Beneficial and harmful bacteria. The structure of bacteria

The totality of bacteria that live in the human body is called the microbiota. A healthy gut microflora is made up of many bacteria. There are over a million of them. Each microorganism plays a huge role in the normalization of the functioning of the whole organism. If the balance is disturbed and there is a shortage of any bacteria, this leads to disturbances in the digestive tract. The disease process begins to develop rapidly. All beneficial microorganisms are found mostly in the intestines, as well as on the surface of the skin and mucous membranes. The immune system is able to regulate the necessary amount of beneficial bacteria.

The microflora of the human body is inhabited by both beneficial and pathogenic organisms. In a certain concentration, this is considered the norm. There are beneficial and pathogenic bacteria. Of course, there are many more beneficial microorganisms in the intestines. The balance is maintained only when the good microflora is more than 95 percent of all microorganisms. There are such types of bacteria that live in the human body:

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

bifidobacteria

They are the most common type of bacteria. They are directly involved in the formation of lactic acid and acetate. Bifidobacteria contribute to the creation of an acidic environment, which helps to neutralize almost all pathogenic bacteria. In this case, the pathogenic flora can no longer develop further. The processes of decay and fermentation stop in the body.

Bifidobacteria are very important for the child's body. They are responsible for allergic reactions to various foods. They also have a good antioxidant effect, prevent the development of tumors.

This type of bacteria is involved in the synthesis of vitamin C. They help the rapid absorption of vitamins B and D, which are involved in the formation of the child's body. If there are few bifidobacteria in the body, then even synthetic vitamins will not be able to fully replenish their required amount.

lactobacilli

These microorganisms also play a rather important role in the normal functioning of the body. They are able to interact with other good bacteria that inhabit the intestines. At the same time, they block the development of pathogenic microflora and suppress the vital activity of bacteria that cause intestinal diseases.

Lactobacilli take part in the formation of lysozyme, lactic acid and some vitamins. They are great helpers for the immune system. Deficiency of these bacteria almost always leads to the development of dysbacteriosis.

Often lactobacilli can be found not only in the intestines, but also on the mucous membranes. This is a very important factor, especially for women's health. With their help, the necessary acidity in the vagina is maintained. This helps prevent the development of diseases such as bacterial vaginosis.

Enterococci

Appear in the human body in the first days after birth. Promote good absorption of sucrose. Most often, enterococci are found in the small intestine. Interacting with other good bacteria, they protect the body from the development of pathogenic microflora. However, this type of microorganisms is considered to be conditionally safe. If their concentration is exceeded, intestinal diseases develop.

coli

Many types of such microorganisms do not contribute to the development of any diseases. In some cases, they also perform a protective function. Their usefulness lies in the synthesis of cocilin, which creates an obstacle to the reproduction of pathogenic microflora. E. coli takes part in the synthesis of many vitamins, as well as nicotinic and folic acid. This is very important because folic acid is responsible for the formation of red blood cells in the body, which helps maintain hemoglobin levels.

Positive effect of bacteria on the human body

Good bacteria have a lot of useful and necessary properties. The body is able to function normally as long as it maintains the right balance between the bacteria that inhabit the intestines and mucous membranes. A lot of them are involved in the most important process of vitamin synthesis. B vitamins cannot be absorbed normally without exposure to beneficial bacteria. Because of this, the level of hemoglobin in the blood can decrease, skin integuments suffer, and disorders of the nervous system are observed.

Bacteria are able to break down undigested food components that reach the large intestine. Beneficial microorganisms help maintain the water-salt balance in the body.

The intestinal microflora is involved in the formation of local immunity. Helps to block the reproduction of pathogenic microorganisms. Therefore, people do not feel bloating and the development of flatulence. An increase in the number of lymphocytes provokes the work of phagocytes, which is to fight harmful microbes. At the same time, some bacteria are actively involved in the synthesis of immunoglobulin A.

Beneficial microorganisms have a positive effect on the functioning of the large and small intestines. With their help, it is possible to maintain the necessary acidity, as a result of which the epithelium becomes more resistant to the effects of harmful factors. The peristalsis of the intestine also depends on microorganisms. Bifidobacteria are involved in blocking the processes of decay and fermentation in the body. Many bacteria are constantly in symbiosis with pathogens, controlling their effect on the body.

The overall balance of the body is maintained by biochemical reactions occurring in the body with the participation of bacteria. In this case, thermal energy is released. The basis of the nutrition of beneficial bacteria is the remains of undigested food.

Dysbacteriosis

Dysbacteriosis is commonly referred to as changes in the quantity and quality of bacteria. In this case, a large number of good bacteria simply die, and the bad ones begin to multiply rapidly. Dysbacteriosis in many cases covers not only the intestines. It can manifest itself in the oral cavity or on the mucous membranes. In the analyzes, strepto- and staphylococci can be detected.

In the normal state of the body, beneficial bacteria are able to fully regulate the reproduction of pathogens. Usually the airways and skin are protected. But in the event of an imbalance, a person begins to feel some symptoms of a developing disease. There is pain in the abdomen, bloating, flatulence and diarrhea may develop. Later, beriberi, anemia begin. Due to lack of appetite, weight is rapidly reduced. Women may develop sexual dysfunction. There are copious vaginal discharges. Often they have an unpleasant odor. The skin becomes dry. On it you can find roughness and cracks. In almost all cases, dysbacteriosis is one of the manifestations of long-term use of antibiotics.

At the first signs of the disease, it is advisable to immediately consult a doctor. The doctor will prescribe all the necessary examinations, on the basis of which the most effective treatment for dysbacteriosis will be determined. Most often, various probiotics are used for medicinal purposes.

In the human body, there are many types of bacteria, among which useful, pathogenic and conditionally pathogenic forms stand out. Consider the features of the development of microbes, the diseases they provoke and the methods of infection by pathogens.

There is an opinion that the number of bacteria in the human body exceeds the volume of its own cells by 10 times. However, recent studies have questioned this figure. According to new materials, it varies from 1.5 to 2. In total, there are about 10 thousand species of bacteria that have adapted to living in various conditions.

They enter the human body from the environment in which they can persist for a long time. Pathogenic forms are causative agents of diseases that manifest themselves in varying degrees of intensity and danger. It can be either a mild skin rash or a serious infectious manifestation that poses a threat to the patient's life.

Bacteria appeared on Earth about 3.5 billion years ago. Their structure differs slightly from modern species. All bacteria are prokaryotes, which means that they do not have a nucleus in their cell. Outside, they are surrounded by a cell wall that retains the shape of the microorganism. Some species are able to produce a mucus that looks like a capsule and protects the microbe from drying out. There are forms that can actively move with the help of special flagella.

The internal structure of bacteria is quite simple. The cell contains the main inclusions:

• cytoplasm, which is 75% water, and the remaining 25% are minerals;
• granules, which are a source of energy for the body;
• mesosomes necessary for cell division and sporulation;
• nucleoid containing genetic information and acting as a nucleus;
• ribosomes involved in protein synthesis;
• plasmids.

The shape of bacterial cells can be spherical, rod-shaped, convoluted or club-shaped. They can be located singly or in groups. In this case, diplococci (in pairs), streptococci (in the form of chains), staphylococci (in the form of a grapevine) and sarcins (placement in a package) are isolated. Some rod-shaped bacteria form spores when exposed to adverse conditions. Such species are called bacilli.

All microorganisms reproduce by dividing the cell in two. Moreover, the rate of population increase can be as little as 20 minutes. Such a high reproduction rate is observed on food products and other nutrient substrates.

Beneficial bacteria living in the human body

The main representatives of beneficial microflora include:

1. Bifidobacteria. They live mainly in the large intestine, where they are involved in the activation of parietal digestion. In the process of life, they form a natural biological barrier that prevents the penetration of pathogens and toxins. In addition, they produce special acids that suppress the reproduction of pathogenic and opportunistic forms. Without the participation of bifidobacteria, the synthesis of B and K vitamins does not occur, as well as the absorption of iron and calcium.
2. Lactobacilli in the process of life form lactase, which breaks down milk sugar. Due to the production of lactic acid, they maintain the necessary level of acidity in the intestines, and also accelerate the healing of affected areas of the gastrointestinal tract. By analogy with bifidobacteria, they stimulate the immune system by activating the process of phagocytosis.

These microbes stand guard over the digestive tract, protecting it from useless microorganisms that can settle in the stomach and worsen a person's condition.

Normal human microflora should contain both types of microorganisms. Moreover, the number of bifidobacteria can be up to 95% of the total biocenosis of the body, and lactobacilli - only 5%. In this case, the latter live mainly in the vagina and oral cavity.

Bifido- and lactobacilli are part of the preparations used to normalize the human microflora. They are called probiotics, and in addition to these microorganisms contain propionic acid species, thermophilic streptococci and lactococci. Combined drugs are often prescribed for dysbacteriosis, antibiotic treatment, as well as any helminthic invasions.

To maintain optimal levels of beneficial bacteria, you need to eat certain foods. They should consist of components that are not digested in the upper intestines, thereby stimulating the reproduction of beneficial microbes. Such products include raw vegetables, dairy products, bran, cereals, berries, dried fruits.

Pathogenic forms of corynebacteria

Microorganisms of the genus Corynebacterium are Gram-positive bacteria with a rod-shaped body. Most representatives live in nature and do not pose a threat to human health. However, several species are causative agents of serious diseases requiring inpatient treatment.

Corynebacterium diphtheriae are slightly curved rods with a thickening on one side of the cell. Their size ranges from 0.1 to 8 microns. As the name suggests, the bacterium is the cause of diphtheria. Symptoms of the disease depend on the location of the pathogen. It can be the oral cavity, nose, larynx, trachea, bronchi, genitals, skin. Poisoning of the human body occurs due to the release of a special substance by bacteria called exotoxin. Its accumulation leads to fever, fever, headache, nausea, discomfort in the throat, swollen lymph nodes.

Another species of Corynebacterium minutissimum provokes the development of dermatological diseases. One of them is erythrasma, which occurs only in adults. It manifests itself in the form of rashes on the surface of the skin folds: inguinal-scrotal, between the buttocks, sometimes in the interdigital zones. Lesions have the appearance of brown spots of a non-inflamed structure, which may be the cause of mild itching. The bacterium survives well on household items, including phones and tablets.

Corynebacteria are also part of the normal microflora of the human large intestine. Non-pathogenic forms are actively used in industry for the production of amino acids, enzymes, and cheeses. Corynebacterium glutamicum is used in the production of glutamic acid, which is known as food additive E620.

Streptomycetes, their significance for humans

The genus Streptomyces includes spore-forming species that live primarily in the soil. They form chains of cells and resemble fungal mycelium in shape. In the process of life, special volatile substances are released, which give the earth a characteristic damp smell. A necessary condition for the existence of streptomycetes is the presence of molecular oxygen.

Many species are capable of producing valuable medicinal substances belonging to the group of antibiotics (streptomycin, erythromycin). In earlier periods, streptomycetes were used to produce:

• Physostigmine, used as an analgesic for increased eye pressure;
• Tacrolimus, necessary for prophylaxis during kidney, liver and bone marrow transplantation;
• Allosamidin, which is active against insects and fungi.

Streptomyces bikiniensis is a pathogenic form that provokes the development of bacteremia. With this disease, bacteria enter the bloodstream and can spread throughout the body.

Helicobacter pylori as a harmful bacterium

Helicobacter pylori has a spiral-shaped cell up to 3 microns in size. It is able to actively move even in thick mucus with the help of flagella. The bacterium infects various parts of the stomach and duodenum, causing the disease helicobacter pylori. The cause of ulcers and gastritis very often becomes this type of microbe.

Helicobacter is fixed on the surface of the gastric mucosa, damaging it and provoking the development of the inflammatory process. Infection with a bacterium manifests itself in the form of recurring severe pain in the stomach, which subsides after eating. Heartburn, nausea, vomiting, poor digestibility of meat dishes are also symptoms of the disease.

There is an opinion that Helicobacter pylori is part of the normal human microflora, and the pathological condition occurs with an increase in its number. At the same time, about 50 strains of this bacterium live in the stomach of people, of which only 5 pose a health hazard. In the case of the appointment of antibiotics, all individuals of the microorganism, including harmless ones, are destroyed.

Escherichia coli as a representative of the natural human microflora

E. coli refers to rod-shaped bacteria that play an important role in the functioning of the gastrointestinal tract. They can exist for a long time in the environment, including soil, water and faeces. Microorganisms quickly die when boiled and exposed to chlorine solutions. Bacteria actively multiply on food products, especially in milk.

Escherichia coli is able to absorb oxygen from the intestinal lumen, thereby protecting beneficial lactobacteria and bifidobacteria from destruction. In addition, it is involved in the production of B vitamins, fatty acids, and also affects the absorption of iron and calcium by the intestines. Normally, the content of bacteria in human feces should be no more than 108 CFU / g. Exceeding this indicator indicates the development of dysbacteriosis against the background of the inflammatory process in the body.

Pathogenic forms can cause infectious diseases of the gastrointestinal tract, accompanied by intoxication and fever. Enteropathogenic strains of Escherichia coli develop in the small intestine of newborns and cause severe diarrhea. In women, if intimate hygiene is not observed, bacteria can enter the genitourinary organs, provoking the development of bacteriuria.

Dangerous bacterium Staphylococcus aureus

Staphylococcus aureus belongs to the immobile spherical microbes of the genus Staphylococcus. Cells may be singly, in pairs or in clusters. Due to the content of pigments of the carotenoid group, the bacterium has a golden color, which is noticeable when studied under a microscope. Staphylococcus aureus is characterized by increased tolerance to high temperatures, light and chemicals.

The microorganism is the cause of the appearance of purulent-inflammatory foci of infection in humans. The main areas of pathogen localization include the nasal passages and axillary areas. However, cases of damage to the larynx and gastrointestinal tract are not uncommon. The bacterium is widespread in medical facilities. About 30% of patients after hospitalization are carriers of Staphylococcus aureus.

The main symptoms of infection with a pathogen include fever, lethargy, nausea, and lack of appetite. When the skin is damaged, small blisters form, resembling burns, which eventually turn into open wounds. Rhinitis, tonsillitis, pharyngitis, pneumonia can develop with the spread of the pathogen in the respiratory tract. Frequent and painful urination and back pain indicate the localization of staphylococcus aureus in the urethra.

Pseudomonas aeruginosa as one of the pathogenic species of bacteria

The bacterium belongs to mobile flagellar microorganisms, its main habitat is soil and water. In the process of life, it colors the food environment in a blue-green color, which is the reason for its name. It is highly resistant to antibiotics.

Pseudomonas aeruginosa is dangerous for immunocompromised people and is usually a nosocomial infection. Infection is possible through household items, towels, untreated medical instruments. An increased accumulation of the microorganism is observed on the wound surface and in the depths of purulent skin areas.

Pseudomonas aeruginosa can develop in:

• ENT organs and be accompanied by otitis, sinusitis;
• urinary tract with the appearance of urethritis, cystitis;
• soft tissues;
• intestines, causing dysbacteriosis, enteritis, colitis.

Bacteria, along with viruses, are the causative agents of numerous diseases that are not always treatable. The variety of species and their rapid adaptation to the effects of medical drugs make microbes a serious threat to human health. However, in most cases, infection can be avoided if you follow the rules of personal hygiene and strengthen the immune system.

Bacteria are very small, incredibly ancient, and to some extent quite simple microorganisms. According to the modern classification, they were identified as a separate domain of organisms, which indicates a significant difference between bacteria and other life forms.

Bacteria are the most common and, accordingly, the most numerous living organisms, they are, without exaggeration, ubiquitous and feel great in any environment: water, air, earth, as well as inside other organisms. So in one drop of water, their number can reach several million, and in the human body there are about ten more of them than all of our cells.

Who are bacteria?

These are microscopic, predominantly unicellular organisms, the main difference of which is the absence of a cell nucleus. The basis of the cell, the cytoplasm, contains ribosomes and a nucleoid, which is the genetic material of bacteria. All this is separated from the outside world by a cytoplasmic membrane or plasmalemma, which in turn is covered with a cell wall and a denser capsule. Some types of bacteria have external flagella, their number and size can vary greatly, but the purpose is always the same - with their help, the bacteria move.

Structure and contents of a bacterial cell

What are bacteria?

Shapes and sizes

The shapes of different types of bacteria are very variable: they can be round, rod-shaped, convoluted, stellate, tetrahedral, cubic, C- or O-shaped, and also irregular.

Bacteria vary greatly in size. So, Mycoplasma mycoides - the smallest species in the whole kingdom has a length of 0.1 - 0.25 micrometers, and the largest bacterium Thiomargarita namibiensis reaches 0.75 mm - it can even be seen with the naked eye. On average, the sizes range from 0.5 to 5 microns.

Metabolism or metabolism

In matters of obtaining energy and nutrients, bacteria exhibit extreme diversity. But at the same time, it is quite easy to generalize them, dividing them into several groups.

According to the method of obtaining nutrients (carbons), bacteria are divided into:

• autotrophs- organisms capable of independently synthesizing all the organic substances they need for life;
• heterotrophs- organisms that are able to transform only ready-made organic compounds, and therefore need the help of other organisms that would produce these substances for them.

By way of obtaining energy:

• phototrophs organisms that produce energy through photosynthesis
• chemotrophs- Organisms that produce energy through various chemical reactions.

How do bacteria reproduce?

Growth and reproduction in bacteria are closely related. Having reached a certain size, they begin to multiply. In most types of bacteria, this process can proceed extremely quickly. Cell division, for example, can take less than 10 minutes, while the number of new bacteria will grow exponentially, since each new organism will be divided into two.

There are 3 different types of reproduction:

• division- one bacterium is divided into two absolutely genetically identical.
• budding- one or more buds (up to 4) are formed at the poles of the parent bacterium, while the mother cell ages and dies.
• primitive sexual process- part of the DNA of the parent cells is transferred to the daughter, and a bacterium appears with a fundamentally new set of genes.

The first type is the most common and fastest, the last one is incredibly important, not only for bacteria, but for all life in general.

They surround us everywhere. Many of them are very necessary and useful for a person, and many, on the contrary, cause terrible diseases.
Do you know what forms bacteria come in? And how do they reproduce? And what do they eat? Do you want to know?
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Shapes and sizes of bacteria

Most bacteria are unicellular organisms. They differ in a wide variety of forms. Bacteria are given names based on their shape. For example, round-shaped bacteria are called cocci (all known streptococci and staphylococci), rod-shaped bacteria are called bacilli, pseudomonads or clostridia (the famous bacteria of this shape include the famous tuberculosis bacillus or Koch's wand). Bacteria can be shaped like spirals, then their names spirochetes, vibrils or spirilla. Not so often, but there are bacteria in the form of stars, different polygons or other geometric shapes.

Bacteria are not at all large, ranging in size from half to five micrometers. The largest bacterium has a size of seven hundred and fifty micrometers. After the discovery of nanobacteria, it turned out that their size is much smaller than previously imagined by scientists. However, to date, nanobacteria have not been well studied. Some scientists even doubt their existence.

Aggregates and multicellular organisms

Bacteria can attach to each other with the help of mucus, forming cell aggregates. At the same time, each individual bacterium is a self-sufficient organism, the vital activity of which does not depend in any way on relatives glued to it. Sometimes it happens that bacteria stick together in order to carry out some common function. Some bacteria, as a rule, of a filamentous form, can also form multicellular organisms.

How do they move?

There are bacteria that themselves are not able to move, but there are also those that are equipped with special devices for movement. Some bacteria move with the help of flagella, while others can glide. How bacteria glide is not yet fully understood. It is believed that bacteria secrete a special mucus that facilitates sliding. And then there are bacteria that can "dive". In order to descend into the depth of any liquid medium, such a microorganism can change its density. In order for a bacterium to start moving in any direction, it must be irritated.

Nutrition

There are bacteria that can only feed on organic compounds, and there are those that can process inorganics into organics and only then use them for their own needs. Bacteria obtain energy in three ways: using respiration, fermentation or photosynthesis.

reproduction

Regarding the reproduction of bacteria, we can say that it also does not differ in uniformity. There are bacteria that do not divide into sexes and multiply by simple division or budding. Some cyanobacteria have the ability to multiple division, that is, at one time they can produce up to a thousand "newborn" bacteria. There are also bacteria that reproduce sexually. Of course, they all do it in a very primitive way. But at the same time, two bacteria transfer their genetic data to the new cell - this is the main feature of sexual reproduction.

Bacteria, of course, deserve your attention, not only because they cause a lot of diseases. These microorganisms were the first living things to inhabit our planet. The history of bacteria on Earth goes back nearly four billion years! Cyanobacteria are the most ancient of the existing ones today, they appeared three and a half billion years ago.

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Everyone knows that bacteria are the most ancient species of living beings 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 products, plants. Just like humans, bacteria can be good or bad.

Beneficial bacteria are:

• Lactic acid or lactobacilli. One such good bacteria is lactic acid bacterium. It is a rod-shaped species of bacteria that lives in dairy and sour-milk foods. Also, these bacteria inhabit the human oral cavity, its intestines, and vagina. The main benefit of these bacteria is that they form 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 purifying the intestinal environment from bad bacteria.
• bifidobacteria. Bifidobacteria are found mainly in the gastrointestinal tract, as well as lactic acid bacteria are able to produce lactic acid and acetic acid, thanks 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, fungal infections.
• coli. The human intestinal microflora consists of most of the microbes of the E. coli group. They contribute to good digestion, and are also involved in some cellular processes. But some varieties of this stick can cause poisoning, diarrhea, kidney failure.
• Streptomycetes. The habitat of streptomycetes is water, decomposing compounds, soil. Therefore, they are especially useful for the environment, because. many processes of decay and combination 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 that enter the body are the causative agents of many diseases, such as tonsillitis, bronchitis, otitis media and others.
• Plague wand. The rod-shaped bacterium that lives in small rodents causes such terrible diseases as plague or pneumonia. Plague is a terrible disease that can destroy entire countries, and it is 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.
• Staphylococci. The name staphylococcus comes from the fact that the shape of the cells resembles a bunch of grapes. For humans, these bacteria carry serious diseases with intoxication and purulent formations. No matter how terrible bacteria are, humanity has learned to survive among them thanks to vaccination.