Everyone knows that bacteria are the most ancient type of living creatures that inhabit our planet. The first bacteria were the most primitive, but as our earth changed, so did the bacteria. They are present everywhere, in water, on land, in the air we breathe, in food, in plants. Just like people, bacteria can be good and bad.

Beneficial bacteria are:

• Lactic acid or lactobacilli. One of these good bacteria is lactic acid bacteria. This is a rod-shaped type of bacteria that lives in dairy and fermented milk products. These bacteria also inhabit the human oral cavity, intestines, and vagina. The main benefit of these bacteria is that they produce lactic acid as a fermentation, thanks to which we get yogurt, kefir, fermented baked milk from milk, in addition, these products are very useful for humans. In the intestines, they play the role of cleansing the intestinal environment from bad bacteria.
• Bifidobacteria. Bifidobacteria are found mainly in the gastrointestinal tract, just like lactic acid bacteria are capable of producing lactic acid and acetic acid, due to which these bacteria control the growth of pathogenic bacteria, thereby regulating the pH level in our intestines. Various varieties of bifidobacteria help get rid of constipation, diarrhea, and fungal infections.
• Escherichia coli. The human intestinal microflora consists of most microbes of the Escherichia coli group. They promote good digestion and are also involved in certain cellular processes. But some varieties of this stick can cause poisoning, diarrhea, and kidney failure.
• Streptomycetes. The habitat of streptomycetes is water, decomposing compounds, soil. Therefore, they are especially useful for the environment, because... Many processes of decomposition and combinations are carried out with them. In addition, some of these bacteria are used in the production of antibiotics and antifungal drugs.

Harmful bacteria are:

• Streptococci. Chain-shaped bacteria, which, when entering the body, are the causative agents of many diseases, such as tonsillitis, bronchitis, otitis media and others.
• Plague stick. A rod-shaped bacterium that lives in small rodents causes terrible diseases such as plague or pneumonia. Plague is a terrible disease that can destroy entire countries, and it has been compared to biological weapons.
• Helicobacter pylori. The habitat of Helicobacter pylori is the human stomach, but in some people the presence of these bacteria causes gastritis and ulcers.
• Staphylococcus. The name staphylococcus comes from the fact that the shape of the cells resembles a bunch of grapes. For humans, these bacteria cause severe diseases with intoxication and purulent formations. No matter how terrible bacteria are, humanity has learned to survive among them thanks to vaccination.

Which do not have a core. Most bacteria are heterotrophs, but there are also autotrophs. They reproduce by division. When unfavorable conditions occur, some bacteria form spores.

Bacteria can only be seen through a microscope, which is why they are called microorganisms. Microorganisms are studied by the science of microbiology. The branch of microbiology that studies bacteria is called bacteriology.

The first to see and describe bacteria was the Dutch naturalist Anthony van Leeuwen Hoek (1632-1723). He learned to grind glass and make lenses. Leeuwenhoek made more than 400 microscopes and discovered the world of microscopic organisms - bacteria and protists.

When we hear about bacteria, we most often imagine a sore throat or gums, despite the fact that only a small part of bacteria cause disease. Most of these organisms perform other important functions.

We begin to come into contact with bacteria from the first hours of life. Many of them constantly live on the surface of human skin. There are even more of them on the teeth, gums, tongue and walls of the mouth. There are more bacteria in your mouth than there are people on Earth! But the largest number of them lives in the intestines - up to 5 kg in an adult.

Bacteria are found everywhere: in water, soil, air, in plant tissues, in the bodies of animals and humans. They live where they find enough food, moisture and favorable temperatures (10-40 ° C). Most of them require oxygen. There are also bacteria that live in hot springs (with a temperature of 60-90 ° C), extremely salty bodies of water, in volcanic vents, deep in the oceans where sunlight does not penetrate. Even in the coldest regions (Antarctica) and on the highest mountain peaks, bacteria live.

Different numbers of bacteria are found in different places. There are fewer of them in the air, especially in natural conditions. And in crowded places, such as cinemas, train stations, and classrooms, there are much more of them. Therefore, it is necessary to ventilate the premises frequently.

In river waters, especially near large cities, there can be a lot of bacteria - up to several hundred thousand per 1 mm3. Therefore, you should not drink raw water from open reservoirs. There are a lot of bacteria in the water of the seas and oceans.

There are even more bacteria in the soil - up to 100 million per 1 g of humus (fertile soil layer).

Bacteria are very small organisms. The largest bacteria can be seen under a light microscope.

To get acquainted with the smallest ones, an electron microscope is required (Fig. 7).

Most of the bacteria that inhabit our home and our body are in the form of balls, rods and spirals. Spherical bacteria are called cocci, rod-shaped bacteria are called bacilli, and spiral-shaped bacteria are called spirilla (Fig. 9). Some bacteria form chains, located close to each other.

Consider the structure of a bacterial cell in Figure 10. It includes cytoplasm, surrounded by a cytoplasmic membrane and a cell membrane (cell wall). The shell gives the bacterium a certain shape and serves as protection from unfavorable conditions.

Additional protection for many bacteria will be provided by the mucus layer located on the outside of the shell. The surface of the bacterial cell is covered with numerous villi, which are hollow outgrowths of the cytoplasmic membrane. Some bacteria have one or more filamentous flagella.

The main difference between bacteria is the absence of a nucleus, i.e. they are prokaryotes.

It is on this basis that they are separated into a separate kingdom. The nuclear material of bacteria is the bacterial chromosome: it carries hereditary information.

Most bacteria are heterotrophs. They consume ready-made organic substances. Their food consists of living and dead organisms, human food products, wastewater, etc.

Saprotrophs

Some heterotrophic bacteria use organic substances from dead bodies or secretions of living organisms. These are saprotrophs (from the Greek sapros - rotten and trophos - nutrition).

There are also autotrophic bacteria. They are capable of forming organic substances from inorganic ones (carbon dioxide, water, hydrogen sulfide, etc.). Autotrophic photosynthetic bacteria have bacterial chlorophyll in their cells, with which they form organic substances under the influence of solar energy.

Cyanobacteria

An example of autotrophic bacteria is cyanobacteria. They make their own food from carbon dioxide and water when exposed to sunlight. At the same time, they release oxygen, enriching their habitat.

Bacteria reproduce by division. In this case, from one mother cell two daughter cells are formed, similar to the mother one. Under favorable conditions (sufficient nutrition, humidity and temperature from 10 to 30 ° C), bacteria can divide every 20-30 minutes, so their number increases very quickly. Material from the site

If bacteria are cultivated (grown) on a nutrient medium under favorable conditions, they multiply very quickly and form colonies of up to 4 billion cells. Colonies of bacteria of certain species have characteristic outlines and colors (Fig. 8). By the type of colonies, you can determine the presence of certain bacteria in a particular material.

Some bacteria move using flagella. The base of the flagellum rotates, and it seems to be screwed into the medium, ensuring the movement of the bacterium. Most bacteria move passively: some with the help of air currents, others with the flow of water. This is how they are distributed.

Under unfavorable conditions (lack of food, moisture, sudden temperature fluctuations), bacteria can turn into spores. The cytoplasm near the bacterial chromosome becomes denser. A very strong shell is formed around it. Spores formed in this way can exist for hundreds of years (Fig. 11).

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, one species includes strains of bacteria 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%. 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.

Bacteria are the smallest ancient microorganisms invisible to the naked eye. Only under a microscope can one examine their structure, appearance and interaction with each other. The first microorganisms had a primitive structure; they developed, mutated, created colonies, and adapted to a changing environment. Bacteria of different species exchange amino acids with each other, which are necessary for growth and development.

Types of bacteria

School biology textbooks contain images of different types of bacteria, differing in shape:

1. Cocci are spherical organisms that differ in their relative positions. Under a microscope, it is noticeable that streptococci form a chain of balls, diplococci live in pairs, and staphylococci live in randomly shaped clusters. A number of cocci cause various inflammatory processes when they enter the human body (gonococcus, staphylococcus, streptococcus). Not all cocci living in the human body are pathogenic. Conditionally pathogenic species take part in the formation of the body’s defenses against external influences and are safe if the balance of the flora is maintained.
2. Rod-shaped ones differ in shape, size and ability to form spores. Spore-forming species are called bacilli. The bacilli include: tetanus bacillus, anthrax bacillus. Spores are formations inside a microorganism. The spores are insensitive to chemical treatment, their resistance to external influences is the key to preserving the species. It is known that spores are destroyed at high temperatures (above 120ºC).

Shapes of rod-shaped microbes:

• with pointed poles, like fusobacterium, which is part of the normal microflora of the upper respiratory tract;
• with thickened poles resembling a club, like corynebacterium - the causative agent of diphtheria;
• with rounded ends, such as those of E. coli, which are necessary for the digestion process;
• with straight ends, like the anthrax bacillus.

Most rod-shaped bacilli and bacteria are located chaotically in relation to each other. We can distinguish streptobacteria (streptobacilli), which are arranged in a chain, and diplobacteria (diplobacillus), which exist in pairs.

3. Spirilla and spirochetes are convoluted microorganisms. They do not form spores and are very mobile. Under a microscope you can see their rapid movements. Most spirilla are safe for humans and animals. They are saprophytes and feed on non-living substrates. The exception is species that cause sodoku. Spirochetes are more dangerous for humans and animals; they can cause diseases of the skin, respiratory tract, and gastrointestinal tract. Spirillae differ from spirochetes in having fewer whorls and the presence of flagella at the poles.

4. Vibrios are vibrating microbes. When viewed under a microscope, you can see their vibrating movements. The microorganism changes depending on environmental conditions. Vibrios come in spiral, rod-shaped, thread-like, and spherical shapes. The most dangerous for humans is vibrio cholera.

Gram(+) and gram(-)

Danish microbiologist Hans Gram conducted an experiment more than 100 years ago, after which all bacteria began to be classified as gram-positive and gram-negative. Gram-positive organisms create a long-term stable bond with the coloring substance, which is enhanced by exposure to iodine. Gram-negative, on the contrary, are not susceptible to the dye, their shell is firmly protected.

Gram-negative microbes include chlamydia, rickettsia, and gram-positive microbes include staphylococci, streptococci, and corynebacteria.

Today in medicine the test for gram(+) and gram(-) bacteria is widely used. Gram staining is one of the methods for studying mucous membranes to determine the composition of the microflora.

Aerobic and anaerobic

The most primitive bacteria live deep underwater. They do not need access to oxygen to develop. More developed colonies have reached land and live on surfaces. To reproduce and develop a colony, these microorganisms need oxygen. Given their dependence on oxygen, groups of microorganisms are called aerobic and anaerobic.

Aerobic microorganisms require oxygen for development and respiration:

Obligate aerobes - these bacteria live freely in the external environment. An example is the tuberculosis bacillus, which is resistant to the environment, persists in water for up to 5 months, and in a humid, warm and dark room for up to 7 years.

Microaerophiles - these microbes need 2% oxygen for normal life and development. They are streptococci, which cause pharyngitis, scarlet fever and live in the respiratory tract. When microbes are grown in a liquid environment, these organisms accumulate close to the surface, where the oxygen content is low.

Anaerobic microorganisms are able to grow and reproduce without oxygen:

• obligate anaerobes avoid molecular oxygen (for example, fusobacteria);
• facultative ones are capable of growth and development in the presence of oxygen and without it, these can be streptococci, gonococci;
• aerotolerant microorganisms do not use oxygen for development, although they grow in the presence of molecular oxygen, like lactic acid fermentation bacteria.

How do bacteria live

Biologists define bacteria as a separate kingdom; they are different from other living things. It is a single-celled organism without a nucleus inside. Their shape can be in the form of a ball, cone, stick, or spiral. Prokaryotes use flagella to move.

Biofilm is a city for microorganisms and goes through several stages of formation:

• Adhesion or sorption is the attachment of a microorganism to a surface. As a rule, films are formed at the interface of two media: liquid and air, liquid and liquid. The initial stage is reversible and film formation can be prevented.
• Fixation - bacteria release polymers, ensuring their strong fixation, forming a matrix for strength and protection.
• Maturation - microbes merge, exchange nutrients, and microcolonies develop.
• Growth stage - bacteria accumulate, merge, and are displaced. The number of microorganisms ranges from 5 to 35%, the rest of the space is occupied by the intercellular matrix.
• Dispersion - microorganisms periodically detach from the film, attach to other surfaces and form a biofilm.

The processes that occur in a biofilm are different from what happens to a microbe that is not part of the colony. Colonies are stable, microbes organize a unified system of behavioral reactions, determining the interaction of members inside the matrix and outside the film. Human mucous membranes are inhabited by a large number of microorganisms that produce a gel for protection and ensure the stability of the functioning of organs. An example is the gastric mucosa. It is known that Helicobacter pylori, which is considered the cause of gastric ulcers, is present in more than 80% of examined people, but not everyone develops peptic ulcers. It is assumed that Helicobacter pylori, being members of the colony, is involved in digestion. Their ability to cause harm manifests itself only after certain conditions are created.

The interaction of bacteria in biofilms is still poorly understood. But today, some microbes have become human assistants when carrying out restoration work and increasing the strength of coatings. In Europe, manufacturers of disinfectants offer to treat surfaces with bacterial solutions containing safe microorganisms that prevent the development of pathogenic flora. Bacteria are used to create polymer compounds and will also eventually generate electricity.

In one experiment, mutations in E. coli were observed. The bacteria were divided into different groups: “winners” and “outsiders.” The “winners” initially had beneficial mutations in their genes. For more than 20 years, a group of scientists changed the environment daily, keeping the microbes in a state of glucose deficiency. Contrary to expectations, “outsider” microorganisms, which did not have a competitive advantage at first, acquired additional mutations much earlier in the course of evolution and showed better adaptation results than colonies with more developed genes at the start. Bacteria have proven that good starting data does not affect the final result.