Bacteria are formed. Growth and reproduction of bacteria

True, bacteria), microorganisms with a prokaryotic type of cell structure: their genetic apparatus is not enclosed in a cell nucleus isolated by a membrane.

Sizes and shapes of cells. Most bacteria are single-celled organisms with a size of 0.2-10.0 microns. Among the bacteria, there are also “dwarfs”, the so-called nanobacteria (about 0.05 microns), and “giants”, for example, bacteria of the genera Achromatium and Macromonas (length up to 100 microns), an inhabitant of the intestines of the surgeon fish Epulopiscium fishelsoni (length up to 600 microns) and Thiomargarita namibiensis isolated from coastal sea waters of Namibia and Chile (up to 800 µm). Most often, the bacterial cell has a rod-shaped, spherical (cocci) or convoluted (vibrios, spirilla and spirochetes) shape. Species with triangular, square, stellate and flat (plate-shaped) cells have been found. Some bacteria contain cytoplasmic projections called prosteks. Bacteria can be single, form pairs, short and long chains, clusters, form packets of 4, 8 or more cells (sarcinae), rosettes, networks and mycelium (actinomycetes). Multicellular forms are also known, forming straight and branching trichomes (microcolonies). Both motile and nonmotile bacteria are found. The former most often move with the help of flagella, sometimes by sliding cells (myxobacteria, cyanobacteria, spirochetes, etc.). A “jumping” movement is also known, the nature of which is not clear. For mobile forms, the phenomena of active movement in response to the action of physical or chemical factors are described.

Chemical composition and structure of cells. A bacterial cell is usually 70-80% water. In the dry residue, protein accounts for 50%, cell wall components 10-20%, RNA 10-20%, DNA 3-4% and lipids 10%. On average, the amount of carbon is 50%, oxygen 20%, nitrogen 14%, hydrogen 8%, phosphorus 3%, sulfur and potassium 1% each, calcium and magnesium 0.5% each and iron 0.2%.

With few exceptions (mycoplasmas), bacterial cells are surrounded by a cell wall, which determines the shape of the bacterium and performs mechanical and important physiological functions. Its main component is the complex biopolymer murein (peptidoglycan). Depending on the characteristics of the composition and structure of the cell wall, bacteria behave differently when stained according to the method of H. C. Gram (the Danish scientist who proposed the staining method), which served as the basis for dividing bacteria into gram-positive, gram-negative and those lacking a cell wall (for example , mycoplasma). The former are distinguished by a high (up to 40 times) murein content and a thick wall; in gram-negatives it is significantly thinner and covered on the outside with an outer membrane consisting of proteins, phospholipids and lipopolysaccharides and, apparently, involved in the transport of substances. Many bacteria have villi (fimbriae, pili) and flagella on their surface that enable their movement. Often the cell walls of bacteria are surrounded by mucous capsules of varying thickness, formed mainly by polysaccharides (sometimes glycoproteins or polypeptides). In a number of bacteria, so-called S-layers (from English surface) were also found, lining the outer surface of the cell membrane with evenly packed protein structures of regular shape.

The cytoplasmic membrane, which separates the cytoplasm from the cell wall, serves as the osmotic barrier of the cell and regulates the transport of substances; the processes of respiration, nitrogen fixation, chemosynthesis, etc. are carried out in it. It often forms invaginations - mesosomes. The biosynthesis of the cell wall, sporulation, etc. are also associated with the cytoplasmic membrane and its derivatives. Flagella and genomic DNA are attached to it.

The bacterial cell is organized quite simply. In the cytoplasm of many bacteria there are inclusions represented by various types of bubbles (vesicles) formed as a result of invagination of the cytoplasmic membrane. Phototrophic, nitrifying and methane-oxidizing bacteria are characterized by a developed network of cytoplasmic membranes in the form of undivided vesicles, reminiscent of the grana of eukaryotic chloroplasts. The cells of some water-dwelling bacteria contain gas vacuoles (aerosomes) that act as density regulators; In many bacteria, inclusions of reserve substances are found - polysaccharides, poly-β-hydroxybutyrate, polyphosphates, sulfur, etc. Ribosomes are also present in the cytoplasm (from 5 to 50 thousand). Some bacteria (for example, many cyanobacteria) have carboxysomes - bodies that contain an enzyme involved in CO 2 fixation. The so-called parasporal bodies of some spore-forming bacteria contain a toxin that kills insect larvae.

The bacterial genome (nucleoid) is represented by a circular DNA molecule, which is often called the bacterial chromosome. The bacterial genome is characterized by the combination of many functionally related genes into so-called operons. In addition, the cell may contain extrachromosomal genetic elements - plasmid DNA, which carry several genes useful for bacteria (including antibiotic resistance genes). It can exist autonomously or be temporarily included in the chromosome. But sometimes, as a result of mutations, this DNA loses its ability to leave the chromosome and becomes a permanent component of the genome. The appearance of new genes can also be caused by genetic transfer as a result of unidirectional transfer of DNA from a donor cell to a recipient cell (an analogue of the sexual process). Such transfer can occur through direct contact of two cells (conjugation), with the participation of bacteriophages (transduction), or by the entry of genes into the cell from the external environment without intercellular contact. All this is of great importance for the microevolution of bacteria and their acquisition of new properties.

Reproduction. Most bacteria reproduce by fission in two, less often by budding, and some (for example, actinomycetes) - with the help of exospores or fragments of mycelium. There is a known method of multiple division (with the formation of small reproductive cells-baeocytes in a number of cyanobacteria). Multicellular prokaryotes can reproduce by detaching one or more cells from the trichomes. Some bacteria are characterized by a complex development cycle, during which the morphology of cells can change and resting forms can be formed: cysts, endospores, akinetes. Myxobacteria are capable of forming fruiting bodies, often of bizarre configurations and colors.

A distinctive feature of bacteria is their ability to reproduce quickly. For example, the doubling time of Escherichia coli cells is 20 minutes. It is estimated that the progeny of one cell, in the case of unlimited growth, in just 48 hours would exceed the mass of the Earth by 150 times.

Living conditions. Bacteria have adapted to different living conditions. They can develop in a temperature range from -5 (and below) to 113 °C. Among them are: psychrophiles, growing at temperatures below 20 ° C (for Bacillus psichrophilus, for example, the maximum growth temperature is -10 ° C), mesophiles (optimum growth at 20-40 ° C), thermophiles (50-60 ° C), extreme thermophiles (70 °C) and hyperthermophiles (80 °C and above). Spores of certain types of bacteria can withstand short-term heating to 160-180 °C and long-term cooling to -196 °C and below. Some bacteria are extremely resistant to ionizing radiation and even live in the cooling water of nuclear reactors (Deinococcus radiodurans). A number of bacteria (barophiles, or piezophiles) tolerate hydrostatic pressure up to 101 thousand kPa, and certain species do not grow at pressures below 50 thousand kPa. At the same time, there are bacteria that cannot withstand even a slight increase in atmospheric pressure. Most types of bacteria do not develop if the concentration of salts (NaCl) in the medium exceeds 0.5 mol/l. Optimal conditions for the development of moderate and extreme halophiles are observed in environments with NaCl concentrations of 10 and 30%, respectively; they can grow even in saturated salt solutions.

As a rule, bacteria prefer neutral environmental conditions (pH about 7.0), although there are both extreme acidiphiles, capable of growth at pH 0.1-0.5, and alkaliphiles, developing at pH up to 13.0.

The vast majority of bacteria studied are aerobes. Some of them can grow only at low concentrations of O 2 - up to 1.0-5.0% (microaerophiles). Facultative anaerobes grow both in the presence of O 2 and in its absence; they are able to switch metabolism from aerobic respiration to fermentation or anaerobic respiration (enterobacteria). The growth of aerotolerant anaerobes is not inhibited in the presence of a small amount of O 2, because they do not use it in the process of life (for example, lactic acid bacteria). For strict anaerobes, even traces of O 2 in the habitat are destructive.

Many bacteria survive unfavorable environmental conditions, forming dormant forms.

Most bacteria that utilize nitrogen compounds, as a rule, use its reduced forms (most often ammonium salts), some require ready-made amino acids, while others also assimilate its oxidized forms (mainly nitrates). A significant number of free-living and symbiotic bacteria are capable of fixing molecular nitrogen (see the article Nitrogen fixation). Phosphorus, which is part of nucleic acids and other cell compounds, is obtained by bacteria mainly from phosphates. The source of sulfur necessary for the biosynthesis of amino acids and some enzyme cofactors is most often sulfates; Some types of bacteria require reduced sulfur compounds.

Taxonomy. There is no officially accepted classification of bacteria. Initially, an artificial classification was used for these purposes, based on the similarity of their morphological and physiological characteristics. A more advanced phylogenetic (natural) classification unites related forms based on their common origin. This approach became possible after the choice of the 16S rRNA gene as a universal marker and the advent of methods for determining and comparing nucleotide sequences. The gene encoding 16S rRNA (part of the small subunit of the prokaryotic ribosome) is present in all prokaryotes and is characterized by a high degree of conservation of the nucleotide sequence and functional stability.

The most commonly used is the classification published in the periodical of the determinant Bergi (Bergi); see also the website on the Internet - http://141. 150.157.117:8080/prokPUB/index.htm. According to one of the existing systems of organisms, bacteria, together with archaea, constitute the kingdom of prokaryotes. Many researchers consider them as a domain (or superkingdom), along with the domains (or superkingdoms) of archaea and eukaryotes. Within the domain, the largest taxa of bacteria are the phyla: Proteobacteria, including 5 classes and 28 orders; Actinobacteria (5 classes and 14 orders) and Firmicutes (3 classes and 9 orders). In addition, taxonomic categories of lower rank are distinguished: families, genera, species and subspecies.

According to modern concepts, bacterial strains in which the nucleotide sequences in the genes encoding 16S rRNA coincide by more than 97%, and the level of homology of nucleotide sequences in the genome exceeds 70%, are classified as one species. No more than 5,000 species of bacteria have been described, which represent only a small part of those inhabiting our planet.

Bacteria actively participate in biogeochemical cycles on our planet (including the cycle of most chemical elements). The modern geochemical activity of bacteria is also global in nature. For example, out of 4.3 10 10 tons (gigatons) of organic carbon fixed during photosynthesis in the World Ocean, about 4.0 10 10 tons are mineralized in the water column, and 70-75% of them are bacteria and some other microorganisms , and the total production of reduced sulfur in ocean sediments reaches 4.92·10 8 tons per year, which is almost three times the total annual production of all types of sulfur-containing raw materials used by humanity. The bulk of the greenhouse gas methane entering the atmosphere is produced by bacteria (methanogens). Bacteria are a key factor in soil formation, oxidation zones of sulfide and sulfur deposits, the formation of iron and manganese sedimentary rocks, etc.

Some bacteria cause serious diseases in humans, animals and plants. They often cause damage to agricultural products, destruction of underground parts of buildings, pipelines, metal structures of mines, underwater structures, etc. Studying the characteristics of the life activity of these bacteria makes it possible to develop effective ways to protect against the damage they cause. At the same time, the positive role of bacteria for humans cannot be overestimated. With the help of bacteria, wine, dairy products, starter cultures and other products, acetone and butanol, acetic and citric acids, some vitamins, a number of enzymes, antibiotics and carotenoids are produced; bacteria are involved in the transformation of steroid hormones and other compounds. They are used to produce protein (including enzymes) and a number of amino acids. The use of bacteria to process agricultural waste into biogas or ethanol makes it possible to create fundamentally new renewable energy resources. Bacteria are used to extract metals (including gold), increase oil recovery (see articles Bacterial leaching, Biogeotechnology). Thanks to bacteria and plasmids, the development of genetic engineering became possible. The study of bacteria played a huge role in the development of many areas of biology, medicine, agronomy, etc. Their importance in the development of genetics is great, because they have become a classic object for studying the nature of genes and the mechanisms of their action. The establishment of metabolic pathways for various compounds, etc., is associated with bacteria.

The potential of bacteria is practically inexhaustible. Deepening knowledge about their life activities opens up new directions for the effective use of bacteria in biotechnology and other industries.

Lit.: Schlegel G. General microbiology. M., 1987; The Prokaryotes: Electronic release 3.0-3.17-. N. Y., 1999-2004-; Zavarzin G. A., Kolotilova N. N. Introduction to natural history microbiology. M., 2001; Madigan M. T., Martinko J., Parker J. Brock biology of microorganisms. 10th ed. Upper Saddle River, 2003; Ecology of microorganisms. M., 2004.

Most people associate the word “bacteria” with something unpleasant and a threat to health. At best, fermented milk products come to mind. At worst - dysbacteriosis, plague, dysentery and other troubles. But bacteria are everywhere, they are good and bad. What can microorganisms hide?

What are bacteria

Man and bacteria

The appearance of bacteria in the body

Beneficial bacteria are: lactic acid bacteria, bifidobacteria, E. coli, streptomycents, mycorrhizae, cyanobacteria.

They all play an important role in human life. Some of them prevent the occurrence of infections, others are used in the production of medicines, and others maintain balance in the ecosystem of our planet.

Types of harmful bacteria

Harmful bacteria can cause a number of serious illnesses in humans. For example, diphtheria, anthrax, sore throat, plague and many others. They are easily transmitted from an infected person through air, food, or touch. It is the harmful bacteria, the names of which will be given below, that spoil food. They give off an unpleasant odor, rot and decompose, and cause diseases.

Bacteria can be gram-positive, gram-negative, rod-shaped.

Names of harmful bacteria

Table. Harmful bacteria for humans. Titles

Titles	Habitat	Harm
Mycobacteria	food, water	tuberculosis, leprosy, ulcer
Tetanus bacillus	soil, skin, digestive tract	tetanus, muscle spasms, respiratory failure
Plague stick (considered by experts as a biological weapon)	only in humans, rodents and mammals	bubonic plague, pneumonia, skin infections
Helicobacter pylori	human gastric mucosa	gastritis, peptic ulcer, produces cytoxins, ammonia
Anthrax bacillus	the soil	anthrax
Botulism stick	food, contaminated dishes	poisoning

Harmful bacteria can stay in the body for a long time and absorb beneficial substances from it. However, they can cause an infectious disease.

The most dangerous bacteria

One of the most resistant bacteria is methicillin. It is better known as Staphylococcus aureus (Staphylococcus aureus). This microorganism can cause not one, but several infectious diseases. Some types of these bacteria are resistant to powerful antibiotics and antiseptics. Strains of this bacterium can live in the upper respiratory tract, open wounds and urinary tract of every third inhabitant of the Earth. For a person with a strong immune system, this does not pose a danger.

Harmful bacteria to humans are also pathogens called Salmonella typhi. They are the causative agents of acute intestinal infections and typhoid fever. These types of bacteria, harmful to humans, are dangerous because they produce toxic substances that are extremely dangerous to life. As the disease progresses, intoxication of the body occurs, very high fever, rashes on the body, and the liver and spleen enlarge. The bacterium is very resistant to various external influences. Lives well in water, on vegetables, fruits and reproduces well in milk products.

Clostridium tetan is also one of the most dangerous bacteria. It produces a poison called tetanus exotoxin. People who become infected with this pathogen experience terrible pain, seizures and die very hard. The disease is called tetanus. Despite the fact that the vaccine was created back in 1890, 60 thousand people die from it every year on Earth.

And another bacterium that can lead to human death is Mycobacterium tuberculosis. It causes tuberculosis, which is drug-resistant. If you do not seek help in a timely manner, a person may die.

Measures to prevent the spread of infections

Harmful bacteria and the names of microorganisms are studied by doctors of all disciplines from their student days. Healthcare annually seeks new methods to prevent the spread of life-threatening infections. If you follow preventive measures, you will not have to waste energy on finding new ways to combat such diseases.

To do this, it is necessary to timely identify the source of the infection, determine the circle of sick people and possible victims. It is imperative to isolate those who are infected and disinfect the source of infection.

The second stage is the destruction of pathways through which harmful bacteria can be transmitted. For this purpose, appropriate propaganda is carried out among the population.

Food facilities, reservoirs, and food storage warehouses are taken under control.

Every person can resist harmful bacteria by strengthening their immunity in every possible way. A healthy lifestyle, observing basic hygiene rules, protecting yourself during sexual contact, using sterile disposable medical instruments and equipment, completely limiting communication with people in quarantine. If you enter an epidemiological area or a source of infection, you must strictly comply with all the requirements of sanitary and epidemiological services. A number of infections are equated in their effects to bacteriological weapons.

What types of bacteria are there: names and types

The most ancient living organism on our planet. Not only have its members survived for billions of years, but they are also powerful enough to wipe out every other species on Earth. In this article we will look at what types of bacteria there are.

Let's talk about their structure, functions, and also name some useful and harmful types.

Discovery of bacteria

Types of bacteria in urine

Structure

Metabolism

Reproduction

Place in the world

Previously, we figured out what bacteria are. Now it’s worth talking about what role they play in nature.

Researchers say that bacteria are the first living organisms to appear on our planet. There are both aerobic and anaerobic varieties. Therefore, single-celled creatures are able to survive various disasters that occur on the Earth.

The undoubted benefit of bacteria lies in the assimilation of atmospheric nitrogen. They are involved in the formation of soil fertility and the destruction of the remains of dead representatives of flora and fauna. In addition, microorganisms participate in the creation of minerals and are responsible for maintaining oxygen and carbon dioxide reserves in the atmosphere of our planet.

The total biomass of prokaryotes is about five hundred billion tons. It stores more than eighty percent of phosphorus, nitrogen and carbon.

However, on Earth there are not only beneficial, but also pathogenic species of bacteria. They cause many deadly diseases. For example, among these are tuberculosis, leprosy, plague, syphilis, anthrax and many others. But even those that are conditionally safe for human life can become a threat if the level of immunity decreases.

There are also bacteria that infect animals, birds, fish and plants. Thus, microorganisms are not only in symbiosis with more developed beings. Next we will talk about what pathogenic bacteria there are, as well as about beneficial representatives of this type of microorganism.

Bacteria and humans

Even at school they teach what bacteria are. Grade 3 knows all kinds of cyanobacteria and other single-celled organisms, their structure and reproduction. Now we will talk about the practical side of the issue.

Half a century ago, no one even thought about such an issue as the state of microflora in the intestines. Everything was OK. Eating more natural and healthier, less hormones and antibiotics, less chemical emissions into the environment.

Today, in conditions of poor nutrition, stress, and an overabundance of antibiotics, dysbiosis and related problems are taking leading positions. How do doctors propose to deal with this?

One of the main answers is the use of probiotics. This is a special complex that repopulates the human intestines with beneficial bacteria.

Such an intervention can help with such unpleasant issues as food allergies, lactose intolerance, gastrointestinal disorders and other ailments.

Let's now touch on what beneficial bacteria there are, and also learn about their effect on health.

Three types of microorganisms have been studied in the most detail and are widely used to have a positive effect on the human body: acidophilus, Bulgarian bacillus and bifidobacteria.

The first two are designed to stimulate the immune system, as well as reduce the growth of some harmful microorganisms such as yeast, E. coli, and so on. Bifidobacteria are responsible for digesting lactose, producing certain vitamins and lowering cholesterol.

Harmful bacteria

Earlier we talked about what types of bacteria there are. The types and names of the most common beneficial microorganisms were announced above. Next we will talk about the “single-cell enemies” of humans.

There are some that are harmful only to humans, while others are deadly for animals or plants. People have learned to use the latter, in particular, to destroy weeds and annoying insects.

Before delving into what harmful bacteria are, it’s worth determining how they spread. And there are a lot of them. There are microorganisms that are transmitted through contaminated and unwashed food, by airborne droplets and contact, through water, soil or through insect bites.

The worst thing is that just one cell, once in the favorable environment of the human body, is capable of multiplying to several million bacteria within just a few hours.

If we talk about what types of bacteria there are, the names of pathogenic and beneficial ones are difficult for a layman to distinguish. In science, Latin terms are used to refer to microorganisms. In common parlance, abstruse words are replaced by concepts - “Escherichia coli”, “pathogens” of cholera, whooping cough, tuberculosis and others.

Preventive measures to prevent the disease are of three types. These are vaccinations and vaccinations, interruption of transmission routes (gauze bandages, gloves) and quarantine.

Where do bacteria in urine come from?

Which bacteria are beneficial?

Bacteria are everywhere - we have heard a similar slogan since infancy. We are trying with all our might to resist these microorganisms by sterilizing the environment. Is it necessary to do this?

There are bacteria that are protectors and helpers of both humans and the environment. These living microorganisms cover humans and nature with millions of colonies. They are active participants in all processes occurring on the planet and directly in the body of any living creature. Their goal is to be responsible for the correct flow of life processes and to be everywhere where one cannot do without them.

The vast world of bacteria

According to studies conducted regularly by scientists, the human body contains more than two and a half kilograms of various bacteria.

All bacteria are involved in life processes. For example, some help in the digestion of food, others are active assistants in the production of vitamins, and others act as protectors against harmful viruses and microorganisms.

One of the very useful living creatures present in the external environment is a nitrogen-fixing bacterium, which is found in the root nodules of plants that release nitrogen into the atmosphere necessary for human respiration.

There is another group of microorganisms that are associated with the digestion of waste organic compounds, which helps maintain soil fertility at the proper level. This includes nitrogen-fixing microbes.

Medicinal and food bacteria

Other microorganisms take an active part in the process of producing antibiotics - these are streptomycin and tetracycline. These bacteria are called Streptomyces and are soil bacteria that are used in the manufacture of not only antibiotics, but also industrial and food products.

For these food industries, the bacterium Lactobacillis is widely used, which is involved in fermentation processes. Therefore, it is in demand in the production of yogurt, beer, cheese, and wine.

All these representatives of microorganisms-helpers live according to their own strict rules. Violation of their balance leads to the most negative phenomena. First of all, dysbacteriosis is caused in the human body, the consequences of which are sometimes irreversible.

Secondly, all human restorative functions associated with internal or external organs are much more difficult when there is an imbalance of beneficial bacteria. The same applies to the group that is involved in food production.

The bacterial organism is represented by one single cell. The forms of bacteria are varied. The structure of bacteria differs from the structure of animal and plant cells.

The cell lacks a nucleus, mitochondria and plastids. The carrier of hereditary information DNA is located in the center of the cell in a folded form. Microorganisms that do not have a true nucleus are classified as prokaryotes. All bacteria are prokaryotes.

It is estimated that there are over a million species of these amazing organisms on earth. To date, about 10 thousand species have been described.

A bacterial cell has a wall, a cytoplasmic membrane, cytoplasm with inclusions and a nucleotide. Of the additional structures, some cells have flagella, pili (a mechanism for adhesion and retention on the surface) and a capsule. Under unfavorable conditions, some bacterial cells are capable of forming spores. The average size of bacteria is 0.5-5 microns.

External structure of bacteria

Rice. 1. The structure of a bacterial cell.

Cell wall

The cell wall of a bacterial cell is its protection and support. It gives the microorganism its own specific shape.
The cell wall is permeable. Nutrients pass inward and metabolic products pass through it.
Some types of bacteria produce special mucus that resembles a capsule that protects them from drying out.
Some cells have flagella (one or more) or villi that help them move.
Bacterial cells that appear pink when Gram stained ( gram-negative), the cell wall is thinner and multilayered. Enzymes that help break down nutrients are released.
Bacteria that appear violet on Gram staining ( gram-positive), the cell wall is thick. Nutrients that enter the cell are broken down in the periplasmic space (the space between the cell wall and the cytoplasmic membrane) by hydrolytic enzymes.
There are numerous receptors on the surface of the cell wall. Cell killers - phages, colicins and chemical compounds - are attached to them.
Wall lipoproteins in some types of bacteria are antigens called toxins.
With long-term treatment with antibiotics and for a number of other reasons, some cells lose their membranes, but retain the ability to reproduce. They acquire a rounded shape - L-shape and can persist in the human body for a long time (cocci or tuberculosis bacilli). Unstable L-forms have the ability to return to their original form (reversion).

Rice. 2. The photo shows the structure of the bacterial wall of gram-negative bacteria (left) and gram-positive bacteria (right).

Capsule

Under unfavorable environmental conditions, bacteria form a capsule. The microcapsule adheres tightly to the wall. It can only be seen in an electron microscope. The macrocapsule is often formed by pathogenic microbes (pneumococci). In Klebsiella pneumoniae, the macrocapsule is always found.

Rice. 3. In the photo is pneumococcus. Arrows indicate the capsule (electronogram of an ultrathin section).

Capsule-like shell

The capsule-like shell is a formation loosely associated with the cell wall. Thanks to bacterial enzymes, the capsule-like shell is covered with carbohydrates (exopolysaccharides) from the external environment, which ensures the adhesion of bacteria to different surfaces, even completely smooth ones.

For example, streptococci, when entering the human body, are able to stick to teeth and heart valves.

The functions of the capsule are varied:

protection from aggressive environmental conditions,
ensuring adhesion (sticking) to human cells,
Possessing antigenic properties, the capsule has a toxic effect when introduced into a living organism.

Rice. 4. Streptococci are capable of sticking to tooth enamel and, together with other microbes, cause caries.

Rice. 5. The photo shows damage to the mitral valve due to rheumatism. The cause is streptococci.

Flagella

Some bacterial cells have flagella (one or more) or villi that help them move. The flagella contain the contractile protein flagellin.
The number of flagella can be different - one, a bundle of flagella, flagella at different ends of the cell or over the entire surface.
Movement (random or rotational) is carried out as a result of the rotational movement of the flagella.
The antigenic properties of flagella have a toxic effect in disease.
Bacteria that do not have flagella, when covered with mucus, are able to glide. Aquatic bacteria contain 40-60 vacuoles filled with nitrogen.

They provide diving and ascent. In the soil, the bacterial cell moves through soil channels.

Rice. 6. Scheme of attachment and operation of the flagellum.

Rice. 7. The photo shows different types of flagellated microbes.

Rice. 8. The photo shows different types of flagellated microbes.

Drank

Pili (villi, fimbriae) cover the surface of bacterial cells. The villus is a helically twisted thin hollow thread of protein nature.
General type drank provide adhesion (sticking) to host cells. Their number is huge and ranges from several hundred to several thousand. From the moment of attachment, any .
Sex drank facilitate the transfer of genetic material from the donor to the recipient. Their number is from 1 to 4 per cell.

Rice. 9. The photo shows E. coli. Flagella and pili are visible. The photo was taken using a tunneling microscope (STM).

Rice. 10. The photo shows numerous pili (fimbriae) of cocci.

Rice. 11. The photo shows a bacterial cell with fimbriae.

Cytoplasmic membrane

The cytoplasmic membrane is located under the cell wall and is a lipoprotein (up to 30% lipids and up to 70% proteins).
Different bacterial cells have different membrane lipid compositions.
Membrane proteins perform many functions. Functional proteins are enzymes due to which the synthesis of its various components, etc. occurs on the cytoplasmic membrane.
The cytoplasmic membrane consists of 3 layers. The phospholipid double layer is permeated with globulins, which ensure the transport of substances into the bacterial cell. If its function is disrupted, the cell dies.
The cytoplasmic membrane takes part in sporulation.

Rice. 12. The photo clearly shows a thin cell wall (CW), a cytoplasmic membrane (CPM) and a nucleotide in the center (the bacterium Neisseria catarrhalis).

Internal structure of bacteria

Rice. 13. The photo shows the structure of a bacterial cell. The structure of a bacterial cell differs from the structure of animal and plant cells - the cell lacks a nucleus, mitochondria and plastids.

Cytoplasm

The cytoplasm is 75% water, the remaining 25% is mineral compounds, proteins, RNA and DNA. The cytoplasm is always dense and motionless. It contains enzymes, some pigments, sugars, amino acids, a supply of nutrients, ribosomes, mesosomes, granules and all sorts of other inclusions. In the center of the cell, a substance is concentrated that carries hereditary information - the nucleoid.

Granules

The granules are made up of compounds that are a source of energy and carbon.

Mesosomes

Mesosomes are cell derivatives. They have different shapes - concentric membranes, vesicles, tubes, loops, etc. Mesosomes have a connection with the nucleoid. Participation in cell division and sporulation is their main purpose.

Nucleoid

A nucleoid is an analogue of a nucleus. It is located in the center of the cell. It contains DNA, the carrier of hereditary information in a folded form. Unwound DNA reaches a length of 1 mm. The nuclear substance of a bacterial cell does not have a membrane, a nucleolus or a set of chromosomes, and does not divide by mitosis. Before dividing, the nucleotide is doubled. During division, the number of nucleotides increases to 4.

Rice. 14. The photo shows a section of a bacterial cell. A nucleotide is visible in the central part.

Plasmids

Plasmids are autonomous molecules coiled into a ring of double-stranded DNA. Their mass is significantly less than the mass of a nucleotide. Despite the fact that hereditary information is encoded in the DNA of plasmids, they are not vital and necessary for the bacterial cell.

Rice. 15. The photo shows a bacterial plasmid. The photo was taken using an electron microscope.

Ribosomes

Ribosomes of a bacterial cell are involved in the synthesis of protein from amino acids. The ribosomes of bacterial cells are not united into the endoplasmic reticulum, like those of cells with a nucleus. It is ribosomes that often become the “target” for many antibacterial drugs.

Inclusions

Inclusions are metabolic products of nuclear and non-nuclear cells. They represent a supply of nutrients: glycogen, starch, sulfur, polyphosphate (valutin), etc. Inclusions often, when painted, take on a different appearance than the color of the dye. You can diagnose by currency.

Shapes of bacteria

The shape of a bacterial cell and its size are of great importance in their identification (recognition). The most common shapes are spherical, rod-shaped and convoluted.

Table 1. Main forms of bacteria.

Globular bacteria

The spherical bacteria are called cocci (from the Greek coccus - grain). They are arranged one by one, two by two (diplococci), in packets, in chains, and like bunches of grapes. This location depends on the method of cell division. The most harmful microbes are staphylococci and streptococci.

Rice. 16. In the photo there are micrococci. The bacteria are round, smooth, and white, yellow and red in color. In nature, micrococci are ubiquitous. They live in different cavities of the human body.

Rice. 17. The photo shows diplococcus bacteria - Streptococcus pneumoniae.

Rice. 18. The photo shows Sarcina bacteria. Coccoid bacteria cluster together in packets.

Rice. 19. The photo shows streptococcus bacteria (from the Greek “streptos” - chain).

Arranged in chains. They are causative agents of a number of diseases.

Rice. 20. In the photo, the bacteria are “golden” staphylococci. Arranged like “bunches of grapes”. The clusters are golden in color. They are causative agents of a number of diseases.

Rod-shaped bacteria

Rod-shaped bacteria that form spores are called bacilli. They have a cylindrical shape. The most prominent representative of this group is the bacillus. The bacilli include plague and hemophilus influenzae. The ends of rod-shaped bacteria may be pointed, rounded, chopped off, flared, or split. The shape of the sticks themselves can be regular or irregular. They can be arranged one at a time, two at a time, or form chains. Some bacilli are called coccobacilli because they have a round shape. But, nevertheless, their length exceeds their width.

Diplobacillus are double rods. Anthrax bacilli form long threads (chains).

The formation of spores changes the shape of the bacilli. In the center of the bacilli, spores form in butyric acid bacteria, giving them the appearance of a spindle. In tetanus bacilli - at the ends of the bacilli, giving them the appearance of drumsticks.

Rice. 21. The photo shows a rod-shaped bacterial cell. Multiple flagella are visible. The photo was taken using an electron microscope. Negative.

Rice. 22. The photo shows rod-shaped bacteria forming chains (anthrax bacilli).

What are bacteria

Bacteria means “stick” in Greek. This name does not mean that harmful bacteria are meant. They were given this name because of their shape. Most of these single cells look like rods. They also come in the form of triangles, squares, and star-shaped cells. For a billion years, bacteria do not change their appearance; they can only change internally. They can be movable or immobile. A bacterium consists of one cell. On the outside it is covered with a thin shell. This allows it to maintain its shape. There is no nucleus or chlorophyll inside the cell. There are ribosomes, vacuoles, cytoplasmic outgrowths, and protoplasm. The largest bacterium was found in 1999. It was called the "Grey Pearl of Namibia". Bacteria and bacillus mean the same thing, they just have different origins.

Man and bacteria

In our body there is a constant battle between harmful and beneficial bacteria. Thanks to this process, a person receives protection from various infections. Various microorganisms surround us at every step. They live on clothes, fly in the air, they are omnipresent.

The presence of bacteria in the mouth, and this is about forty thousand microorganisms, protects the gums from bleeding, from periodontal disease and even from sore throat. If a woman’s microflora is disturbed, she may develop gynecological diseases. Following basic rules of personal hygiene will help avoid such failures.

Human immunity completely depends on the state of the microflora. Almost 60% of all bacteria are found in the gastrointestinal tract alone. The rest are located in the respiratory system and in the reproductive system. About two kilograms of bacteria live in a person.

The appearance of bacteria in the body

A newly born baby has a sterile intestine.
After his first breath, many microorganisms enter the body with which he was previously unfamiliar. When the baby is first put to the breast, the mother transfers beneficial bacteria with milk, which will help normalize the intestinal microflora. It is not for nothing that doctors insist that the mother immediately after the birth of her child breastfeed him. They also recommend extending this feeding as long as possible.

Beneficial bacteria

Beneficial bacteria are: lactic acid bacteria, bifidobacteria, E. coli, streptomycents, mycorrhizae, cyanobacteria.

Types of harmful bacteria

Bacteria can be gram-positive, gram-negative, rod-shaped.

Names of harmful bacteria

Table. Harmful bacteria for humans. Titles

Titles	Habitat	Harm
Mycobacteria	food, water	tuberculosis, leprosy, ulcer
Tetanus bacillus	soil, skin, digestive tract	tetanus, muscle spasms, respiratory failure
Plague stick (considered by experts as a biological weapon)	only in humans, rodents and mammals	bubonic plague, pneumonia, skin infections
Helicobacter pylori	human gastric mucosa	gastritis, peptic ulcer, produces cytoxins, ammonia
Anthrax bacillus	the soil	anthrax
Botulism stick	food, contaminated dishes	poisoning

Harmful bacteria can stay in the body for a long time and absorb beneficial substances from it. However, they can cause an infectious disease.

The most dangerous bacteria

And another bacterium that can lead to human death is Mycobacterium tuberculosis. It causes tuberculosis, which is drug-resistant. If you do not seek help in a timely manner, a person may die.

Measures to prevent the spread of infections

The second stage is the destruction of pathways through which harmful bacteria can be transmitted. For this purpose, appropriate propaganda is carried out among the population.

Food facilities, reservoirs, and food storage warehouses are taken under control.

Bacteria are useful and harmful. Bacteria in human life

Bacteria are the most numerous inhabitants of planet Earth. They inhabited it in ancient times and continue to exist today. Some species have even changed little since then. Bacteria, beneficial and harmful, literally surround us everywhere (and even penetrate into other organisms). With a rather primitive unicellular structure, they are probably one of the most effective forms of living nature and are classified as a special kingdom.

Margin of safety

These microorganisms, as they say, do not drown in water and do not burn in fire. Literally: they can withstand temperatures up to plus 90 degrees, freezing, lack of oxygen, pressure – high and low. We can say that nature has invested a huge margin of safety in them.

Bacteria beneficial and harmful to the human body

As a rule, the bacteria that inhabit our bodies in abundance do not receive due attention. After all, they are so small that they seem to have no significant significance. Those who think so are largely mistaken. Beneficial and harmful bacteria have long and reliably “colonized” other organisms and successfully coexist with them. Yes, they cannot be seen without the help of optics, but they can benefit or harm our body.

Who lives in the intestines?

Doctors say that if you add together just the bacteria that live in the intestines and weigh them, you get something like three kilograms! Such a huge army cannot be ignored. Many microorganisms continuously enter the human intestine, but only some species find favorable conditions for living and living there. And in the process of evolution, they even formed a permanent microflora, which is designed to perform important physiological functions.

"Wise" neighbors

Bacteria have long played an important role in human life, although until very recently people had no idea about it. They help their owner with digestion and perform a number of other functions. What are these invisible neighbors?

Permanent microflora

99% of the population resides permanently in the intestines. They are ardent supporters and helpers of man.

Essential beneficial bacteria. Names: bifidobacteria and bacteroides. They are the vast majority.
Associated beneficial bacteria. Names: Escherichia coli, enterococci, lactobacilli. Their number should be 1-9% of the total.

You also need to know that under appropriate negative conditions, all these representatives of the intestinal flora (with the exception of bifidobacteria) can cause diseases.

What are they doing?

The main functions of these bacteria are to help us in the digestion process. It has been noted that dysbiosis can occur in a person with poor nutrition. The result is stagnation and poor health, constipation and other inconveniences. When a balanced diet is normalized, the disease usually recedes.

Another function of these bacteria is guard. They monitor which bacteria are beneficial. To ensure that “strangers” do not penetrate their community. If, for example, the causative agent of dysentery, Shigella Sonne, tries to penetrate the intestines, they kill it. However, it is worth noting that this only happens in the body of a relatively healthy person with good immunity. Otherwise, the risk of getting sick increases significantly.

Fickle microflora

Approximately 1% of the body of a healthy individual consists of so-called opportunistic microbes. They belong to the unstable microflora. Under normal conditions, they perform certain functions that do not harm humans and work for the benefit. But in certain situations they can manifest themselves as pests. These are mainly staphylococci and various types of fungi.

Dislocation in the gastrointestinal tract

In fact, the entire digestive tract has a heterogeneous and unstable microflora - beneficial and harmful bacteria. The esophagus contains the same inhabitants as in the oral cavity. In the stomach there are only a few that are acid-resistant: lactobacilli, Helicobacter, streptococci, fungi. The microflora in the small intestine is also sparse. Most bacteria are found in the colon. Thus, when defecating, a person is capable of excreting over 15 trillion microorganisms per day!

The role of bacteria in nature

It is also, of course, great. There are several global functions, without which all life on the planet would probably have ceased to exist long ago. The most important is sanitary. Bacteria eat dead organisms found in nature. They, in essence, work as a kind of wipers, preventing deposits of dead cells from accumulating. Scientifically they are called saprotrophs.

Another important role of bacteria is participation in the global cycle of substances on land and sea. On planet Earth, all substances in the biosphere pass from one organism to another. Without some bacteria, this transition would simply be impossible. The role of bacteria is invaluable, for example, in the circulation and reproduction of such an important element as nitrogen. There are certain bacteria in the soil that make nitrogenous fertilizers for plants from nitrogen in the air (microorganisms live right in their roots). This symbiosis between plants and bacteria is being studied by science.

Participation in food chains

As already mentioned, bacteria are the most numerous inhabitants of the biosphere. And accordingly, they can and should participate in food chains inherent in the nature of animals and plants. Of course, for humans, for example, bacteria are not a main part of the diet (unless they can be used as a food additive). However, there are organisms that feed on bacteria. These organisms, in turn, feed on other animals.

Cyanobacteria

These blue-green algae (an outdated name for these bacteria, fundamentally incorrect from a scientific point of view) are capable of producing huge amounts of oxygen through photosynthesis. Once upon a time, it was they who began to saturate our atmosphere with oxygen. Cyanobacteria continue to do this successfully to this day, producing a certain portion of the oxygen in the modern atmosphere!

What types of bacteria are there: names and types

Let's talk about their structure, functions, and also name some useful and harmful types.

Discovery of bacteria

Let's begin our excursion into the kingdom of microorganisms with a definition. What does "bacteria" mean?

The term comes from the ancient Greek word for "stick". Christian Ehrenberg introduced it into the academic lexicon. These are anucleate microorganisms, consisting of one cell and without a nucleus. Previously, they were also called “prokaryotes” (nuclear-free). But in 1970 there was a division into archaea and eubacteria. However, this concept is still more often used to mean all prokaryotes.

The science of bacteriology studies what types of bacteria there are. Scientists say that at this time about ten thousand different types of these living creatures have been discovered. However, it is believed that there are more than a million varieties.

Anton Leeuwenhoek, a Dutch naturalist, microbiologist and fellow of the Royal Society of London, in a letter to Great Britain in 1676, describes a number of simple microorganisms that he discovered. His message shocked the public, and a commission was sent from London to double-check this data.

After Nehemiah Grew confirmed the information, Leeuwenhoek became a world-famous scientist, the discoverer of the simplest organisms. But in his notes he called them “animalcules.”

Ehrenberg continued his work. It was this researcher who coined the modern term “bacteria” in 1828.

Robert Koch became a revolutionary in microbiology. In his postulates, he associates microorganisms with various diseases, and identifies some of them as pathogens. In particular, Koch discovered the bacterium that causes tuberculosis.

If before this the simplest were studied only in general terms, then after 1930, when the first electron microscope was created, science made a leap in this direction. For the first time, an in-depth study of the structure of microorganisms begins. In 1977, the American scientist Carl Woese divided prokaryotes into archaea and bacteria.

Thus, it is safe to say that this discipline is only at the very beginning of its development. Who knows how many more discoveries await us in the coming years.

Structure

3rd graders already know firsthand what types of bacteria there are. Children study the structure of microorganisms in class. Let's delve a little deeper into this topic to restore the information. Without it, it will be difficult for us to discuss subsequent points.

The bulk of bacteria consists of just one cell. But it comes in different forms.

The structure depends on the way of life and food supply of the microorganism. Thus, cocci (round), clostridia and bacilli (rod-shaped), spirochetes and vibrios (twisting), in the form of cubes, stars and tetrahedrons are found. It has been observed that with a minimum amount of nutrients in the environment, bacteria tend to increase their surface area. They grow additional formations. Scientists call these outgrowths “prostek.”

So, after we have found out what forms of bacteria there are, it is worth touching on their internal structure. Single-celled microorganisms have a constant set of three structures. Additional elements may vary, but the basics will always be the same.

So, every bacterium necessarily has an energy structure (nucleotide), non-membrane organelles responsible for the synthesis of protein from amino acids (ribosomes) and a protoplast. The latter includes the cytoplasm and the cytoplasmic membrane.

The cell membrane is protected from aggressive external influences by a membrane, which consists of a wall, a capsule and a sheath. Some species also have surface structures such as villi and flagella. They are designed to help bacteria move efficiently through space to obtain food.

Metabolism

It is especially worth focusing on heterotrophic bacteria. Different species require specific amounts of substances. For example, Bacillus fastidiosus is found only in urine, since it can only obtain carbon from this acid. We will talk about such microorganisms in more detail below.

Now it’s worth focusing on methods of replenishing energy in the cell. Modern science knows only three of these. Bacteria use photosynthesis, respiration or fermentation.

Photosynthesis, in particular, can occur either with the use of oxygen or without the participation of this element. Purple, green and heliobacteria survive without it. They produce bacteriochlorophyll. Oxygen photosynthesis requires ordinary chlorophyll. These include prochlorophytes and cyanobacteria.

A discovery was recently made. Scientists have discovered microorganisms that use hydrogen obtained from the breakdown of water for reactions in cells. But that is not all. For this reaction, it is necessary to have uranium ore nearby, otherwise the desired result will not be obtained.

Also, in the deep-sea layers of the world's oceans and on its bottom, there are colonies of bacteria that transmit energy only with the help of electric current.

Reproduction

Earlier we talked about what types of bacteria there are. We will now consider the types of reproduction of these microorganisms.

There are three methods by which these creatures increase their numbers.

This is sexual reproduction in a primitive form, budding and equal transverse division.

In sexual reproduction, offspring are produced through transduction, conjugation and transformation.

Place in the world

Previously, we figured out what bacteria are. Now it’s worth talking about what role they play in nature.

The total biomass of prokaryotes is about five hundred billion tons. It stores more than eighty percent of phosphorus, nitrogen and carbon.

Bacteria and humans

We have already figured out what bacteria are, what they look like, and what they can do. Now it’s worth talking about what their role is in the life of a modern person.

Firstly, we have been using the amazing abilities of lactic acid bacteria for many centuries. Without these microorganisms, there would be no kefir, yogurt, or cheese in our diet. In addition, such creatures are also responsible for the fermentation process.

In agriculture, bacteria are used in two ways. On the one hand, they help get rid of unnecessary weeds (phytopathogenic organisms, like herbicides), on the other hand, from insects (entomopathogenic unicellular organisms, like insecticides). In addition, humanity has learned to create bacterial fertilizers.

Microorganisms are also used for military purposes. With the help of various types, deadly biological weapons are created. To do this, not only the bacteria themselves are used, but also the toxins released by them.

Peacefully, science uses single-celled organisms for research in genetics, biochemistry, genetic engineering and molecular biology. With the help of successful experiments, algorithms for the synthesis of vitamins, proteins and other substances necessary for humans were created.

Bacteria are used in other areas as well. With the help of microorganisms, ores are enriched and water bodies and soils are cleaned.

Scientists also say that the bacteria that make up the microflora in the human intestine can be called a separate organ with its own tasks and independent functions. According to researchers, there is about one kilogram of these microorganisms inside the body!

In everyday life, we encounter pathogenic bacteria everywhere. According to statistics, the largest number of colonies are found on the handles of supermarket trolleys, followed by computer mice in Internet cafes, and only in third place are the handles of public restrooms.

Beneficial bacteria

Today, in conditions of poor nutrition, stress, and an overabundance of antibiotics, dysbiosis and related problems are taking leading positions. How do doctors propose to deal with this?

One of the main answers is the use of probiotics. This is a special complex that repopulates the human intestines with beneficial bacteria.

Such an intervention can help with such unpleasant issues as food allergies, lactose intolerance, gastrointestinal disorders and other ailments.

Let's now touch on what beneficial bacteria there are, and also learn about their effect on health.

Three types of microorganisms have been studied in the most detail and are widely used to have a positive effect on the human body: acidophilus, Bulgarian bacillus and bifidobacteria.

Harmful bacteria

There are some that are harmful only to humans, while others are deadly for animals or plants. People have learned to use the latter, in particular, to destroy weeds and annoying insects.

The worst thing is that just one cell, once in the favorable environment of the human body, is capable of multiplying to several million bacteria within just a few hours.

Preventive measures to prevent the disease are of three types. These are vaccinations and vaccinations, interruption of transmission routes (gauze bandages, gloves) and quarantine.

Where do bacteria in urine come from?

Some people try to monitor their health and get tested at the clinic. Very often the cause of poor results is the presence of microorganisms in the samples.

We'll talk about what bacteria are in urine a little later. Now it is worthwhile to dwell separately on where, in fact, single-celled creatures appear there.

Ideally, a person's urine is sterile. There cannot be any foreign organisms there. The only way bacteria can enter the waste is at the site where waste is removed from the body. In particular, in this case it will be the urethra.

If the analysis shows a small number of inclusions of microorganisms in the urine, then everything is normal for now. But when the indicator increases above the permitted limits, such data indicate the development of inflammatory processes in the genitourinary system. This may include pyelonephritis, prostatitis, urethritis and other unpleasant ailments.

Thus, the question of what types of bacteria are in the bladder is completely incorrect. Microorganisms do not enter the discharge from this organ. Scientists today have identified several reasons leading to the presence of single-celled creatures in urine.

Firstly, this is promiscuous sex life.
Secondly, diseases of the genitourinary system.
Thirdly, neglect of personal hygiene rules.
Fourthly, decreased immunity, diabetes and a number of other disorders.

Types of bacteria in urine

Earlier in the article it was said that microorganisms in waste are found only in cases of disease. We promised to tell you what bacteria are. The names will be given only of those species that are most often found in the analysis results.

So, let's begin. Lactobacillus is a representative of anaerobic organisms, a gram-positive bacterium. It must be in the human digestive system. Its presence in the urine indicates some malfunctions. Such an event is not critical, but it is an unpleasant wake-up call that you should take serious care of yourself.

Proteus is also a natural inhabitant of the gastrointestinal tract. But its presence in the urine indicates a failure in the excretion of feces. This microorganism passes from food into urine only in this way. A sign of the presence of a large amount of proteus in the waste is a burning sensation in the lower abdomen and painful urination when the liquid is dark in color.

Enterococcus fecalis is very similar to the previous bacterium. It gets into the urine the same way, multiplies quickly and is difficult to treat. In addition, enterococcus microorganisms are resistant to most antibiotics.

Thus, in this article we have figured out what bacteria are. We talked about their structure and reproduction. You have learned the names of some harmful and beneficial species.

Good luck, dear readers! Remember that following the rules of personal hygiene is the best prevention.

Most people view various bacterial organisms solely as harmful particles that can provoke the development of various pathological conditions. Nevertheless, according to scientists, the world of these organisms is very diverse. There are frankly dangerous bacteria that pose a danger to our body, but there are also useful ones - those that ensure the normal functioning of our organs and systems. Let's try to understand these concepts a little and consider individual types of such organisms. Let's talk about bacteria in nature that are harmful and beneficial to humans.

Beneficial bacteria

Scientists say that bacteria became the very first inhabitants of our big planet, and it is thanks to them that there is life on Earth now. Over the course of many millions of years, these organisms gradually adapted to the constantly changing conditions of existence, they changed their appearance and habitat. Bacteria were able to adapt to the environment and were able to develop new and unique methods of life support, including multiple biochemical reactions - catalysis, photosynthesis and even seemingly simple respiration. Now bacteria coexist with human organisms, and such cooperation is characterized by some harmony, because such organisms are capable of bringing real benefits.

After a little person is born, bacteria immediately begin to penetrate into his body. They penetrate the respiratory tract along with the air, enter the body along with breast milk, etc. The entire body becomes saturated with various bacteria.

It is impossible to accurately calculate their number, but some scientists boldly say that the number of such cells in the body is comparable to the number of all cells. The digestive tract alone is home to four hundred different types of living bacteria. It is believed that a certain variety can grow only in a specific place. Thus, lactic acid bacteria are able to grow and multiply in the intestines, others feel optimal in the oral cavity, and some live only on the skin.

Over many years of coexistence, humans and such particles were able to recreate optimal conditions for cooperation for both groups, which can be characterized as a useful symbiosis. At the same time, bacteria and our body combine their capabilities, while each side remains in the black.

Bacteria are capable of collecting particles of various cells on their surface, which is why the immune system does not perceive them as hostile and does not attack them. However, after organs and systems are exposed to harmful viruses, beneficial bacteria rise to the defense and simply block the path of pathogens. When existing in the digestive tract, such substances also bring tangible benefits. They process leftover food, releasing a significant amount of heat. It, in turn, is transmitted to nearby organs, and is transferred throughout the body.

A deficiency of beneficial bacteria in the body or a change in their number causes the development of various pathological conditions. This situation can develop while taking antibiotics, which effectively destroy both harmful and beneficial bacteria. To correct the number of beneficial bacteria, special preparations - probiotics - can be consumed.

Harmful bacteria

However, it is worth remembering that not all bacteria are human friends. Among them there are also many dangerous varieties that can only cause harm. Such organisms, after entering our body, become the cause of the development of various bacterial ailments. These include various colds, some types of pneumonia, and also syphilis, tetanus and other diseases, even deadly ones. There are also diseases of this type that are transmitted by airborne droplets. This is dangerous tuberculosis, whooping cough, etc.

A significant number of ailments caused by harmful bacteria develop due to the consumption of insufficiently high-quality food, unwashed and unprocessed vegetables and fruits, raw water, and undercooked meat. You can protect yourself from such diseases by following the rules and regulations of hygiene. Examples of such dangerous illnesses are dysentery, typhoid fever, etc.

Manifestations of diseases that develop as a result of an attack by bacteria are the result of the pathological influence of poisons that these organisms produce or that are formed against the background of their destruction. The human body is able to get rid of them thanks to its natural defense, which is based on the process of phagocytosis of bacteria by white blood cells, as well as on the immune system, which synthesizes antibodies. The latter bind foreign proteins and carbohydrates, and then simply eliminate them from the bloodstream.

Also, harmful bacteria can be destroyed using natural and synthetic medications, the most famous of which is penicillin. All drugs of this type are antibiotics; they differ depending on the active component and the mode of action. Some of them are capable of destroying the cell membranes of bacteria, while others suspend their vital processes.

So, in nature there are a lot of bacteria that can bring benefits and harm to humans. Fortunately, the modern level of development of medicine makes it possible to cope with most pathological organisms of this kind.

Help me, I need a brief description of beneficial and harmful bacteria, all of them are not covered, they are not missing, please help me

Eternity............

The danger of bacterial diseases was greatly reduced at the end of the 19th century with the invention of vaccination, and in the middle of the 20th century with the discovery of antibiotics.

Useful; For thousands of years, people have used lactic acid bacteria to produce cheese, yogurt, kefir, vinegar, and fermentation.

Currently, methods have been developed for the use of phytopathogenic bacteria as safe herbicides, and entomopathogenic bacteria instead of insecticides. The most widely used is Bacillus thuringiensis, which produces toxins (Cry-toxins) that affect insects. In addition to bacterial insecticides, bacterial fertilizers are used in agriculture.

Bacteria that cause human disease are used as biological weapons.

Due to their rapid growth and reproduction, as well as their simple structure, bacteria are actively used in scientific research in molecular biology, genetics, genetic engineering and biochemistry. The most well-studied bacterium is Escherichia coli. Information about bacterial metabolic processes has made it possible to produce bacterial synthesis of vitamins, hormones, enzymes, antibiotics, etc.

A promising direction is the enrichment of ores using sulfur-oxidizing bacteria, the purification of soils and water bodies contaminated with petroleum products or xenobiotics by bacteria.

The human intestine normally contains from 300 to 1000 species of bacteria with a total mass of up to 1 kg, and the number of their cells is an order of magnitude greater than the number of cells in the human body. They play an important role in the digestion of carbohydrates, synthesize vitamins, and displace pathogenic bacteria. We can figuratively say that the human microflora is an additional “organ” that is responsible for protecting the body from infections and digestion.

It's not entirely short. but I think you can shorten it as you like.

Karim Murotaliev

Yulia Stoika

1. Azotobacter - enrich the soil with biologically active substances that stimulate plant growth, help cleanse the soil of heavy metals, in particular lead and mercury.
2.Bifidobacteria:
supply the body with vitamin K, thiamine (B1), riboflavin (B2), nicotinic acid (B3), pyridoxine (B6), folic acid (B9), amino acids and proteins;
prevent the development of pathogenic microbes;
protect the body from toxins from the intestines;
accelerate the digestion of carbohydrates;
activate parietal digestion;
help the absorption of calcium, iron, and vitamin D ions through the intestinal walls.
3.Lactic acid bacteria - protect the intestines from putrefactive and pathogenic microbes.
4.Streptomycetes:
are manufacturers (producers) of a wide variety of drugs, including:
antifungal;
antibacterial;

What are bacteria

Bacteria means “stick” in Greek. This name does not mean that harmful bacteria are meant.

They were given this name because of their shape. Most of these single cells look like rods. They also come in squares and star-shaped cells. For a billion years, bacteria do not change their appearance; they can only change internally. They can be movable or immobile. Bacteria On the outside it is covered with a thin shell. This allows it to maintain its shape. There is no nucleus or chlorophyll inside the cell. There are ribosomes, vacuoles, cytoplasmic outgrowths, and protoplasm. The largest bacterium was found in 1999. It was called the "Grey Pearl of Namibia". Bacteria and bacillus mean the same thing, they just have different origins.

Man and bacteria

The appearance of bacteria in the body

A newly born baby has a sterile intestine.

After his first breath, many microorganisms enter the body with which he was previously unfamiliar. When the baby is first put to the breast, the mother transfers beneficial bacteria with milk, which will help normalize the intestinal microflora. It is not for nothing that doctors insist that the mother immediately after the birth of her child breastfeed him. They also recommend extending this feeding as long as possible.

Beneficial bacteria

Beneficial bacteria are: lactic acid bacteria, bifidobacteria, E. coli, streptomycents, mycorrhizae, cyanobacteria.

Types of harmful bacteria

Harmful bacteria can cause a number of serious illnesses in humans. For example, diphtheria, sore throat, plague and many others. They are easily transmitted from an infected person through air, food, or touch. It is the harmful bacteria, the names of which will be given below, that spoil food. They give off an unpleasant odor, rot and decompose, and cause diseases.

Bacteria can be gram-positive, gram-negative, rod-shaped.

Names of harmful bacteria

Table. Harmful bacteria for humans. Titles

Titles	Habitat	Harm
Mycobacteria	food, water	tuberculosis, leprosy, ulcer
Tetanus bacillus	soil, skin, digestive tract	tetanus, muscle spasms, respiratory failure
Plague stick (considered by experts as a biological weapon)	only in humans, rodents and mammals	bubonic plague, pneumonia, skin infections
Helicobacter pylori	human gastric mucosa	gastritis, peptic ulcer, produces cytoxins, ammonia
Anthrax bacillus	the soil	anthrax
Botulism stick	food, contaminated dishes	poisoning

Harmful bacteria can stay in the body for a long time and absorb beneficial substances from it. However, they can cause an infectious disease.

The most dangerous bacteria

One of the most resistant bacteria is methicillin. It is better known as Staphylococcus aureus (Staphylococcus aureus). can cause not one, but several infectious diseases. Some types of these bacteria are resistant to powerful antibiotics and antiseptics. Strains of this bacterium can live in the upper respiratory tract, open wounds and urinary tract of every third inhabitant of the Earth. For a person with a strong immune system, this does not pose a danger.

And another bacterium that can lead to the death of a person is It causes tuberculosis, which is resistant to drugs. If you do not seek help in a timely manner, a person may die.

Measures to prevent the spread of infections

The second stage is the destruction of pathways through which harmful bacteria can be transmitted. For this purpose, appropriate propaganda is carried out among the population.

Food facilities, reservoirs, and food storage warehouses are taken under control.