the sick died, and the survivors remained disfigured for life: faces covered with mountain ash repelled even loved ones.
However, it has been observed that the past illness provided immunity in the next outbreak. Therefore, many considered it more expedient not to avoid the disease, but to endure it, but in a very weak form that would not be life-threatening and would not disfigure the patient. In this case, the person would be guaranteed against repeated diseases. In countries such as Turkey and China, they have long tried to infect people with the contents of pustules from patients with a mild form of smallpox. The risk was great, because sometimes the disease proceeded in a very severe form. At the beginning of the XVIII century. similar vaccinations were carried out in England, but it is difficult to say whether they brought more benefit or harm. Being engaged in practical medical activities, the Englishman Edward Jenner (1749–1823) studied the protective properties of cowpox known in folk medicine: people who have had it become immune to both cowpox and human smallpox. After long and careful observation, on May 14, 1796, Jenner performed the first cowpox inoculation on an eight-year-old boy, using material taken from a woman with cowpox. The vaccination was accompanied by malaise. And two months later, the boy was infected with pus from the pustule of a smallpox patient - and remained healthy. In 1798, after repeating this experience many times, Jenner published the results of his work. He suggested calling the new method vaccination (from the Latin vaccinia - cowpox).
The fear of smallpox was so great that Jenner's method was accepted with enthusiasm, and the resistance of the most conservative was quickly broken. Vaccination spread throughout Europe and the disease receded. In countries with highly developed medicine, doctors no longer felt helpless in the fight against smallpox. In the history of mankind, this was the first case of a quick and radical victory over a dangerous disease.
But only the development of the theory could bring further success. At that time, no one knew the causative agents of infectious diseases; it was not necessary to count on the use of mild forms for vaccination purposes. The task of biologists was to learn how to "make" their own "variants" of milder forms of the disease, but this required knowing much more than was known in Jenner's day.

germ theory of disease

Bacteriology

It is impossible to hope that someday it will be possible to completely isolate people from pathogenic microbes. Sooner or later, a person is at risk of infection. How to treat the patient? Of course, the body has its own means of fighting microbes: after all, as you know, sometimes a patient recovers even without assistance. The outstanding Russian biologist Ilya Ilyich Mechnikov (1845–1916) succeeded in illustrating such an “antibacterial struggle” of the organism. He showed that leukocytes perform the function of protection against pathogenic agents that have entered the body of animals and humans: they leave the blood vessels and rush to the site of infection, where a real battle of white blood cells with bacteria unfolds. Cells that perform a protective role in the body, Mechnikov called phagocytes.
In addition, recovery from many diseases is accompanied by the development of immunity (immunity), although no visible changes are found. This could be quite logically explained by the fact that antibodies are formed in the body of the ill person that have the ability to kill or neutralize the invading microbes. This view also explains the effect of vaccination; in the body of the vaccinated, antibodies are formed that are active against both the cowpox microbe and the smallpox microbe, which is very similar to it. Now victory is assured, but not over the disease itself, but over the microbe that causes it.
Pasteur outlined ways to fight anthrax, a deadly disease that was destroying herds of domestic animals. He found the causative agent of the disease and proved that it belongs to a special type of bacteria. Pasteur heated a preparation of bacteria to destroy their ability to cause disease (pathogenicity). The introduction of weakened (attenuated) bacteria into the body of an animal led to the formation of antibodies capable of resisting the original pathogenic bacteria.
In 1881, Pasteur staged an extremely revealing experiment. For the experiment, a herd of sheep was taken, one part of which was injected with weakened anthrax bacteria, while the other remained unvaccinated. After some time, all the sheep were infected with pathogenic strains. The vaccinated sheep showed no signs of the disease; unvaccinated sheep contracted anthrax and died.
Similar methods were used by Pasteur to fight chicken cholera and, most significantly, with one of the most terrible diseases - rabies (or rabies), transmitted to humans from infected wild or domestic animals.
The success of Pasteur's germ theory revived interest in bacteria. German botanist Ferdinand Julius Kohn (1828–1898) studied under a microscope plant cells. He showed, for example, that the protoplasms of plant and animal cells are essentially identical. In the 60s of the XIX century, he turned to the study of bacteria. Cohn's greatest merit was the establishment of the vegetable nature of bacteria. He was the first to clearly separate bacteria from protozoa and tried to systematize bacteria according to genera and species. This allows us to consider Kohn the founder of modern bacteriology.
Cohn was the first to notice the talent of the young German physician Robert Koch (1843–1910). In 1876, Koch isolated the bacterium that causes anthrax and learned how to grow it. The support of Cohn, who became acquainted with the work of Koch, played an important role in the life of the great microbiologist. Koch cultivated bacteria on a solid medium - gelatin (which was later replaced by agar, extracted from seaweed), and not in a liquid poured into test tubes. This technical improvement has brought many advantages. In a liquid environment, bacteria of different types mix easily, and it is difficult to determine which one causes a particular disease. If the culture is applied as a smear on a solid medium, individual bacteria, dividing many times, form colonies of new cells, strictly fixed in their position. Even if the initial culture consists of a mixture of different types of bacteria, each colony is a pure cell culture, which allows you to accurately determine the type of pathogenic microbes. Koch first poured the medium onto a flat piece of glass, but his assistant Julius Richard Petri (1852–1921) replaced the glass with two flat, shallow glass cups, one of which served as a lid. Petri dishes are still widely used in bacteriology. Using the developed method for isolating pure microbial cultures, Koch and his collaborators isolated the causative agents of many diseases, including tuberculosis (1882).

Insects

Nutrition Factors

During the last third of the last century, the germ theory dominated the minds of most doctors, but there were those who held a different opinion. The German pathologist Virchow - the most famous opponent of Pasteur's theory - believed that diseases were caused by a disorder in the body itself rather than external agents. Virchow's merit was that over several decades of work in the Berlin municipality and national legislatures, he achieved such serious improvements in the field of hygiene as the purification of drinking water and the creation of an effective system for the disinfection of wastewater. Another scientist, Pettenkofer, did a lot in this area. He and Virchow can be considered the founders of modern social hygiene (the study of disease prevention in human society).
Such measures to prevent the spread of epidemics, of course, were no less important than the direct impact on the microbes themselves.
Naturally, the concern for cleanliness, which Hippocrates preached, retained its significance even when the role of microbes became clear to everyone. The advice of Hippocrates regarding the need for a full and varied diet remained in force, and their importance was revealed not only for maintaining health in general, but also as a specific method for preventing certain diseases. The idea that malnutrition could be the cause of disease was considered "old-fashioned" - scientists were obsessed with microbes - but it was supported by fairly strong evidence.
During the Age of Discovery, people spent long months on board ships, eating only those foods that could be well preserved, since the use of artificial cold was not yet known. The terrible scourge of sailors was scurvy. The Scottish physician James Lind (1716-1794) drew attention to the fact that diseases are found not only on board ships, but also in besieged cities and prisons - everywhere where food is monotonous. Perhaps the disease is caused by the absence of any product in the diet? Lind tried to diversify the diet of sailors suffering from scurvy, and soon discovered the healing effect of citrus fruits. The great English navigator James Cook (1728–1779) introduced citrus fruits into the diet of the crew of his Pacific expeditions in the 70s of the 18th century. As a result, only one person died of scurvy. In 1795, during the war with France, the sailors of the British Navy began to be given lemon juice, and not a single case of scurvy was noted.
However, such purely empirical achievements, in the absence of the necessary theoretical justifications, were introduced very slowly. In the 19th century major discoveries in the field of nutrition related to the role of protein. It was found that some proteins, "complete", present in the diet, can support life, others, "inferior", like gelatin, are not able to do this. The explanation came only when the nature of the protein molecule was better known. In 1820, having treated a complex molecule of gelatin with acid, a simple molecule was isolated from it, which was called glycine. Glycine belongs to the class of amino acids. Initially, it was assumed that it serves as a building block for proteins, just as a simple sugar, glucose, is a building block from which starch is built. However, to late XIX in. this theory was found to be untenable. Other simple molecules were obtained from a wide variety of proteins - all of them, differing only in details, belonged to the class of amino acids. The protein molecule turned out to be built not from one, but from a number of amino acids. By 1900, dozens of different amino acid building blocks were known. Now it no longer seemed incredible that proteins differ in the ratio of amino acids they contain. The first scientist to show that a particular protein may not have one or more amino acids that play an essential role in the life of an organism was the English biochemist Frederick Gowland Hopkins (1861–1947). In 1903, he discovered a new amino acid - tryptophan - and developed methods for its detection. Zein, a protein isolated from corn, was negative and therefore did not contain tryptophan. It turned out to be an inferior protein, since, being the only protein in the diet, it did not provide the vital activity of the organism. But even a small addition of tryptophan made it possible to prolong the life of experimental animals.
Subsequent experiments, carried out in the first decade of the 20th century, clearly showed that certain amino acids are synthesized in the mammalian organism from substances normally found in tissues. However, some of the amino acids must be supplied with food. The absence of one or more of these "essential" amino acids makes the protein defective, leading to illness and sometimes death. Thus, the concept of additional nutritional factors was introduced - compounds that cannot be synthesized in the body of animals and humans and must be included in food to ensure normal life.
Strictly speaking, amino acids are not a serious medical problem for nutritionists. Lack of amino acids usually occurs only with artificial and monotonous nutrition. Natural food, even if it is not very rich, provides the body with a sufficient variety of amino acids.
Since a disease such as scurvy is cured by lemon juice, it is reasonable to assume that lemon juice supplies the body with some missing nutritional factor. It is unlikely that it is an amino acid. Indeed, all known biologists of the XIX century. the ingredients of lemon juice, taken together or separately, could not cure scurvy. This food factor had to be a substance needed only in very small quantities and chemically different from the usual components of food.
Finding the mysterious substance was not so difficult. After the development of the doctrine of essential amino acids for life, more subtle nutritional factors were identified that the body needs only in trace amounts, but this did not happen in the process of studying scurvy.

vitamins

In 1886, the Dutch physician Christian Eijkman (1858–1930) was sent to Java to fight beriberi. There were reasons to think that this disease arises as a result of malnutrition. Japanese sailors suffered greatly from beriberi and stopped getting sick only when, in the 80s of the 19th century, milk and meat were introduced into their diet, which consisted almost exclusively of rice and fish. Aikman, however, being captivated by Pasteur's germ theory, was convinced that beriberi was a bacterial disease. He brought chickens with him, hoping to infect them with germs. But all his attempts were unsuccessful. True, in 1896, chickens suddenly fell ill with a disease similar to beriberi. Finding out the circumstances of the disease, the scientist found that just before the outbreak of the disease, chickens were fed polished rice from the hospital food warehouse. When they were transferred to the old food, recovery began. Gradually, Aikman became convinced that this disease could be caused and cured by a simple change in diet.
At first, the scientist did not appreciate the true significance of the data obtained. He suggested that the grains of rice contain some kind of toxin, which is neutralized by something contained in the shell of the grain, and since the shell is removed when the rice is peeled, unneutralized toxins remain in the polished rice. But why hypothesize about the presence of two unknown substances, a toxin and an antitoxin, when it is much easier to assume that there is some kind of nutritional factor needed in negligible amounts? This opinion was shared by Hopkins and the American biochemist Casimir Funk (born in 1884). They suggested that not only beriberi, but also such diseases as scurvy, pellagra and rickets, are explained by the absence of the smallest amounts of certain substances in food.
Still under the impression that these substances belong to the class of amines, Funk proposed in 1912 to call them vitamins (the amines of life). The name has taken root and has been preserved to this day, although it has since become clear that they have nothing to do with amines.
Vitamin hypothesis Hopkins - Funk was fully formulated, and the first third of the XX century. showed that various diseases can be cured by the appointment of a reasonable diet and diet. For example, the American physician Joseph Goldberger (1874–1929) discovered (1915) that the pellagra disease common in the southern states of the United States was by no means of microbial origin. In fact, it was caused by the absence of some vitamin and disappeared as soon as milk was added to the diet of patients. Initially, vitamins were known only that they were able to prevent and treat certain diseases. In 1913, the American biochemist Elmer Vernon McCollum (born in 1879) suggested that vitamins be called letters of the alphabet; this is how vitamins A, B, C and D appeared, and then vitamins E and K were added to them. It turned out that food containing vitamin B actually contains more than one factor that can affect more than one symptom complex. Biologists started talking about vitamins B1, B2, etc.
It turned out that it was the lack of vitamin B1 that caused beriberi, and the lack of vitamin B2 caused pellagra. Lack of vitamin C led to scurvy (the presence of small amounts of vitamin C in citrus juice explains their healing effect, which allowed Lind to cure scurvy), lack of vitamin D to rickets. Lack of vitamin A affected vision and caused night blindness. Vitamin B12 deficiency caused malignant anemia. These are the main diseases caused by vitamin deficiency. With the accumulation of knowledge about vitamins, all these diseases ceased to be a serious medical problem. Since the 30s of the 20th century, vitamins in their pure form began to be isolated and synthesized.

Morphology of bacteria, structure of a prokaryotic cell.

In prokaryotic cells there is no clear boundary between the nucleus and the cytoplasm, there is no nuclear membrane. The DNA in these cells does not form structures similar to eukaryotic chromosomes. Therefore, prokaryotes do not undergo the processes of mitosis and meiosis. Most prokaryotes do not form membrane-bound intracellular organelles. In addition, prokaryotic cells do not have mitochondria and chloroplasts.

bacteria, as a rule, are unicellular organisms, their cell has a rather simple shape, it is a ball or cylinder, sometimes curved. Bacteria reproduce mainly by dividing into two equivalent cells.

spherical bacteria called cocci and can be spherical, ellipsoidal, bean-shaped, and lanceolate.

According to the arrangement of cells relative to each other after division, cocci are divided into several forms. If, after cell division, the cells diverge and are located one by one, then such forms are called monococci. Sometimes cocci, when dividing, form clusters resembling a bunch of grapes. Similar forms are staphylococcus. Cocci remaining in the same plane after division in bound pairs are called diplococci, and generators of different chain lengths - streptococci. Combinations of four cocci that appear after cell division in two mutually perpendicular planes are tetracocci. Some cocci divide in three mutually perpendicular planes, which leads to the formation of peculiar clusters of a cubic shape called sardines.

Most bacteria have cylindrical, or rod-shaped, shape. Rod-shaped bacteria that form spores are called bacilli, and not forming disputes - bacteria.

Rod-shaped bacteria differ in shape, size in length and diameter, the shape of the ends of the cell, as well as in mutual arrangement. They can be cylindrical with straight ends or oval with rounded or pointed ends. Bacteria are also slightly curved, filamentous and branching forms are found (for example, mycobacteria and actinomycetes).

Depending on the mutual arrangement of individual cells after division, rod-shaped bacteria are divided into rods proper (single arrangement of cells), diplobacteria or diplobacilli (paired arrangement of cells), streptobacteria or streptobacilli (form chains of various lengths). Often there are convoluted, or spiral, bacteria. This group includes spirilla (from lat. spira - a curl), having the form of long curved (from 4 to 6 turns) sticks, and vibrios (lat. vibrio - I bend), which are only 1/4 of a spiral coil, similar to a comma .

Filamentous forms of bacteria living in water bodies are known. In addition to those listed, there are multicellular bacteria that carry ethical outgrowths on the surface of the protoplasm cell - prostecs, triangular and star-shaped bacteria, as well as worm-shaped bacteria that have the shape of a closed and open ring.

Bacterial cells are very small. They are measured in micrometers, while fine structure details are measured in nanometers. Cocci usually have a diameter of about 0.5-1.5 microns. The width of rod-shaped (cylindrical) forms of bacteria in most cases ranges from 0.5 to 1 microns, and the length is several micrometers (2-10). Small sticks have a width of 0.2-0.4 and a length of 0.7-1.5 microns. Among bacteria, real giants can also be found, the length of which reaches tens and even hundreds of micrometers. The shapes and sizes of bacteria vary significantly depending on the age of the culture, the composition of the medium and its osmotic properties, temperature, and other factors.

Of the three main forms of bacteria, cocci are the most stable in size, rod-shaped bacteria are more variable, and the length of the cells changes especially significantly.

A bacterial cell placed on the surface of a solid nutrient medium grows and divides, forming a colony of progeny bacteria. After a few hours of growth, the colony already consists of such a large number of cells that it can be seen with the naked eye. Colonies may have a slimy or pasty consistency, in some cases they are pigmented. Sometimes the appearance of the colonies is so characteristic that it makes it possible to identify microorganisms without much difficulty.

Fundamentals of bacterial physiology.

By chemical composition microorganisms differ little from other living cells.

Water is 75-85%, chemicals are dissolved in it.

Dry matter 15-25%, composed of organic and mineral compounds

Nutrition of bacteria. The entry of nutrients into a bacterial cell is carried out in several ways and depends on the concentration of substances, the size of the molecules, the pH of the medium, the permeability of membranes, etc. By type of food microorganisms are divided into:

autotrophs - synthesize all carbon-containing substances from CO2;

heterotrophs - organic matter is used as a carbon source;

saprophytes - feed on organic matter of dead organisms;

Breath bacteria. Respiration, or biological oxidation, is based on redox reactions that take place with the formation of an ATP molecule. In relation to molecular oxygen, bacteria can be divided into three main groups:

obligate aerobes - can grow only in the presence of oxygen;

obligate anaerobes - grow in an environment without oxygen, which is toxic to them;

facultative anaerobes - can grow both with oxygen and without it.

Growth and reproduction of bacteria. Most prokaryotes reproduce by binary fission in half, less often by budding and fragmentation. Bacteria, as a rule, are characterized by a high rate of reproduction. The time of cell division in various bacteria varies quite widely: from 20 minutes in Escherichia coli to 14 hours in Mycobacterium tuberculosis. On dense nutrient media, bacteria form clusters of cells called colonies.

bacterial enzymes. Enzymes play an important role in the metabolism of microorganisms. Distinguish:

endoenzymes - localized in the cytoplasm of cells;

exoenzymes - released into the environment.

Enzymes of aggression destroy tissue and cells, causing a wide distribution of microbes and their toxins in the infected tissue. The biochemical properties of bacteria are determined by the composition of enzymes:

saccharolytic - breakdown of carbohydrates;

proteolytic - the breakdown of proteins,

lipolytic - breakdown of fats,

and are an important diagnostic feature in the identification of microorganisms.

For many pathogenic microorganisms, the optimum temperature is 37°C and pH 7.2-7.4.

Water. Importance of water for bacteria. Water makes up about 80% of the mass of bacteria. The growth and development of bacteria are obligately dependent on the presence of water, since all chemical reactions occurring in living organisms are realized in an aquatic environment. For the normal growth and development of microorganisms, the presence of water in the environment is necessary.

For bacteria, the water content in the substrate should be more than 20%. Water must be in an accessible form: in the liquid phase in the temperature range from 2 to 60 °C; this interval is known as the biokinetic zone. Although water is very stable chemically, its ionization products - H + and OH ions - have a very large effect on the properties of almost all cell components (proteins, nucleic acids, lipids, etc.). Thus, the catalytic activity of enzymes is largely depends on the concentration of H+ and OH ions.

Fermentation is the main source of energy for bacteria.

Fermentation is a metabolic process that produces ATP, and electron donors and acceptors are products formed during fermentation itself.

Fermentation is the process of enzymatic breakdown of organic substances, mainly carbohydrates, proceeding without the use of oxygen. It serves as a source of energy for the life of the body and plays an important role in the circulation of substances and in nature. Some types of fermentation caused by microorganisms (alcohol, lactic, butyric, acetic) are used in the production of ethyl alcohol, glycerin and other technical and food products.

Alcoholic fermentation(carried out by yeast and some types of bacteria), during which pyruvate is broken down into ethanol and carbon dioxide. One molecule of glucose results in two molecules of alcohol (ethanol) and two molecules of carbon dioxide. This type of fermentation is very important in the production of bread, brewing, winemaking and distillation.

lactic acid fermentation, during which pyruvate is reduced to lactic acid, lactic acid bacteria and other organisms carry out. When milk is fermented, lactic acid bacteria convert lactose into lactic acid, turning milk into fermented milk products (yogurt, curdled milk, etc.); lactic acid gives these products a sour taste.

Lactic acid fermentation also occurs in the muscles of animals when the energy demand is higher than that provided by respiration, and the blood does not have time to deliver oxygen.

Burning sensations in the muscles during heavy exercise are correlated with the production of lactic acid and a shift to anaerobic glycolysis, since oxygen is converted to carbon dioxide by aerobic glycolysis faster than the body replenishes oxygen; and soreness in the muscles after exercise is caused by microtrauma of the muscle fibers. The body shifts to this less efficient, but faster, method of producing ATP when oxygen is deficient. The liver then gets rid of the excess lactate, converting it back into an important glycolysis intermediate, pyruvate.

Acetic fermentation carried out by many bacteria. Vinegar (acetic acid) is a direct result of bacterial fermentation. When pickling foods, acetic acid protects food from disease-causing and rotting bacteria.

Butyric fermentation leads to the formation of butyric acid; its causative agents are some anaerobic bacteria of the genus Clostridium.

Reproduction of bacteria.

Some bacteria do not have a sexual process and reproduce only by equal-sized binary transverse fission or budding. For one group of unicellular cyanobacteria, multiple division has been described (a series of fast successive binary divisions, leading to the formation of 4 to 1024 new cells). To ensure the plasticity of the genotype necessary for evolution and adaptation to a changing environment, they have other mechanisms.

When dividing, most gram-positive bacteria and filamentous cyanobacteria synthesize a transverse septum from the periphery to the center with the participation of mesosomes. Gram-negative bacteria divide by constriction: at the site of division, a gradually increasing curvature of the CPM and the cell wall inward is found. When budding, a kidney is formed and grows at one of the poles of the mother cell, the mother cell shows signs of aging and usually cannot produce more than 4 daughter cells. Budding occurs in different groups of bacteria and, presumably, arose several times in the course of evolution.

In other bacteria, in addition to reproduction, a sexual process is observed, but in the most primitive form. The sexual process of bacteria differs from the sexual process of eukaryotes in that bacteria do not form gametes and cell fusion does not occur. The mechanism of recombination in prokaryotes. However, the main event of the sexual process, namely the exchange of genetic material, occurs in this case as well. This is called genetic recombination. Part of the DNA (very rarely all of the DNA) of the donor cell is transferred to the recipient cell, whose DNA is genetically different from that of the donor. In this case, the transferred DNA replaces part of the recipient's DNA. DNA replacement involves enzymes that break down and rejoin DNA strands. This produces DNA that contains the genes of both parental cells. Such DNA is called recombinant. The offspring, or recombinants, show marked diversity in traits caused by gene shifts. Such a variety of characters is very important for evolution and is the main advantage of the sexual process.

There are 3 ways to obtain recombinants. These are, in the order of their discovery, transformation, conjugation, and transduction.

Origin of bacteria.

Bacteria, along with archaea, were among the first living organisms on Earth, appearing about 3.9-3.5 billion years ago. The evolutionary relationships between these groups have not yet been fully studied, there are at least three main hypotheses: N. Pace suggests that they have a common ancestor of protobacteria; Zavarzin considers archaea to be a dead-end branch of eubacteria evolution that has mastered extreme habitats; finally, according to the third hypothesis, archaea are the first living organisms from which bacteria originated.

Eukaryotes arose as a result of symbiogenesis from bacterial cells much later: about 1.9-1.3 billion years ago. The evolution of bacteria is characterized by a pronounced physiological and biochemical bias: with a relative poverty of life forms and a primitive structure, they have mastered almost all currently known biochemical processes. The prokaryotic biosphere already had all the currently existing ways of substance transformation. Eukaryotes, having penetrated into it, changed only the quantitative aspects of their functioning, but not the qualitative ones; at many stages of the cycles of elements, bacteria still retain a monopoly position.

One of the oldest bacteria are cyanobacteria. In the rocks formed 3.5 billion years ago, products of their vital activity - stromatolites - were found, indisputable evidence of the existence of cyanobacteria dates back to 2.2-2.0 billion years ago. Thanks to them, oxygen began to accumulate in the atmosphere, which 2 billion years ago reached concentrations sufficient to start aerobic respiration. The formations characteristic of the obligately aerobic Metallogenium belong to this time.

The appearance of oxygen in the atmosphere (oxygen catastrophe) dealt a serious blow to anaerobic bacteria. They either die out or go to locally preserved anoxic zones. The total species diversity of bacteria at this time is reduced.

It is assumed that due to the lack of a sexual process, the evolution of bacteria follows a completely different mechanism than that of eukaryotes. Constant horizontal gene transfer leads to ambiguities in the picture of evolutionary relationships, evolution proceeds extremely slowly (and, perhaps, with the advent of eukaryotes, it stopped altogether), but under changing conditions, a rapid redistribution of genes between cells occurs with an unchanged common genetic pool.

Systematics of bacteria.

The role of bacteria in nature and in human life.

Bacteria play an important role on Earth. They take an active part in the cycle of substances in nature. All organic compounds and a significant part of inorganic ones undergo significant changes with the help of bacteria. This role in nature is of global importance. Appearing on Earth before all organisms (more than 3.5 billion years ago), they created the living shell of the Earth and continue to actively process living and dead organic matter, involving their metabolic products in the circulation of substances. The cycle of substances in nature is the basis for the existence of life on Earth.

The decay of all plant and animal remains and the formation of humus and humus are also produced mainly by bacteria. Bacteria are a powerful biotic factor in nature.

The soil-forming work of bacteria is of great importance. The first soil on our planet was created by bacteria. However, in our time, the condition and quality of the soil depend on the functioning of soil bacteria. Particularly important for soil fertility are the so-called nitrogen-fixing nodule bacteria-symbionts of leguminous plants. They saturate the soil with valuable nitrogen compounds.

Bacteria purify dirty wastewater by breaking down organic matter and converting it into harmless inorganic matter. This property of bacteria is widely used in the operation of wastewater treatment plants.

In many cases, bacteria can be harmful to humans. So, saprotrophic bacteria spoil food products. To protect products from spoilage, they are subjected to special treatment (boiling, sterilization, freezing, drying, chemical cleaning, etc.). If this is not done, food poisoning may occur.

Among bacteria, there are many disease-causing (pathogenic) species that cause diseases in humans, animals or plants. Typhoid fever is caused by the Salmonella bacterium, and dysentery by the Shigella bacterium. Pathogenic bacteria are carried through the air with droplets of the saliva of a sick person when sneezing, coughing, and even during normal conversation (diphtheria, whooping cough). Some disease-causing bacteria are very resistant to desiccation and persist in the dust for a long time (tuberculosis bacillus). Bacteria of the genus Clostridium live in dust and soil - the causative agents of gas gangrene and tetanus. Some bacterial diseases are transmitted through physical contact with a sick person (venereal disease, leprosy). Often, pathogenic bacteria are transmitted to humans through so-called vectors. For example, flies, crawling through sewage, collect thousands of pathogenic bacteria on their paws, and then leave them on the products consumed by humans.

To begin with, it is worth understanding what immunity is and how it is related to the state of human blood. To do this, we recommend that you carefully read the article “HOW PEOPLE KILL THEIR BLOOD… DO YOU KILL YOUR BLOOD?” (about the connection between blood and immunity, what doctors are silent about):

Next, watch this video, which opens the veil of secrets associated with the infectious theory of diseases. It talks about the Ebola virus and others. You will understand that in order not to get sick with infectious diseases, it is enough to healthy lifestyle life. There is no reason to be afraid to pick up an infection from someone. Even the most terrible viruses and bacteria do not live in a healthy body and a bright soul.

Bacteria are servants given to Man by nature to cleanse our internal environment from toxins.

Primary disease is a natural cleansing of the body.

To clean the internal environment, our body can use microorganisms. He kind of hires microbes to clean up when he can't do it himself. Approximately such a conclusion can be drawn from the hypothesis of Professor A.V. Rusakova, about which A.N. Chuprun spoke about in 1991 in his book “What is a raw food diet and how to become a raw foodist (naturist)”.

The main cause of all our diseases is the slagging of the body. It was noticed that if in this state a person catches some kind of infection, his production of interferon decreases - the defenses seem to be turned off on purpose, allowing the disease to develop. During an illness, our body deliberately turns off the immune system so that bacteria can destroy all the toxins in the body. And we just do not understand the purpose of bacteria on Earth. The bacterium is not interested in our muscles, heart, eyes or brain, but only in our toxins in our tissues. The more waste and toxins we accumulate in our body, the more bacteria we attract.

Another interesting fact is that bacteria will never touch what is still alive. Giant sequoia trees live up to 2,000 years with very little bacteria in their sap. Despite the fact that sequoia roots have been in the ground for literally thousands of years, bacteria do not touch them. However, as soon as the tree dies, the bacteria immediately begin their work of turning the tree back into earth. Bacteria know what lives and what has died, and they are only interested in dead matter.

Can a bacterium cause disease in humans?
Yes and no.
Yes, if the human body is filled with toxins.
Not if the body is clean inside.
Therefore, those who eat mainly boiled food get sick easily. If you don't want to get sick, keep your intestines clean.

The process of purification by bacteria in humans can be schematically represented as follows.

Alien residues from distorted cooked food molecules that have accumulated in the body are a breeding ground for some microorganisms and, in addition, they are a significant hindrance to the functioning of the immune system. With an additional weakening of local immunity, for example, in the case of cooling, or with a massive viral infection, favorable conditions are created in some place of the human body for the reproduction of some of the ubiquitous microorganisms.

A focus of inflammation is formed, where microbes intensively process the accumulated foreign residues into other substances that our body can already remove on its own, for example, in the form of secretions during a runny nose, cough, skin manifestations, etc. After the completion of this work, the immune system, in an already cleansed organism, restores its activity and suppresses the microflora that has expired. This is the primary natural protective and adaptive reaction of a normal organism to a polluted state of the internal environment.

This cleansing reaction is called the word "disease", since its manifestations are unpleasant for a person and usually painful. Specific names for such inflammatory diseases are given, as already mentioned, by the name of the place in which the focus of inflammation was formed. Microorganisms there can also be different, but the essence of these processes is the same: the internal environment of the body is cleaned.

These diseases share many common symptoms. Usually the temperature rises, soreness of the inflamed area of ​​the body occurs, appetite decreases, weakness appears, later skin phenomena or other excretory processes may occur - runny nose, cough .... All these symptoms do not mean the defeat of the organism, but, on the contrary, its rational wise behavior, which ensures its victorious completion of purification. For the body, such a procedure is also “not honey”, but it chooses the lesser evil. It is more important for him to get rid of pollution quickly and with minimal damage. Nature is wise, she knows her business well.

When, for example, antibiotics or other medicines are used in these harmless primary cleansing diseases, the unpleasant symptoms decrease, the runny nose or cough stops, the temperature decreases and the situation seems to have improved. Outwardly, it looks like helping a person, like restoring health, so until now, in such cases, this is traditionally done. But this is self-deception, or rather, an erroneous understanding of the situation. This is harmful, because as a result of such an intervention in the work of the body, the purification process stops or becomes a protracted chronic form. But the main task - to return the natural purity of the internal environment - remains unfulfilled.

Moreover, each such "treatment" dulls the body's sensitivity to pollution and deprives it of its primary cleansing reactions. Such an organism is in completely abnormal conditions, it is doomed to exist at a high level of internal pollution, and this grossly distorts its life processes and further leads to more severe disorders, to the emergence of secondary and tertiary diseases.

In such “healed” people, pathological processes gradually develop, which, due to differences in hereditary and acquired properties, manifest themselves in the form of a variety of diseases: allergies, diabetes, hypertension, heart failure, etc., and in some “for no apparent reason” unexpected heart attack or stroke. There is an opinion that cancer also occurs due to many disorders in the body, caused by high pollution of the internal environment.

The body's ability to maintain a clean internal environment can serve as one of the generalized indicators of human health. When medicine will be able to reliably measure the "slagging" of the body and its sensitivity to various types of pollution, i.e. ability to self-cleaning, then it will be possible to approach the direct measurement of the parameter that Academician N.M. Amosov called "the amount of health." Then it will be possible to objectively assess the results of the impact on the body of various medicines and reasonably decide on the appropriateness of their use.

Unfortunately, doctors who use medications do not always care about long-term consequences. It is more important for them to get a momentary reduction in unpleasant symptoms, to get a “treatment effect”. The position of physicians can be understood: they usually have to deal with patients whose organism is so damaged by repeated use of drugs and so heavily polluted that its natural cleansing reactions proceed in a distorted, severe form. Doctors are forced, reinsured, to use medicines again, despite the fact that in most cases such treatment distorts the body's natural defense reactions even more, reduces its reactivity and reduces the “amount of health”.

IMPORTANT! HOW FLOUR AFFECTS IMMUNITY? WHY IS BREAD HARMFUL!

Another helpful video HOW TO RESTORE THE INTESTINAL MICROFLORA AND IMMUNE:

IMPORTANT INFORMATION!BASIC ALGORITHM AND METHODS OF TREATMENT OF ANY DISEASES:

To better understand the causes and mechanisms of the occurrence of diseases, be sure to study the articles:

* BLOOD OXIDATION LEADS TO DISEASE OF THE ORGANISM! WHY BLOOD ACIDIFICATION IS A HEALTH THREAT. ACID-BALANCE BALANCE OF THE BODY (acid-base balance) - THE PHYSICAL BASIS OF HUMAN HEALTH!

* ATTENTION! THE RESULTS OF THE LARGEST LONG-TERM NUTRITION STUDIES PROVE A DIRECT LINK BETWEEN DEADLY DISEASES AND THE CONSUMPTION OF "FOOD" OF ANIMAL ORIGIN (any meat and dairy products)!

* HOW CHRONIC DISEASES APPEAR. HOW DIFFERENT ORGANIS IN THE ORGANISM ARE INTERRELATED (what influences what). How to find the cause of your diseases. Video compilation A.T. Ogulov:

* MUSCLE-FREE NUTRITION - THE WAY TO HEALTH AND LONGEVITY!

IMPORTANT ARTICLE! DON'T LET THE LYMPH STAY! Licorice is the best lymphostimulator, a plant created to cleanse and renew the lymphatic system!

HEALING COLDS AND FLU BY EFFECTIVE NATURAL METHODS! AND PREVENTION, HOW TO STAY HEALTHY!

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 adaptable different conditions 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 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, but energy as an energy source for such synthesis. 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 action of sunlight, during 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 to simple ones, which are again used 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 are actively involved 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 exploded volcanoes. 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 geographical area, terrain, 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 different type. 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.