BACTERIA
a large group of unicellular microorganisms characterized by the absence of a cell nucleus surrounded by a membrane. At the same time, the genetic material of the bacterium (deoxyribonucleic acid, or DNA) occupies a very specific place in the cell - a zone called the nucleoid. Organisms with such a cell structure are called prokaryotes (“prenuclear”), in contrast to all others - eukaryotes (“true nuclear”), whose DNA is located in the nucleus surrounded by a shell. Bacteria, previously considered microscopic plants, are now classified into the independent kingdom Monera - one of five in the current classification system, along with plants, animals, fungi and protists.
Fossil evidence. Bacteria are probably the oldest known group of organisms. Layered stone structures - stromatolites - dated in some cases to the beginning of the Archeozoic (Archean), i.e. arose 3.5 billion years ago, - the result of the vital activity of bacteria, usually photosynthesizing, the so-called. blue-green algae. Similar structures (bacterial films impregnated with carbonates) are still formed today, mainly off the coast of Australia, the Bahamas, in the California and Persian Gulfs, but they are relatively rare and do not reach large sizes, because herbivorous organisms, such as gastropods, feed on them. Nowadays, stromatolites grow mainly where these animals are absent due to high salinity of water or for other reasons, but before the emergence of herbivorous forms during the evolution, they could reach enormous sizes, constituting an essential element of oceanic shallow water, comparable to modern coral reefs.
In some ancient rocks, tiny charred spheres have been found, which are also believed to be the remains of bacteria. The first nuclear ones, i.e. eukaryotic, cells evolved from bacteria approximately 1.4 billion years ago. Ecology. There are many bacteria in the soil, at the bottom of lakes and oceans - wherever they accumulate. They live in the cold, when the thermometer is just above zero, and in hot acidic springs with temperatures above 90 ° C. Some bacteria tolerate very high salinity; in particular, they are the only organisms found in the Dead Sea. In the atmosphere, they are present in water droplets, and their abundance there usually correlates with the dustiness of the air. Yes, in cities rainwater contains much more bacteria than in rural areas. There are few of them in the cold air of high mountains and polar regions, however, they are found even in the lower layer of the stratosphere at an altitude of 8 km. The digestive tract of animals is densely populated with bacteria (usually harmless). Experiments have shown that they are not necessary for the life of most species, although they can synthesize some vitamins. However, in ruminants (cows, antelopes, sheep) and many termites, they are involved in the digestion of plant food. Additionally, the immune system of an animal raised under sterile conditions does not develop normally due to lack of bacterial stimulation. The normal bacterial "flora" of the intestines is also important for suppressing intestinal harmful microorganisms.
STRUCTURE AND LIFE ACTIVITY OF BACTERIA
Bacteria are much smaller than the cells of multicellular plants and animals. Their thickness is usually 0.5-2.0 microns, and their length is 1.0-8.0 microns. Some forms are barely visible at the resolution of standard light microscopes (approximately 0.3 microns), but species are also known with a length of more than 10 microns and a width that also goes beyond the specified limits, and a number of very thin bacteria can exceed 50 microns in length. On the surface corresponding to the point marked with a pencil, a quarter of a million medium-sized representatives of this kingdom will fit.
Structure. Based on their morphological features, the following groups of bacteria are distinguished: cocci (more or less spherical), bacilli (rods or cylinders with rounded ends), spirilla (rigid spirals) and spirochetes (thin and flexible hair-like forms). Some authors tend to combine the last two groups into one - spirilla. Prokaryotes differ from eukaryotes mainly in the absence of a formed nucleus and the typical presence of only one chromosome - a very long circular DNA molecule attached at one point to the cell membrane. Prokaryotes also do not have membrane-enclosed intracellular organelles called mitochondria and chloroplasts. In eukaryotes, mitochondria produce energy during respiration, and photosynthesis occurs in chloroplasts (see also CELL). In prokaryotes, the entire cell (and primarily the cell membrane) takes on the function of a mitochondrion, and in photosynthetic forms, it also takes on the function of a chloroplast. Like eukaryotes, inside bacteria there are small nucleoprotein structures - ribosomes, necessary for protein synthesis, but they are not associated with any membranes. With very few exceptions, bacteria are unable to synthesize sterols, important components of eukaryotic cell membranes. Outside the cell membrane, most bacteria are covered with a cell wall, somewhat reminiscent of the cellulose wall of plant cells, but consisting of other polymers (they include not only carbohydrates, but also amino acids and bacteria-specific substances). This membrane prevents the bacterial cell from bursting when water enters it through osmosis. On top of the cell wall is often a protective mucous capsule. Many bacteria are equipped with flagella, with which they actively swim. Bacterial flagella are structured simpler and somewhat differently than similar structures of eukaryotes.
"TYPICAL" BACTERIAL CELL and its basic structures.
Sensory functions and behavior. Many bacteria have chemical receptors that detect changes in the acidity of the environment and the concentration of various substances, such as sugars, amino acids, oxygen and carbon dioxide. Each substance has its own type of such “taste” receptors, and the loss of one of them as a result of mutation leads to partial “taste blindness”. Many motile bacteria also respond to temperature fluctuations, and photosynthetic species respond to changes in light intensity. Some bacteria perceive the direction of field lines magnetic field, including the Earth’s magnetic field, with the help of particles of magnetite (magnetic iron ore - Fe3O4) present in their cells. In water, bacteria use this ability to swim along lines of force in search of a favorable environment. Conditioned reflexes bacteria are unknown, but they have a certain kind of primitive memory. While swimming, they compare the perceived intensity of the stimulus with its previous value, i.e. determine whether it has become larger or smaller, and, based on this, maintain the direction of movement or change it.
Reproduction and genetics. Bacteria reproduce asexually: the DNA in their cell is replicated (doubled), the cell divides in two, and each daughter cell receives one copy of the parent DNA. Bacterial DNA can also be transferred between non-dividing cells. At the same time, their fusion (as in eukaryotes) does not occur, the number of individuals does not increase, and usually only a small part of the genome (the complete set of genes) is transferred to another cell, in contrast to the “real” sexual process, in which the descendant receives a complete set of genes from each parent. This DNA transfer can occur in three ways. During transformation, the bacterium absorbs from environment“naked” DNA that got there during the destruction of other bacteria or was deliberately “slipped” by the experimenter. The process is called transformation because in the early stages of its study the main attention was paid to the transformation (transformation) of harmless organisms into virulent ones in this way. DNA fragments can also be transferred from bacteria to bacteria by special viruses - bacteriophages. This is called transduction. A process reminiscent of fertilization and called conjugation is also known: bacteria are connected to each other by temporary tubular projections (copulatory fimbriae), through which DNA passes from a “male” cell to a “female” one. Sometimes bacteria contain very small additional chromosomes - plasmids, which can also be transferred from individual to individual. If the plasmids contain genes that cause resistance to antibiotics, they speak of infectious resistance. She is important with medical point vision, since it can spread between different species and even genera of bacteria, as a result of which the entire bacterial flora, say, the intestines, becomes resistant to the action of certain medicines.
METABOLISM
Partly due to the small size of bacteria, their metabolic rate is much higher than that of eukaryotes. At the most favorable conditions some bacteria can double their total mass and number approximately every 20 minutes. This is explained by the fact that a number of their most important enzyme systems function with very high speed. Thus, a rabbit needs a matter of minutes to synthesize a protein molecule, while bacteria take seconds. However, in a natural environment, for example in soil, most bacteria are “on a starvation diet”, so if their cells divide, it is not every 20 minutes, but once every few days.
Nutrition. Bacteria are autotrophs and heterotrophs. Autotrophs (“self-feeding”) do not need substances produced by other organisms. As the main or single source carbon they use its dioxide (CO2). Including CO2 and other inorganic substances, in particular ammonia (NH3), nitrates (NO-3) and various connections sulfur into complex chemical reactions, they synthesize all the biochemical products they need. Heterotrophs (“feeding on others”) use organic (carbon-containing) substances synthesized by other organisms, in particular sugars, as the main source of carbon (some species also need CO2). When oxidized, these compounds supply energy and molecules necessary for cell growth and functioning. In this sense, heterotrophic bacteria, which include the vast majority of prokaryotes, are similar to humans.
Main sources of energy. If mainly light energy (photons) is used for the formation (synthesis) of cellular components, then the process is called photosynthesis, and species capable of it are called phototrophs. Phototrophic bacteria are divided into photoheterotrophs and photoautotrophs depending on which compounds - organic or inorganic - serve as their main source of carbon. Photoautotrophic cyanobacteria (blue-green algae), like green plants, break down water molecules (H2O) using light energy. This releases free oxygen (1/2O2) and produces hydrogen (2H+), which can be said to convert carbon dioxide (CO2) into carbohydrates. Green and purple sulfur bacteria use light energy to break down other inorganic molecules, such as hydrogen sulfide (H2S), rather than water. The result also produces hydrogen, which reduces carbon dioxide, but no oxygen is released. This type of photosynthesis is called anoxygenic. Photoheterotrophic bacteria, such as purple nonsulfur bacteria, use light energy to produce hydrogen from organic substances, in particular isopropanol, but their source can also be H2 gas. If the main source of energy in the cell is the oxidation of chemicals, the bacteria are called chemoheterotrophs or chemoautotrophs, depending on whether the molecules serve as the main source of carbon - organic or inorganic. For the former, organic matter provides both energy and carbon. Chemoautotrophs obtain energy from the oxidation of inorganic substances, such as hydrogen (to water: 2H4 + O2 to 2H2O), iron (Fe2+ to Fe3+) or sulfur (2S + 3O2 + 2H2O to 2SO42- + 4H+), and carbon from CO2. These organisms are also called chemolithotrophs, thereby emphasizing that they “feed” on rocks.
Breath. Cellular respiration is the process of releasing chemical energy stored in “food” molecules for its further use in vital reactions. Respiration can be aerobic and anaerobic. In the first case, it requires oxygen. It is needed for the work of the so-called. electron transport system: electrons move from one molecule to another (energy is released) and ultimately join oxygen along with hydrogen ions - water is formed. Anaerobic organisms do not need oxygen, and for some species of this group it is even poisonous. The electrons released during respiration attach to other inorganic acceptors, such as nitrate, sulfate or carbonate, or (in one form of such respiration - fermentation) to a specific organic molecule, in particular glucose. See also METABOLISM.
CLASSIFICATION
In most organisms, a species is considered to be a reproductively isolated group of individuals. In a broad sense, this means that representatives of a given species can produce fertile offspring by mating only with their own kind, but not with individuals of other species. Thus, the genes of a particular species, as a rule, do not extend beyond its boundaries. However, in bacteria, gene exchange can occur between individuals not only different types, but also of different genera, so whether it is legitimate to apply the usual concepts of evolutionary origin and kinship here is not entirely clear. Due to this and other difficulties, there is no generally accepted classification of bacteria yet. Below is one of the widely used variants.
KINGDOM OF MONERA
Phylum Gracilicutes (thin-walled gram-negative bacteria)
Class Scotobacteria (non-photosynthetic forms, such as myxobacteria) Class Anoxyphotobacteria (non-oxygen-producing photosynthetic forms, such as purple sulfur bacteria) Class Oxyphotobacteria (oxygen-producing photosynthetic forms, such as cyanobacteria)
Phylum Firmicutes (thick-walled gram-positive bacteria)
Class Firmibacteria (hard-celled forms, such as clostridia)
Class Thallobacteria (branched forms, e.g. actinomycetes)
Phylum Tenericutes (Gram-negative bacteria without a cell wall)
Class Mollicutes (soft-celled forms, such as mycoplasmas)
Phylum Mendosicutes (bacteria with defective cell walls)
Class Archaebacteria (ancient forms, e.g. methane-forming)
Domains. Recent biochemical studies have shown that all prokaryotes are clearly divided into two categories: a small group of archaebacteria (Archaebacteria - "ancient bacteria") and all the rest, called eubacteria (Eubacteria - "true bacteria"). It is believed that archaebacteria, compared to eubacteria, are more primitive and closer to the common ancestor of prokaryotes and eukaryotes. They differ from other bacteria in several significant features, including the composition of ribosomal RNA (rRNA) molecules involved in protein synthesis, the chemical structure of lipids (fat-like substances) and the presence in the cell wall of some other substances instead of the protein-carbohydrate polymer murein. In the above classification system, archaebacteria are considered only one of the types of the same kingdom, which unites all eubacteria. However, according to some biologists, the differences between archaebacteria and eubacteria are so profound that it is more correct to consider archaebacteria within Monera as a special subkingdom. Recently, an even more radical proposal has appeared. Molecular analysis has revealed such significant differences in gene structure between these two groups of prokaryotes that some consider their presence within the same kingdom of organisms to be illogical. In this regard, it is proposed to create a taxonomic category (taxon) of an even higher rank, calling it a domain, and divide all living things into three domains - Eucarya (eukaryotes), Archaea (archaebacteria) and Bacteria (current eubacteria).
ECOLOGY
The two most important ecological functions of bacteria are nitrogen fixation and mineralization of organic residues.
Nitrogen fixation. The binding of molecular nitrogen (N2) to form ammonia (NH3) is called nitrogen fixation, and the oxidation of the latter to nitrite (NO-2) and nitrate (NO-3) is called nitrification. These are vital processes for the biosphere, since plants need nitrogen, but they can only absorb its bound forms. Currently, approximately 90% (approx. 90 million tons) of the annual amount of such “fixed” nitrogen is provided by bacteria. The rest is produced by chemical plants or occurs during lightning strikes. Nitrogen in the air, which is approx. 80% of the atmosphere is bound mainly by the gram-negative genus Rhizobium and cyanobacteria. Rhizobium species enter into symbiosis with approximately 14,000 species of leguminous plants (family Leguminosae), which include, for example, clover, alfalfa, soybeans and peas. These bacteria live in the so-called. nodules - swellings formed on the roots in their presence. Bacteria obtain organic substances (nutrition) from the plant, and in return supply the host with fixed nitrogen. Over the course of a year, up to 225 kg of nitrogen per hectare is fixed in this way. Non-legume plants, such as alder, also enter into symbiosis with other nitrogen-fixing bacteria. Cyanobacteria photosynthesize, like green plants, releasing oxygen. Many of them are also capable of fixing atmospheric nitrogen, which is then consumed by plants and ultimately animals. These prokaryotes serve as an important source of fixed nitrogen in the soil in general and rice paddies in the East in particular, as well as its main supplier for ocean ecosystems.
Mineralization. This is the name given to the decomposition of organic residues into carbon dioxide (CO2), water (H2O) and mineral salts. From a chemical point of view, this process is equivalent to combustion, so it requires large amounts of oxygen. IN top layer soil contains from 100,000 to 1 billion bacteria per 1 g, i.e. approximately 2 tons per hectare. Typically, all organic residues, once in the ground, are quickly oxidized by bacteria and fungi. More resistant to decomposition is a brownish organic substance called humic acid, which is formed mainly from lignin contained in wood. It accumulates in the soil and improves its properties.
BACTERIA AND INDUSTRY
Given the variety of chemical reactions bacteria catalyze, it is not surprising that they have been widely used in manufacturing, in some cases since ancient times. Prokaryotes share the glory of such microscopic human assistants with fungi, primarily yeast, which provide most of the processes of alcoholic fermentation, for example, in the production of wine and beer. Now that it has become possible to introduce useful genes into bacteria, causing them to synthesize valuable substances such as insulin, the industrial application of these living laboratories has received a new powerful incentive. See also GENETIC ENGINEERING.
Food industry. Currently, bacteria are used by this industry mainly for the production of cheeses, other fermented milk products and vinegar. The main chemical reactions here are the formation of acids. Thus, when producing vinegar, bacteria of the genus Acetobacter oxidize ethyl alcohol contained in cider or other liquids to acetic acid. Similar processes occur when sauerkraut is sauerkraut: anaerobic bacteria ferment the sugars contained in the leaves of this plant to lactic acid, as well as acetic acid and various alcohols.
Ore leaching. Bacteria are used for leaching of low-grade ores, i.e. transferring them into a salt solution valuable metals, primarily copper (Cu) and uranium (U). An example is the processing of chalcopyrite, or copper pyrite (CuFeS2). Heaps of this ore are periodically watered with water, which contains chemolithotrophic bacteria of the genus Thiobacillus. During their life activity, they oxidize sulfur (S), forming soluble copper and iron sulfates: CuFeS2 + 4O2 in CuSO4 + FeSO4. Such technologies greatly simplify the extraction of valuable metals from ores; in principle, they are equivalent to the processes that occur in nature during the weathering of rocks.
Recycling. Bacteria also serve to convert waste materials, such as sewage, into less hazardous or even useful products. Wastewater- one of the most pressing problems of modern humanity. Their complete mineralization requires huge amounts of oxygen, and in ordinary reservoirs where it is customary to dump this waste, there is no longer enough oxygen to “neutralize” it. The solution lies in additional aeration of the wastewater in special pools (aeration tanks): as a result, the mineralizing bacteria have enough oxygen to completely decompose organic matter, and in the most favorable cases, one of the end products of the process becomes drinking water. The insoluble sediment remaining along the way can be subjected to anaerobic fermentation. So that such water treatment plants take away as much as possible less space and money, a good knowledge of bacteriology is necessary.
Other uses. Other important areas of industrial application of bacteria include, for example, flax lobe, i.e. separation of its spinning fibers from other parts of the plant, as well as the production of antibiotics, in particular streptomycin (bacteria of the genus Streptomyces).
COMBATING BACTERIA IN INDUSTRY
Bacteria are not only beneficial; The fight against their mass reproduction, for example in food products or in the water systems of pulp and paper mills, has become a whole area of activity. Food spoils under the influence of bacteria, fungi and its own enzymes that cause autolysis ("self-digestion"), unless they are inactivated by heat or other means. Because the main reason Since spoilage is still caused by bacteria, the development of effective food storage systems requires knowledge of the endurance limits of these microorganisms. One of the most common technologies is pasteurization of milk, which kills bacteria that cause, for example, tuberculosis and brucellosis. The milk is kept at 61-63°C for 30 minutes or at 72-73°C for only 15 seconds. This does not impair the taste of the product, but inactivates pathogenic bacteria. Wine, beer and fruit juices can also be pasteurized. The benefits of storing food in the cold have long been known. Low temperatures do not kill bacteria, but they do prevent them from growing and reproducing. True, when frozen, for example, to -25 ° C, the number of bacteria decreases after a few months, but a large number of these microorganisms still survive. At temperatures just below zero, bacteria continue to multiply, but very slowly. Their viable cultures can be stored almost indefinitely after lyophilization (freeze-drying) in a protein-containing medium, such as blood serum. Other known methods of storing food include drying (drying and smoking), adding large amounts of salt or sugar, which is physiologically equivalent to dehydration, and pickling, i.e. placing in a concentrated acid solution. When the acidity of the environment corresponds to pH 4 and below, the vital activity of bacteria is usually greatly inhibited or stopped.
BACTERIA AND DISEASES
STUDYING BACTERIA
Many bacteria are easy to grow in so-called. culture medium, which may include meat broth, partially digested protein, salts, dextrose, whole blood, its serum and other components. The concentration of bacteria in such conditions usually reaches about a billion per cubic centimeter, causing the environment to become cloudy. To study bacteria, it is necessary to be able to obtain their pure cultures, or clones, which are the offspring of a single cell. This is necessary, for example, to determine what type of bacteria infected the patient and what antibiotic this type is sensitive to. Microbiological samples, such as throat or wound swabs, blood samples, water samples or other materials, are highly diluted and applied to the surface of a semi-solid medium: on it, round colonies develop from individual cells. The hardening agent for the culture medium is usually agar, a polysaccharide obtained from certain seaweed and is not digestible by almost any type of bacteria. Agar media is used in the form of “shoals”, i.e. inclined surfaces formed in test tubes standing at a large angle when the molten culture medium solidifies, or in the form thin layers in glass Petri dishes - flat round vessels, closed with a lid of the same shape, but slightly larger in diameter. Usually, within a day, the bacterial cell manages to multiply so much that it forms a colony that is easily visible to the naked eye. It can be transferred to another environment for further study. All culture media must be sterile before growing bacteria, and in the future measures should be taken to prevent the settlement of unwanted microorganisms on them. To examine bacteria grown in this way, heat a thin wire loop in a flame, touch it first to a colony or smear, and then to a drop of water applied to a glass slide. Having evenly distributed the taken material in this water, the glass is dried and quickly passed over the burner flame two or three times (the side with the bacteria should be facing up): as a result, the microorganisms, without being damaged, are firmly attached to the substrate. Dye is dripped onto the surface of the preparation, then the glass is washed in water and dried again. Now you can examine the sample under a microscope. Pure cultures of bacteria are identified mainly by their biochemical characteristics, i.e. determine whether they form gas or acids from certain sugars, whether they are able to digest protein (liquefy gelatin), whether they need oxygen for growth, etc. They also check whether they are stained with specific dyes. Sensitivity to certain medications, such as antibiotics, can be determined by placing small disks of filter paper soaked in these substances on a surface infested with bacteria. If any chemical compound kills bacteria, a bacteria-free zone is formed around the corresponding disk.
Collier's Encyclopedia. - Open Society. 2000 .
Bacteria are very small, incredibly ancient and to some extent quite simple microorganisms. According to modern classification they were separated into a separate domain of organisms, which indicates a significant difference between bacteria and other forms of life.
Bacteria are the most common and, accordingly, the most numerous living organisms; they are, without exaggeration, omnipresent and thrive 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.
What are bacteria?
These are microscopic, predominantly single-celled 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 serves as 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 their purpose is always the same - they help bacteria move.
Structure and contents of a bacterial cell
What are bacteria?
Shapes and sizes
The shapes of different types of bacteria vary greatly: they can be round, rod-shaped, convoluted, stellate, tetrahedral, cubic, C- or O-shaped, or irregular.
Bacteria vary in size even more. Thus, Mycoplasma mycoides - the smallest species in the entire 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 the naked eye. On average, the sizes range from 0.5 to 5 microns.
Metabolism or metabolism
In matters of energy production and nutrients bacteria exhibit extreme diversity. But at the same time, it is quite easy to generalize them by dividing them into several groups.
According to the method of obtaining nutrients (carbons), bacteria are divided into:
- autotrophs- organisms that are capable of independently synthesizing all the organic substances they need for life;
- heterotrophs- organisms capable of transforming only ready-made ones organic compounds, and therefore need the help of other organisms to produce these substances for them.
By method of obtaining energy:
- phototrophs- organisms that produce the necessary energy as a result of photosynthesis
- chemotrophs- organisms that produce energy by carrying out various chemical reactions.
How do bacteria reproduce?
Growth and reproduction in bacteria are closely related. Having reached a certain size, they begin to reproduce. In most types of bacteria this process can occur extremely quickly. Cell division, for example, can occur in less than 10 minutes, and the number of new bacteria will grow exponentially as each new organism divides into two.
There are 3 different types of reproduction:
- division- one bacterium divides into two absolutely genetically identical ones.
- budding- one or more buds (up to 4) are formed at the poles of the mother bacterium, while the mother cell ages and dies.
- primitive sexual process- part of the DNA of the parent cells is transferred to the daughter cells, and a bacterium with a fundamentally new set of genes appears.
The first type is the most common and fastest, the latter is incredibly important, not only for bacteria, but for all life in general.
The beneficial bacteria that inhabit the human body are called microbiota. They are quite vast in number - one person has millions of them. Moreover, they all regulate the health and normal functioning of each individual. Scientists say: without beneficial bacteria, or, as they are also called, mutualists, the gastrointestinal tract, skin, and respiratory tract would instantly be attacked by pathogenic microbes and would be destroyed.
What should be the balance of microbiota in the body and how it can be adjusted to avoid the development of serious diseases, AiF.ru asked general director biomedical holding of Sergei Musienko.
Intestinal Workers
One of the important areas where beneficial bacteria are located is the intestines. It is not without reason that it is believed that this is where the entire human immune system is founded. And if the bacterial environment is disturbed, then the body’s defenses are significantly reduced.
Beneficial intestinal bacteria create literally unbearable living conditions for pathogenic microbes - an acidic environment. In addition, beneficial microorganisms help digest plant foods, since bacteria feed on plant cells containing cellulose, but intestinal enzymes cannot cope with this alone. Also, intestinal bacteria contribute to the production of vitamins B and K, which ensure metabolism in bones and connective tissues, as well as release energy from carbohydrates and promote the synthesis of antibodies and regulation of the nervous system.
Most often, when talking about beneficial intestinal bacteria, they mean the 2 most popular types: bifidobacteria and lactobacilli. At the same time, they cannot be called the main ones, as many people think - their number is only 5-15% of the total. However, they are very important, since their positive effect on other bacteria has been proven, when such bacteria can be important factors well-being of an entire community: if they are fed or introduced into the body with fermented milk products - kefir or yoghurt, they help other important bacteria survive and reproduce. For example, it is very important to restore their population during dysbacteriosis or after a course of antibiotics. Otherwise, it will be problematic to increase the body’s defenses.
Biological shield
The bacteria that inhabit the skin and respiratory tract of humans, in fact, stand guard and reliably protect their area of responsibility from the penetration of pathogenic organisms. The main ones are micrococci, streptococci and staphylococci.
The skin microbiome has undergone changes over the past hundreds of years, as humans have moved from a natural life in contact with nature to regular washing. by special means. It is believed that human skin is now inhabited by completely different bacteria that lived before. The body, with the help of the immune system, can distinguish dangerous from non-dangerous. But, on the other hand, any streptococcus can become pathogenic for a person, for example, if it gets into a cut or any other open wound on the skin. An excess of bacteria or their pathological activity on the skin and in the respiratory tract can lead to the development of various diseases, and to the appearance of an unpleasant odor. Today there are developments based on bacteria that oxidize ammonium. Their use makes it possible to seed the skin microbiome with completely new organisms, as a result of which not only the smell disappears (the result of the metabolism of urban flora), but also the structure of the skin changes - pores open, etc.
Saving the microworld
The microcosm of each person changes quite quickly. And this has undoubted advantages, since the number of bacteria can be updated independently.
Different bacteria feed on different substances - the more varied a person’s food and the more it corresponds to the season, the more choice beneficial microorganisms have. However, if food is heavily loaded with antibiotics or preservatives, bacteria will not survive, because these substances are precisely designed to destroy them. Moreover, it does not matter at all that most of the bacteria are not pathogenic. As a result, the diversity of a person’s inner world is destroyed. And after this, various diseases begin - problems with stool, skin rashes, metabolic disorders, allergic reactions, etc.
But the microbiota can be helped. Moreover, it will take only a few days for a slight correction.
There are a large number of probiotics (with live bacteria) and prebiotics (substances that support bacteria). But the main problem is that they work differently for everyone. Analysis shows that their effectiveness against dysbacteriosis is up to 70-80%, that is, one or another drug may work, or it may not. And here you should carefully monitor the progress of treatment and administration - if the remedies work, you will immediately notice improvements. If the situation remains unchanged, it is worth changing the treatment program.
Alternatively, you can undergo special testing that studies the genomes of bacteria, determines their composition and ratio. This allows you to quickly and competently select required option nutrition and additional therapy that will restore the fragile balance. Although a person does not feel slight disturbances in the balance of bacteria, they still affect health - in this case, frequent illnesses, drowsiness, and allergic manifestations can be noted. Every city resident, to one degree or another, has an imbalance in the body, and if he does not do anything specifically to restore it, then he will probably have health problems from a certain age.
Fasting, fasting, more vegetables, porridge from natural cereals in the morning - these are just a few of the eating habits that people love beneficial bacteria. But for each person, the diet should be individual in accordance with the state of his body and his lifestyle - only then can he maintain an optimal balance and always feel good.
Rice. 1. The human body consists of 90% microbial cells. It contains from 500 to 1000 different types of bacteria or trillions of these amazing residents, which amounts to up to 4 kg of total weight.
Rice. 2. Bacteria inhabiting oral cavity: Streptococcus mutants ( green color). Bakteroides gingivalis, causes periodontitis ( purple colour). Candida albicus ( yellow). Causes candidiasis of the skin and internal organs.
Rice. 7. Mycobacterium tuberculosis. Bacteria have been causing diseases in humans and animals for many millennia. The tuberculosis bacillus is extremely resistant to external environment. In 95% of cases it is transmitted by airborne droplets. Most often affects the lungs.
Rice. 8. The causative agent of diphtheria is corynebacteria or Loeffler's bacillus. It often develops in the epithelium of the mucous layer of the tonsils, less often in the larynx. Swelling of the larynx and enlarged lymph nodes can lead to asphyxia. The pathogen toxin is fixed on the membranes of the cells of the heart muscle, kidneys, adrenal glands and nerve ganglia and destroys them.
Rice. 9. Causative agents of staphylococcal infection. Pathogenic staphylococci cause extensive damage to the skin and its appendages, damage to many internal organs, foodborne toxic infection, enteritis and colitis, sepsis and toxic shock.
Rice. 10. Meningococci are the causative agents of meningococcal infection. Up to 80% of cases are children. The infection is transmitted by airborne droplets from sick and healthy carriers of bacteria.
Rice. 11. Bordetella pertussis.
Rice. 12. The causative agent of scarlet fever is streptococcus pyogenes.
Harmful bacteria of water microflora
Water is the habitat for many microbes. In 1 cm3 of water you can count up to 1 million microbial bodies. Pathogenic microorganisms enter water from industrial enterprises, settlements and livestock farms. Water containing pathogenic microbes can become a source dysentery, cholera, typhoid fever, tularemia, leptospirosis, etc. Vibrio cholerae and can remain in water for quite a long time.
Rice. 13. Shigella. Pathogens cause bacillary dysentery. Shigella destroys the epithelium of the colon mucosa, causing severe ulcerative colitis. Their toxins affect the myocardium, nervous and vascular systems.
Rice. 14. . Vibrios do not destroy the cells of the mucous layer of the small intestine, but are located on their surface. They secrete a toxin called choleragen, the action of which leads to disruption of water-salt metabolism, causing the body to lose up to 30 liters of fluid per day.
Rice. 15. Salmonella is the causative agent of typhoid fever and paratyphoid fever. Affects epithelium and lymphoid elements small intestine. With the bloodstream they enter the bone marrow, spleen and gall bladder, from which the pathogens again enter the small intestine. As a result of immune inflammation, the wall of the small intestine ruptures and peritonitis occurs.
Rice. 16. Causative agents of tularemia (blue coccobacteria). They affect the respiratory tract and intestines. They have the ability to penetrate the human body through intact skin and mucous membranes of the eyes, nasopharynx, larynx and intestines. The peculiarity of the disease is damage to the lymph nodes (primary bubo).
Rice. 17. Leptospira. They affect the human capillary network, often the liver, kidneys and muscles. The disease is called infectious jaundice.
Harmful bacteria of soil microflora
Billions of “bad” bacteria live in the soil. In a 30-centimeter thickness of 1 hectare of land there are up to 30 tons of bacteria. Possessing a powerful set of enzymes, they are engaged in the breakdown of proteins into amino acids, thereby taking an active part in the processes of decay. However, these bacteria bring a lot of trouble to humans. Thanks to the activity of these microbes, food spoils very quickly. Man learned to protect food long-term storage by sterilization, salting, smoking and freezing. Some types of these bacteria can spoil even salted and frozen foods. enter the soil from sick animals and humans. Some types of bacteria and fungi stay in the soil for decades. This is facilitated by the ability of these microorganisms to form spores, which protect them from unfavorable environmental conditions for many years. They cause the most dangerous diseases - anthrax, botulism, and tetanus.
Rice. 18. The causative agent of anthrax. It remains in the soil in a spore-like state for decades. Especially dangerous disease. Its second name is malignant carbuncle. The prognosis of the disease is unfavorable.
Rice. 19. The causative agent of botulism produces a powerful toxin. 1 microgram of this poison kills a person. Botulinum toxin affects nervous system, oculomotor nerves, up to paralysis and cranial nerves. The mortality rate from botulism reaches 60%.
Rice. 20. The causative agents of gas gangrene multiply very quickly in soft tissues the body without access to air, causing severe damage. In a spore-like state, it persists in the external environment for a long time.
Rice. 21. Putrefactive bacteria.
Rice. 22. Damage to food products by putrefactive bacteria.
Harmful bacteria that damage wood
A number of bacteria and fungi intensively decompose fiber, playing an important sanitary role. However, among them there are bacteria that cause serious diseases in animals. Molds destroy wood. Wood staining mushrooms paint wood in different colors. House mushroom leads the wood to a rotten state. As a result of the vital activity of this fungus, they are destroyed wooden buildings. The activity of these fungi causes great damage in the destruction of livestock buildings.
Rice. 23. The photo shows how the house fungus destroyed the wooden floor beams.
Rice. 24. Spoiled appearance logs (blue staining) affected by wood staining fungus.
Rice. 25. Brownie Merulius mushroom Lacrimans. a – cotton wool mycelium; b – young fruiting body; c – old fruiting body; d – old mycelium, cords and wood rot.
Harmful bacteria in food
Products contaminated with dangerous bacteria become a source of intestinal diseases: typhoid fever, salmonellosis, cholera, dysentery etc. Toxins that are released staphylococci and botulism bacilli, cause toxic infections. Cheeses and all dairy products may be affected butyric acid bacteria, which cause butyric acid fermentation, resulting in products appearing bad smell and color. Vinegar sticks cause acetic fermentation, which leads to sour wine and beer. Bacteria and micrococci that cause rotting contain proteolytic enzymes that break down proteins, which gives products a foul-smelling odor and bitter taste. Products become covered in mold as a result of damage to mold fungi.
Rice. 26. Bread affected by mold.
Rice. 27. Cheese affected by mold and putrefactive bacteria.
Rice. 28. “Wild yeast” Pichia pastoris. The photo was taken at 600x magnification. The worst pest of beer. Found everywhere in nature.
Harmful bacteria that decompose dietary fats
Butyric acid microbes are everywhere. 25 of their species cause butyric acid fermentation. Life activity fat-digesting bacteria leads to rancidity of the oil. Under their influence, soybean and sunflower seeds become rancid. Butyric acid fermentation, which is caused by these microbes, spoils the silage, and it is poorly eaten by livestock. And wet grain and hay, infected with butyric acid microbes, self-heats. The moisture contained in butter, is a good environment for breeding putrefactive bacteria and yeast fungi. Because of this, the oil deteriorates not only outside, but also inside. If the oil is stored for a long time, then it can settle on its surface. mold fungi.
Rice. 29. Caviar oil affected by fat-splitting bacteria.
Harmful bacteria affecting eggs and egg products
Bacteria and fungi penetrate into eggs through the pores of the outer shell and its damage. Most often, eggs are infected with salmonella bacteria and molds, egg powder - salmonella and .
Rice. 30. Spoiled eggs.
Harmful bacteria in canned food
for humans are toxins botulinum bacillus and perfringens bacillus. Their spores exhibit high heat resistance, which allows microbes to remain viable after pasteurization of canned food. Being inside the jar, without access to oxygen, they begin to multiply. This releases carbon dioxide and hydrogen, which causes the jar to swell. Eating such a product causes severe food toxicosis, which is characterized by an extremely severe course and often ends in the death of the patient. Canned meat and vegetables are amazing acetic acid bacteria, As a result, the contents of the canned food sour. Development does not cause bloating of canned food, since staphylococcus does not produce gases.
Rice. 31. Canned meat affected by acetic acid bacteria, as a result of which the contents of the cans turn sour.
Rice. 32. Swollen canned food may contain botulinum bacilli and perfringens bacilli. The jar is inflated by carbon dioxide, which is released by bacteria during reproduction.
Harmful bacteria in grain products and bread
Ergot and other molds that infect grains are the most dangerous for humans. The toxins of these mushrooms are heat stable and are not destroyed by baking. Toxicoses caused by the use of such products are severe. Torment, stricken lactic acid bacteria, has an unpleasant taste and specific smell, lumpy in appearance. Already baked bread is affected Bacillus subtilis(Bac. subtilis) or “gravid disease”. The bacilli secrete enzymes that break down bread starch, which is manifested, first, by an odor not characteristic of bread, and then by the stickiness and viscousness of the bread crumb. Green, white and capitate mold affects already baked bread. It spreads through the air.
Rice. 33. In the photo there is purple ergot. Low doses of ergot cause severe pain, mental disorders and aggressive behavior. High doses of ergot cause painful death. Its action is associated with muscle contraction under the influence of fungal alkaloids.
Rice. 34. Mold mycelium.
Rice. 35. Spores of green, white and capitate molds can fall from the air onto already baked bread and infect it.
Harmful bacteria that affect fruits, vegetables and berries
Fruits, vegetables and berries are seeded soil bacteria, mold fungi and yeast that causes intestinal infections. The mycotoxin patulin, which is secreted mushrooms of the genus Penicillium, can cause cancer in humans. Yersinia enterocolitica causes the disease yersiniosis or pseudotuberculosis, which affects the skin, gastrointestinal tract and other organs and systems.
Rice. 36. Damage to berries by mold fungi.
Rice. 37. Skin lesions due to yersiniosis.
Harmful bacteria enter the human body through food, air, wounds and mucous membranes. The severity of diseases caused by pathogenic microbes depends on the poisons they produce and the toxins produced by them. mass death. Over the course of thousands of years, they have acquired many adaptations that allow them to penetrate and remain in the tissues of a living organism and resist immunity.
To study the harmful effects of microorganisms on the body and develop preventive measures is the task of man!
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
Bacteria means “stick” in Greek. This name does not mean that harmful bacteria are meant.
They were given this name because of their shape. Most of these single cells look like rods. They also come in squares and star-shaped cells. For a billion years, bacteria do not change their appearance; they can only change internally. They can be movable or immobile. Bacteria On the outside it is covered with a thin shell. This allows it to maintain its shape. There is no nucleus or chlorophyll inside the cell. There are ribosomes, vacuoles, cytoplasmic outgrowths, and protoplasm. The largest bacterium was found in 1999. It was called the "Grey Pearl of Namibia". Bacteria and bacillus mean the same thing, they just have different origins.
Man and bacteria
In our body there is a constant battle between harmful and beneficial bacteria. Thanks to this process, a person receives protection from various infections. Various microorganisms surround us at every step. They live on clothes, fly in the air, they are omnipresent.
The presence of bacteria in the mouth, and this is about forty thousand microorganisms, protects the gums from bleeding, from periodontal disease and even from sore throat. If a woman’s microflora is disturbed, she may develop gynecological diseases. Compliance elementary rules personal hygiene will help avoid such failures.
Human immunity completely depends on the state of the microflora. Only in gastrointestinal tract contains almost 60% of all bacteria. The rest are located in the respiratory system and in the reproductive system. About two kilograms of bacteria live in a person.
The appearance of bacteria in the body
A newly born baby has a sterile intestine.
After his first breath, many microorganisms enter the body with which he was previously unfamiliar. When the baby is first put to the breast, the mother transfers beneficial bacteria with milk, which will help normalize the intestinal microflora. It is not for nothing that doctors insist that the mother immediately after the birth of her child breastfeed him. They also recommend extending this feeding as long as possible.
Beneficial bacteria
Beneficial bacteria are: lactic acid bacteria, bifidobacteria, E. coli, streptomycents, mycorrhizae, cyanobacteria.
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, 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
| 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 for a long time reside in the body and absorb beneficial substances from it. However, they can cause an infectious disease.
The most dangerous bacteria
One of the most resistant bacteria is methicillin. It is better known as Staphylococcus aureus (Staphylococcus aureus). can cause not one, but several infectious diseases. Some types of these bacteria are resistant to powerful antibiotics and antiseptics. Strains of this bacterium can live in the upper respiratory tract, open wounds and urinary tract of every third inhabitant of the Earth. For a person with strong immunity, 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, the body becomes intoxicated, there is a very strong fever, rashes on the body, and the liver and spleen become enlarged. 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 the death of a person is It causes tuberculosis, which is resistant to drugs. If you do not seek help in a timely manner, a person may die.
Measures to prevent the spread of infections
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 man can resist harmful bacteria, strengthening your 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.
