Good and bad bacteria. The structure of bacteria

The entire collection of bacteria that live in the human body is called 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 imbalanced and there is a shortage of any bacteria, this leads to disruptions in the functioning of the gastrointestinal tract. The disease-causing 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 required amount of beneficial bacteria.

The microflora of the human body is inhabited by both beneficial and pathogenic organisms. At 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 good microflora accounts for more than 95 percent of all microorganisms. There are such types of bacteria that live in the human body:

• lactobacilli;
• bifidobacteria;
• enterococci;
• Escherichia 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 disease-causing 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 takes part 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.

Lactobacillus

These microorganisms also play a rather important role in the normal functioning of the body. They are able to interact with other good bacteria in the gut. 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. The deficiency of these bacteria almost always leads to the development of dysbiosis.

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 a condition such as bacterial vaginosis.

Enterococci

Appear in the human body in the first days after birth. Promotes 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 microorganism is usually referred to as conditionally safe. If their concentration is exceeded, intestinal diseases develop.

Colibacillus

Many types of such microorganisms do not contribute to the development of any disease. 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 is involved in the synthesis of many vitamins, as well as niacin and folic acid. This is very important because folate is responsible for the production of red blood cells in the body, which helps maintain hemoglobin levels.

The positive effects of bacteria on the human body

Good bacteria have many useful and desirable 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 being exposed to beneficial bacteria. Because of this, the level of hemoglobin in the blood may decrease, the skin suffers, and disorders of the nervous system are observed.

The 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 takes part in the formation of local immunity. Helps block the growth of pathogenic microorganisms. Therefore, people do not feel bloating and flatulence. The increase in the number of lymphocytes provokes the work of phagocytes, which is to fight harmful microbes. Moreover, 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. Intestinal motility 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 general balance of the body is maintained by biochemical reactions that take place in the body with the participation of bacteria. This releases heat energy. The basis of nutrition for beneficial bacteria is the remnants of undigested food.

Dysbacteriosis

Dysbacteriosis is usually called 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 mouth or mucous membranes. In the analyzes, streptococci and staphylococci can be detected.

In the normal state of the body, beneficial bacteria are able to completely 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 of the symptoms of a developing disease. There is pain in the abdomen, bloating, possibly the development of flatulence and diarrhea. Later, vitamin deficiency and anemia begin. Due to lack of appetite, weight is rapidly reduced. Women can develop sexual disorders. Profuse vaginal discharge appears. They often have an unpleasant odor. The skin becomes dry. On it you can find roughness and cracks. In almost all cases, dysbiosis is one of the manifestations of long-term antibiotic use.

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 of dysbiosis will be determined. Most often, various probiotics are used for medicinal purposes.

The human body is inhabited by many types of bacteria, among which useful, pathogenic and opportunistic forms are distinguished. Consider the features of the development of microbes, the diseases they provoke and the methods of infection with pathogens.

It is believed 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 indicator. According to new materials, it varies in the range 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 is slightly different from modern species. All bacteria belong to prokaryotes, which means that their cell lacks a formed nucleus. Outside, they are surrounded by a cell wall, which retains the shape of the microorganism. Some species are capable of producing a capsule-like mucus that 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:

• the 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;
• a 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 clavate. They can be located singly or in groups. In this case, diplococci (pairwise arrangement), streptococci (in the form of chains), staphylococci (in the form of a vine) and sarcins (placement in a package) are isolated. Some rod-shaped bacteria form spores when exposed to unfavorable conditions. Such species are called bacilli.

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

Beneficial bacteria that live in the human body

The main representatives of useful 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 vitamins of group B and K does not occur, as well as the absorption of iron and calcium.
2. Lactobacilli in the process of their vital activity 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 the affected areas of the gastrointestinal tract. By analogy with bifidobacteria, they stimulate the immune system by activating the process of phagocytosis.

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

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

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

To maintain optimal levels of beneficial bacteria, you must eat certain foods. They should be composed of ingredients that are not digested in the upper intestine, thereby stimulating the growth of beneficial microbes. These 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 of the representatives live in nature and do not pose a threat to human health. However, several species are causative agents of serious diseases that require hospital 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, a bacterium is responsible for the development of diphtheria. Symptoms of the disease depend on the location of the pathogen. This can be the mouth, nose, larynx, trachea, bronchi, genitals, skin. Poisoning of the human body occurs due to the release of a special substance called exotoxin by bacteria. Its accumulation leads to fever, fever, headache, nausea, discomfort in the throat, swollen lymph nodes.

Another type 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. The lesions appear as brown spots of a non-inflamed structure, which can cause mild itching. The bacterium persists 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 the food additive E620.

Streptomycetes, their significance for humans

The genus Streptomyces includes spore-forming species that live predominantly in the soil. They form chains of cells and resemble the shape of the mycelium of fungi. In the process of vital activity, special volatile substances are emitted, 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 a pain reliever for increased eye pressure;
• Tacrolimus, necessary for prophylaxis in kidney, liver and bone marrow transplants;
• Allosamidine, 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 bacteria

Helicobacter pylori has a spiral-shaped cell up to 3 microns in size. She 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 the appearance of ulcers and gastritis is very often 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 the bacterium manifests itself in the form of repeated severe pain in the stomach area, which subside 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 state 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 are dangerous to health. In the case of the appointment of antibiotics, all individuals of the microorganism are destroyed, including harmless ones.

Escherichia coli as a representative of natural human microflora

Escherichia coli is a rod-shaped bacteria that plays 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 are quickly killed by boiling and exposure to chlorine solutions. Bacteria proliferate on food, especially milk.

Escherichia coli is able to absorb oxygen from the intestinal lumen, thereby protecting beneficial lacto- 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. An excess of this indicator indicates the development of dysbiosis against the background of an inflammatory process in the body.

Pathogenic forms can be the cause of infectious diseases of the gastrointestinal tract, accompanied by intoxication and fever. Enteropathogenic strains of E. 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 bacteria Staphylococcus aureus

Staphylococcus aureus belongs to the immobile spherical microbes of the genus Staphylococcus. Cells can be arranged 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 examined under a microscope. Staphylococcus aureus is highly resistant to heat, light and chemicals.

The microorganism is the cause of the appearance of purulent-inflammatory foci of infection in humans. The main areas of localization of the pathogen include the nasal passages and axillary regions. However, there are frequent cases of damage to the larynx and gastrointestinal tract. The bacterium is widespread in healthcare facilities. About 30% of patients after hospitalization are carriers of Staphylococcus aureus.

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

Pseudomonas aeruginosa as one of the pathogenic types of bacteria

The bacterium belongs to mobile flagellate microorganisms, its main habitat is soil and water. In the process of life, it colors the nutritional environment in a blue-green color, which is the reason for its name. Differs in high resistance to drugs from the group of antibiotics.

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

Pseudomonas aeruginosa can develop in:

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

Bacteria, along with viruses, are the causative agents of numerous diseases that are not always treatable. The diversity of species and their rapid adaptation to the effects of medications make microbes a serious threat to human health. However, in most cases, infection can be avoided by following the rules of personal hygiene and strengthening the immune system.

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

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 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 bacteria move.

The structure and content of a bacterial cell

What are bacteria?

Shapes and sizes

The forms in different types of bacteria are very variable: they can be round, rod-shaped, convoluted, stellate, tetrahedral, cubic, C- or O-shaped, as well as irregular.

Bacteria vary in size even more. 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 be seen even with an unarmed eye. On average, sizes range from 0.5 to 5 microns.

Metabolism or metabolism

Bacteria are extremely diverse when it comes to obtaining energy and nutrients. 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 necessary for their vital activity;
• heterotrophs- organisms capable of transforming only ready-made organic compounds, and therefore needing the help of other organisms that would produce these substances for them.

By the method of obtaining energy:

• phototrophs- organisms that produce the necessary energy as a result of photosynthesis
• chemotrophs- organisms that generate energy by carrying out various chemical reactions.

How do bacteria grow?

Growth and reproduction in bacteria are closely related. Having reached a certain size, they begin to reproduce. In most bacterial species, this process can be extremely fast. Cell division, for example, can take less than 10 minutes, with the number of new bacteria growing exponentially as each new organism divides in two.

There are 3 different types of breeding:

• division- one bacterium is divided into two absolutely genetically identical.
• budding- at the poles of the maternal bacterium, one or more buds (up to 4) are formed, while the maternal cell grows old and dies.
• primitive sexual process- a part of the DNA of the parental 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 is incredibly important, and not only for bacteria, but for all life in general.

Surround us everywhere. Many of them are very necessary and useful to humans, but many, on the contrary, cause terrible diseases.
Do you know what forms bacteria are? How do they reproduce? And what do they eat? Do you want to know?
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The shapes and sizes of bacteria

Most bacteria are single celled organisms. They are distinguished by a wide variety of shapes. The bacteria are named depending on the shape. For example, round-shaped bacteria are called cocci (well-known streptococci and staphylococci), bacteria in the form of sticks are called bacilli, pseudomonads or clostridia (the famous tubercle bacillus or Koch's wand). Bacteria can be in the form of spirals, then their names spirochetes, vibrils or spirilla... Not so often, but bacteria in the form of stars, various polygons or other geometric shapes do occur.

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

Aggregates and multicellular organisms

Bacteria can attach to each other using mucus, forming cell aggregates. Moreover, each individual bacterium is a self-sufficient organism, the vital activity of which does not depend in any way on the congeners glued to it. Sometimes it happens that bacteria stick together in order to carry out some common function. Some bacteria, usually filamentous, can 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 slide. How bacteria slide is not yet fully understood. It is believed that bacteria secrete a special mucus that makes sliding easier. And then there are bacteria that can "dive". In order to descend into the depths of any liquid medium, such a microorganism can change its density. In order for the bacterium to start moving in some direction, it must get irritated.

Nutrition

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

Reproduction

Regarding the multiplication 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 multiply, 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 this very primitively. But at the same time, two bacteria transfer their genetic data to the new cell - this is the main feature of sexual reproduction.

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

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

Good bacteria are:

• Lactic acid or lactobacilli... One of these good bacteria is lactic acid bacteria. It is a rod-shaped species of bacteria that lives in dairy and fermented milk products. Also, these bacteria inhabit the human oral cavity, intestines, and vagina. The main benefit of these bacteria is that they form lactic acid as 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 cleansers of the intestinal environment from bad bacteria.
• Bifidobacteria... Bifidobacteria are found mainly in the gastrointestinal tract, as lactic acid is 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 types of bifidobacteria help get rid of constipation, diarrhea, fungal infections.
• Colibacillus... The human intestinal microflora consists of most of the microbes of the E. coli group. They promote good digestion and are also involved in several cellular processes. But some varieties of this bacillus 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 decay and compounds 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... Chained bacteria that enter the body are the causative agents of many diseases, such as tonsillitis, bronchitis, otitis media and others.
• Plague wand... A 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 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.
• Staphylococci... The name Staphylococcus aureus comes from the fact that the cells are shaped like a bunch of grapes. For humans, these bacteria carry severe diseases with intoxication and purulent formations. No matter how terrible the bacteria are, humanity has learned to survive among them thanks to vaccination.