Bacteria - good, bad, eternal. Use of bacteria in industry

Article for the “bio/mol/text” competition: Are there medications that do not cause side effects and complications, are highly effective and safe? The closest to these ideal characteristics came probiotic preparations(from living microorganisms - human symbionts) and bacteriophages(bacterial viruses). When introduced into the human body, they enter into a struggle for existence with pathogens of infectious diseases or, in the case of bacteriophages, decompose them from the inside like a guerrilla. Probiotics and phages with different specificities affect pathogenic bacteria; all processes develop within the microbiocenosis of a certain area of ​​the human body and are aimed at preserving the habitat, in other words, maintaining homeostasis. Probiotics and phages are usually used separately, but their combined use may be promising.

Note!

The sponsor of the nomination “Best article on the mechanisms of aging and longevity” is the Science for Life Extension Foundation. The audience award was sponsored by Helicon.

Competition sponsors: Biotechnology Research Laboratory 3D Bioprinting Solutions and Scientific Graphics, Animation and Modeling Studio Visual Science.

Wedge is knocked out with wedge.

Folk wisdom

Biotechnology - medicine

In modern medical practice, a large number of drugs obtained through the vital activity of microorganisms are used. This includes vitamins, enzymes, genetically engineered hormones and interferons, blood substitutes and, of course, antibiotics. Actually, even medical alcohol - this universal antiseptic, folk analgesic and antidepressant - is a product of the fermentative metabolism of yeast fungi. Traditional and new, highly effective, natural and chemically modified drugs, different in structure and mechanism of action, in the creation of which microorganisms participated, are used to treat various diseases.

When the medicine is more dangerous than the disease

In the practice of using medicines, the doctor has to encounter so-called side effects, which can develop along with the main effect of the medicine and limit the possibilities of its use. Adverse reactions occur especially often in cases of use of drugs that have a multifaceted pharmacological effect (remember the same ethyl alcohol), while the goal of treatment is achieved through the use of only some aspects of the pharmacodynamics of a given drug.

Antibiotics deserve special attention in this sense, since they are the drugs of choice in the treatment of most infectious diseases, and the prescription of antibiotics is not always preceded by the necessary microbiological studies. There are frequent cases of irrational use of broad-spectrum antibiotics, patient violations of drug regimens, and even completely uncontrolled self-medication. And even when used correctly, the antibacterial effect of antibiotics extends not only to pathogenic, but also to the normal microbial flora of the body. Under the influence of antibiotics, bifidobacteria, lactobacilli, symbiotic strains of Escherichia coli and other beneficial microbes die. The vacated ecological niches are immediately populated by opportunistic bacteria and fungi (usually resistant to antibiotics), which were previously present on the skin and in non-sterile body cavities in small quantities - their reproduction was restrained by normal microflora. Antibiotic therapy, for example, can promote the transformation of peaceful saprophytic yeast-like fungi Candida albicans(Fig. 1), living on the mucous membranes of the oral cavity, trachea and intestines, into rapidly multiplying microorganisms that cause a number of local and general lesions.

Figure 1. Yeast-like fungi Candida albicans and the consequences of their active reproduction. A - Cells Candida albicans under an electron microscope. b - Manifestations of candidiasis. Drawings from the sites velvet.by and www.medical-enc.ru.

Other side effects may be based on individual characteristics of the body’s interaction with the antibiotic: intolerance to the drug may be of an allergic or pseudo-allergic nature, be a consequence of enzymopathies, or fall into the mysterious category of idiosyncrasies (until the mechanism of intolerance is clarified).

Probiotics instead of antibiotics?

Currently, medical science and health authorities around the world are faced with a responsible task - the creation of effective antibacterial drugs that cause the least pronounced adverse reactions.

One of the possible solutions to the problem is the development and widespread pharmacotherapeutic use of drugs based on living cultures of representatives of normal microflora ( probiotics) for the correction of human microbiocenoses and for the treatment of pathological conditions. The use of bacterial preparations is based on understanding the role of the normal microflora of the body in processes that provide nonspecific resistance to infections, in the formation of the immune response, as well as on establishing the antagonistic role of normal flora and its participation in the regulation of metabolic processes.

I.I. is considered the founder of the theory of probiotics. Mechnikov. He believed that maintaining human health and prolonging youth largely depended on lactic acid bacteria living in the intestines, which were capable of suppressing the processes of decay and the formation of toxic products. Back in 1903, Mechnikov proposed the practical use of microbial antagonist cultures to combat pathogenic bacteria.

According to some sources, the term “probiotics” was coined by Werner Kollath in 1953 and has been interpreted repeatedly and differently by both scientists and regulatory organizations. Kollat ​​called probiotics substances necessary for the development of a healthy organism, a kind of “promoters of life” - as opposed to antibiotics. Lilly and Stilwell, who are often credited with coining the term, also agreed with the end of this statement, but they clarified that probiotics are substances produced by some microorganisms and stimulating the growth of others. The vast majority of definitions revolved around the adoption of viable microbes in order to modulate the intestinal microflora. According to the consensus interpretation of the WHO and FAO expert council, Probiotics are live microorganisms that, when taken in sufficient quantities, provide health benefits. A significant contribution to the development of the modern concept of probiotics was made by the famous biochemist and animal nutrition specialist Marcel Vanbelle. T.P. Lyons and R.J. Fallon in 1992 called our time “the coming era of probiotics” (and they were right, judging by the incredible growth in their sales - Ed.) .

Compared to traditional antibacterial drugs, probiotics have a number of advantages: harmlessness (however, not for all diagnoses and not for all patients - Ed.), the absence of adverse reactions, allergenicity and negative effects on normal microflora. At the same time, the authors of a number of studies associate the use of these biological products with a pronounced clinical effect in the treatment (follow-up treatment) of acute intestinal infections. An important feature of probiotics, according to some data, is their ability to modulate immune reactions, in some cases have an antiallergic effect, and regulate digestion.

Currently, a number of similar bacterial preparations are widely used in medicine. Some of them contain bacteria that constantly live in the human body (“Lactobacterin”, “Bifidumbacterin”, “Colibacterin”, “Bifikol”), others consist of microorganisms that are not “residents” of the human body, but are capable of colonizing the mucous membranes for a certain time or wound surfaces, creating a protective biofilm on them (Fig. 2) and producing substances that are destructive to pathogenic bacteria. Such drugs include, in particular, “Biosporin” based on saprophytic bacteria Bacillus subtilis and “A-bacterin”, consisting of living cells of viridans aerococcus - Aerococcus viridans .

Beneficial microbe - aerococcus

Some aerococci (Fig. 3) are considered opportunistic microbes because they can cause diseases in animals (for example, gaffkemia in lobsters) and people with immunodeficiencies. Aerococci are often found in the air of hospital wards and on medical supplies, are isolated from patients with streptococcal and staphylococcal infections and also have a certain morphological similarity to these dangerous bacteria.

Figure 3. Cells and colonies of aerococci. A - Bacteria under a conventional light microscope. b - Bacteria under an electron microscope. Round cells arranged in pairs and tetrads are visible. V - Colonies of aerococci on a nutrient medium with the addition of blood. The green color around the colonies is the result of partial destruction of hemoglobin. Photo (a) from the site codeofconduc.com, (b) and (c) - taken by the authors of the article.

Figure 4. Suppression of the growth of pathogenic bacteria by aerococci. Zones of significant growth retardation were recorded during the cultivation of vibrios, staphylococci, diphtheria bacillus, and providence. Pseudomonas aeruginosa ( Pseudomonas aeruginosa) is resistant to the antagonistic action of aerococci. Photo of the authors of the article.

But the team of the Department of Microbiology of the Dnepropetrovsk Medical Academy managed to identify a strain among aerococci that is not only harmless to humans, but also exhibits pronounced antagonistic activity against a wide range of pathogens of infectious diseases. Thus, a drug was developed and introduced that has no analogues in world practice - the probiotic “A-bacterin” for external and oral use, which is not inferior in its effect on the human microflora to expensive antibiotic drugs (Fig. 4).

The antagonistic properties of aerococci are associated with the production of hydrogen peroxide (a substance widely used in medicine as an antiseptic) - a stable feature of the production strain A. viridans, from which “A-bacterin” is prepared. Another bactericidal substance, a product of the metabolism of aerococci, is the superoxide radical (Fig. 5), formed by these bacteria during the oxidation of lactic acid. Moreover, the ability of aerococci to oxidize lactic acid is very important when using the drug in dentistry, since one of the causes of caries is lactic acid formed by streptococci.

Figure 5. Bactericidal substances produced by aerococci: hydrogen peroxide (A) and superoxide radical (b) . Drawing from the site tofeelwell.ru.

A low-molecular acid-resistant and heat-stable peptide was identified in the culture fluid of aerococci viridocin, which has a wide range of antagonistic activity against those microorganisms that most often cause hospital infections and are involved in the formation of physiological and pathological microbiocenosis of the human intestine. Besides, A. viridans produces a peptide into the external environment aerocin*, capable of killing yeast-like fungi. The use of “A-bacterin” with potassium iodide and ethonium is effective for urogenital candidiasis, as it provides targeted damage to candida membranes. The same effect is achieved when the drug is used as a means of preventing candidiasis, which occurs, for example, due to immunosuppression during HIV infection.

* - Along with the production of hydrogen peroxide (due to NAD-independent lactate dehydrogenase), and in the presence of potassium iodide and the formation of hypoiodide (due to glutathione peroxidase) with a more pronounced bactericidal effect than hydrogen peroxide, aerococci also have non-oxide components of antagonistic activity. They form a low molecular weight thermostable peptide aerocin, which belongs to the class of microcins, active against Proteus, staphylococci, Escherichia and Salmonella. Aerocin was isolated from the culture liquid by salting out methods, electrodialysis and paper chromatography, after which its amino acid composition was established and therapeutic effectiveness was shown against experimental salmonella infection in mice. Aerococci are also characterized by adhesion to epithelial and some other cells, that is, resistance to pathogenic bacteria occurs, including at the level of biofilms and colonization resistance.

In addition to the ability to suppress the proliferation of pathogenic bacteria, “A-bacterin” promotes the regeneration of damaged tissue, exhibits an adjuvant effect, stimulates phagocytosis and can be recommended for patients sensitized to antibiotics and chemotherapeutic agents. Today, “A-bacterin” is successfully used for the treatment of burns and surgical wounds, for the prevention and treatment of diarrhea, as well as in dental, urological and gynecological practice. Orally, “A-bacterin” is used to correct intestinal microflora, prevent and treat intestinal infections, correct certain biochemical parameters (cholesterol profile and lactic acid level) and activate the immune system. Other probiotics are also widely used for the treatment and prevention of intestinal infections, especially in infants who are bottle-fed. Food products containing live probiotic cultures are also popular.

Healing viruses

When treating infections, it is important to create a high concentration of the antimicrobial drug precisely at the site of localization of the pathogen. Using antibiotics in the form of tablets or injections, this is quite difficult to achieve. But in the case of phage therapy, it is enough if at least single bacteriophages reach the infectious focus. Having detected pathogenic bacteria and penetrated them, phages begin to multiply very quickly. With each reproduction cycle, which lasts about half an hour, the number of phages increases tens or even hundreds of times. After the destruction of all cells of the pathogen, phages are no longer able to reproduce and, due to their small size, are freely excreted from the body along with other decay products.

Probiotics and phages together

Bacteriophages have proven themselves in the prevention and treatment of intestinal infections and purulent-inflammatory processes. The causative agents of these diseases often become resistant to antibiotics, but remain sensitive to phages. Recently, scientists have become interested in the prospect of using bacteriophages and probiotics together. It is assumed that when such a complex drug is prescribed, the phage first destroys pathogenic bacteria, and then the vacated ecological niche is populated by beneficial microorganisms, forming a stable microbiocenosis with high protective properties. This approach has already been tested on farm animals. It will probably also enter medical practice.

A closer interaction in the “bacteriophage + probiotic” system is also possible. It is known that bacteria - representatives of normal human microflora - are capable of adsorbing various viruses on their surface, preventing them from penetrating human cells. It turned out that bacteriophages can also be adsorbed in the same way: they are not able to penetrate the cell of a bacterium that is resistant to them, but use it as a “vehicle” to move around in the human body. This phenomenon is called bacteriophage translocation.

The internal environment of the body, its tissues and blood are considered sterile. In fact, through microscopic damage to the mucous membranes, symbiont bacteria periodically penetrate into the bloodstream (Fig. 7), although they are quickly destroyed there by cells of the immune system and bactericidal substances. In the presence of an infectious focus, the barrier properties of surrounding tissues are often impaired, and their permeability increases. This increases the likelihood that circulating probiotic bacteria will penetrate there along with phages attached to them. In particular, in people with urinary tract infections taking A-bacterin orally, aerococci were found in the urine, and their number was consistently low, which indicated precisely transfer aerococci, and not about their reproduction in these organs. Aerococci and the most common causative agents of urological infections belong to completely different groups of bacteria, and therefore are sensitive to different bacteriophages. This opens up interesting prospects for creating a complex drug, for example, based on A. viridans and phages that infect intestinal bacteria. Such developments are being carried out at the Department of Microbiology of the Dnepropetrovsk Medical Academy, but they have not yet reached the stage of laboratory research.

The article was written with the participation of Yurgel L.G. and Kremenchutsky G.N.

From the editor

The editors of "Biomolecules" draw the attention of readers to the fact that the authors of articles in the "Own Work" nomination share important and interesting details their research, lead own view on the situation in your industry. The Biomolecules team does not believe that the issue of the advisability of using probiotics has already been resolved.

The results of research on such substances, no matter how amazing they are, must be confirmed accordingly: the drug must undergo the necessary phases of clinical trials for the medical community to recognize it as safe and effective medicine, and only after that recommend to patients. Naturally, we are talking about tests according to international standards, and not as it sometimes happens with us - on 12 patients of a rural infirmary who stated that it just-terribly-helped them. A good guideline for doctors and patients would be the approval of some probiotic drugs, for example, by the American FDA, but alas...

In the meantime, probiotics taken orally should not be viewed as drugs, but as nutritional supplements. Moreover, the properties of the drug declared by the manufacturer cannot be transferred to other probiotics: they are critical strain(not a genus or even a species) and number of colony forming units. You also need to keep in mind that such products are influenced by many factors related to production, storage conditions and periods, consumption and digestion.

The largest nutrition and treatment organizations in the world consider: There is not yet enough evidence to suggest that probiotics have a positive effect on health(especially all of them, regardless of the initial state of this same health). And it’s not that controllers are convinced of the ineffectiveness of these drugs - it’s just that, as a rule, in the medical studies conducted, they do not see a reliable cause-and-effect relationship between taking probiotics and positive changes. It is also worth remembering those studies where some probiotic turned out to be ineffective or even had a negative effect.

One way or another, the probiotic trend has potential - at least in the prevention and treatment of various enteritis (if we are talking about oral administration). It's just not that simple. Not as simple as the manufacturer, doctor and patient would like. Probably, the probiotics on the shelves of our stores and pharmacies were simply “born a little premature.” So we are waiting for killer evidence from development scientists and manufacturers. And we wish the authors of the article success in this difficult field and, of course, in the search for new interesting properties of microorganisms.

Literature

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Microorganisms are widely used in the food industry, households, and the microbiological industry to produce amino acids, enzymes, organic acids, vitamins, etc. Classic microbiological production includes winemaking, brewing, making bread, lactic acid products and food vinegar. For example, winemaking, brewing and the production of yeast dough are impossible without the use of yeast, which is widespread in nature.

The history of industrial production of yeast began in Holland, where the first factory producing yeast was founded in 1870. The main type of product was compressed yeast with a moisture content of about 70%, which could be stored for only a few weeks. Long-term storage was impossible, since the pressed yeast cells remained alive and retained their activity, which led to their autolysis and death. One of the methods for industrially preserving yeast is drying. In dry yeast, at low humidity, the yeast cell is in an anabiotic state and can persist for a long time. The first dry yeast appeared in 1945. In 1972, the second generation of dry yeast, the so-called instant yeast, appeared. Since the mid-1990s, a third generation of dry yeast has emerged: baker's yeast Saccharomyces cerevisiae, which combine the benefits of instant yeast with a highly concentrated complex of specialized baking enzymes in one product. This yeast not only improves the quality of bread, but also actively resists the process of staling.

Baker's yeast Saccharomyces cerevisiae are also used in the production of ethyl alcohol.

Winemaking uses many different races of yeast to produce a unique brand of wine with unique qualities.

Lactic acid bacteria are involved in the preparation of foods such as sauerkraut, pickles, pickled olives and many other pickled foods.

Lactic acid bacteria convert sugar into lactic acid, which protects food products from putrefactive bacteria.

With the help of lactic acid bacteria, a wide range of lactic acid products, cottage cheese, and cheese are prepared.

However, many microorganisms play a negative role in human life, being pathogens of diseases in humans, animals and plants; they can cause food spoilage, destruction of various materials, etc.

To combat such microorganisms, antibiotics were discovered - penicillin, streptomycin, gramicidin, etc., which are metabolic products of fungi, bacteria and actinomycetes.

Microorganisms provide humans with the necessary enzymes. Thus, amylase is used in the food, textile, and paper industries. Protease causes the breakdown of proteins in various materials. In the East, protease from mushrooms was used several centuries ago to make soy sauce. Currently, it is used in the production of detergents. When canning fruit juices, an enzyme such as pectinase is used.

Microorganisms are used for wastewater treatment and food processing waste. The anaerobic decomposition of organic matter in waste produces biogas.

In recent years, new production facilities have appeared. Carotenoids and steroids are obtained from mushrooms.

Bacteria synthesize many amino acids, nucleotides and other reagents for biochemical research.

Microbiology is a rapidly developing science, the achievements of which are largely related to the development of physics, chemistry, biochemistry, molecular biology, etc.

To successfully study microbiology, knowledge of the listed sciences is required.

This course focuses primarily on food microbiology. Many microorganisms live on the surface of the body, in the intestines of humans and animals, on plants, on food products and on all objects around us. Microorganisms consume a wide variety of foods and adapt extremely easily to changing living conditions: heat, cold, lack of moisture, etc. They multiply very quickly. Without knowledge of microbiology, it is impossible to competently and effectively manage biotechnological processes, maintain high quality food products at all stages of its production and prevent the consumption of products containing pathogens of foodborne illnesses and poisoning.

It should be especially emphasized that microbiological studies of food products, not only from the point of view of technological features, but also, no less important, from the point of view of their sanitary and microbiological safety, are the most complex object of sanitary microbiology. This is explained not only by the diversity and abundance of microflora in food products, but also by the use of microorganisms in the production of many of them.

In this regard, in microbiological analysis of food quality and safety, two groups of microorganisms should be distinguished:

– specific microflora;

– nonspecific microflora.

Specific– these are cultural races of microorganisms that are used to prepare a particular product and are an essential link in the technology of its production.

This microflora is used in the technology of producing wine, beer, bread, and all fermented milk products.

Nonspecific are microorganisms that enter food products from the environment, contaminating them. Among this group of microorganisms, saprophytic, pathogenic and opportunistic microorganisms are distinguished, as well as microorganisms that cause food spoilage.

The degree of contamination depends on many factors, which include the correct procurement of raw materials, their storage and processing, compliance with technological and sanitary regimes for the production of products, their storage and transportation.

Introduction

Modern biotechnology is based on the achievements of natural science, engineering, technology, biochemistry, microbiology, molecular biology, and genetics. Biological methods are used to combat environmental pollution and pests of plant and animal organisms. The achievements of biotechnology also include the use of immobilized enzymes, the production of synthetic vaccines, and the use of cell technology in breeding.

Bacteria, fungi, algae, lichens, viruses, and protozoa play a significant role in human life. Since ancient times, people have used them in the processes of baking bread, making wine and beer, and in various industries.

Microorganisms help humans in the production of effective protein nutrients and biogas. They are used when applying biotechnical methods of air and wastewater purification, when using biological methods for exterminating agricultural pests, when obtaining medicinal drugs, and when destroying waste materials.

The main goal of this work is to study methods and conditions for cultivating microorganisms

· Familiarize yourself with the areas of application of microorganisms

· Study the morphology and physiology of microorganisms

· Study the main types and composition of nutrient media

· Give the concept and become familiar with the bioreactor

· Reveal the basic methods of cultivating microorganisms

Morphology and physiology of microorganisms

Morphology

Classification of microorganisms

Bacteria

Bacteria are single-celled prokaryotic microorganisms. Their size is measured in micrometers (µm). There are three main forms: spherical bacteria - cocci, rod-shaped and convoluted.

Cocci(Greek kokkos - grain) have a spherical or slightly elongated shape. They differ from each other depending on how they are located after division. Cocci located singly are micrococci, and cocci located in pairs are diplococci. Streptococci divide in one plane and after division do not diverge, forming chains (Greek streptos - chain). Tetracocci form combinations of four cocci as a result of division in two mutually perpendicular planes, sarcina (lat. sarcio - to bind) are formed by division in three mutually perpendicular planes and look like clusters of 8-16 cocci. As a result of random division, staphylococci form clusters resembling a bunch of grapes (Greek staphyle - bunch of grapes).

Rod-shaped bacteria (Greek bacteria - stick) capable of forming spores are called bacilli if the spore is not wider than the stick itself, and clostridia if the diameter of the spore exceeds the diameter of the stick. Rod-shaped bacteria, unlike cocci, are diverse in size, shape and arrangement of cells: short (1-5 µm), thick, with rounded ends, bacteria of the intestinal group; thin, slightly curved tuberculosis bacilli; thin diphtheria rods located at an angle; large (3-8 microns) anthrax bacilli with “chopped off” ends, forming long chains - streptobacilli.

TO crimped forms of bacteria include vibrios, which have a slightly curved comma-shaped shape (Vibrio cholera) and spirilla, consisting of several curls. Convoluted forms also include Campylobacter, which under a microscope looks like the wings of a flying seagull.

Structure of a bacterial cell.

The structural elements of a bacterial cell can be divided into:

a) permanent structural elements - are present in each type of bacteria throughout the life of the bacterium; this is the cell wall, cytoplasmic membrane, cytoplasm, nucleoid;

B) unstable structural elements that not all types of bacteria are capable of forming, and those bacteria that form them can lose them and acquire them again depending on the conditions of existence. These are the capsule, inclusions, pili, spores, flagella.

Rice. 1.1. Bacterial cell structure

Cell wall covers the entire surface of the cell. Gram-positive bacteria have a thicker cell wall: up to 90% is a polymer compound of peptidoglycan associated with teichoic acids and a layer of protein. In gram-negative bacteria, the cell wall is thinner, but more complex in composition: it consists of a thin layer of peptidoglycan, lipopolysaccharides, and proteins; it is covered with an outer membrane.

Functions of the cell wallare that it:

Is an osmotic barrier

Determines the shape of the bacterial cell,

Protects the cell from environmental influences,

Carries a variety of receptors that facilitate the attachment of phages, colicins, as well as various chemical compounds,

Through the cell wall, nutrients enter the cell and metabolic products are released,

The O-antigen is localized in the cell wall and endotoxin (lipid A) of bacteria is associated with it.

Cytoplasmic membrane

Adjacent to the bacterial cell wall cytoplasmic membrane , the structure of which is similar to the membranes of eukaryotes ( consists of a lipid bilayer, mainly phospholipids with built-in surface and integral proteins). She provides:

Selective permeability and transport of soluble substances into the cell,

Electron transport and oxidative phosphorylation,

Isolation of hydrolytic exoenzymes, biosynthesis of various polymers.

The cytoplasmic membrane limits bacterial cytoplasm , which represents granular structure. Localized in the cytoplasm ribosomes and bacterial nucleoid, it may also contain inclusions and plasmids(extrachromosomal DNA). In addition to the obligatory structures, bacterial cells can have spores.

Cytoplasm- The internal gel-like contents of the bacterial cell are permeated with membrane structures that create a rigid system. The cytoplasm contains ribosomes (in which protein biosynthesis is carried out), enzymes, amino acids, proteins, and ribonucleic acids.

Nucleoid- This is a bacterial chromosome, a double strand of DNA, closed in a ring, associated with the mesosome. Unlike the nucleus of eukaryotes, the DNA strand is freely located in the cytoplasm and does not have a nuclear membrane, nucleolus, or histone proteins. The DNA strand is many times longer than the bacterium itself (for example, E. coli has a chromosome length of more than 1 mm).

In addition to the nucleoid, the cytoplasm may contain extrachromosomal heredity factors called plasmids. These are short, circular strands of DNA attached to mesosomes.

Inclusions are contained in the cytoplasm of some bacteria in the form of grains that can be detected by microscopy. Mostly this is a supply of nutrients.

Drank(Latin pili - hairs) otherwise cilia, fimbriae, fimbriae, villi - short thread-like processes on the surface of bacteria.

Flagella. Many types of bacteria are able to move thanks to the presence of flagella. Of the pathogenic bacteria, only among the rods and convoluted forms there are mobile species. Flagella are thin elastic threads, the length of which in some species is several times greater than the length of the body of the bacterium itself.

The number and location of flagella is a characteristic species characteristic of bacteria. Bacteria are distinguished: monotrichs - with one flagellum at the end of the body, lophotrichs - with a bundle of flagella at the end, amphitrichs, which have flagella at both ends, and peritrichs, in which the flagella are located over the entire surface of the body. Monotrichs include Vibrio cholerae, peritrichs include Salmonella typhoid.

Capsule- the outer mucous layer that many bacteria have. In some species it is so thin that it can only be detected in an electron microscope - this is a microcapsule. In other types of bacteria, the capsule is well defined and visible in a conventional optical microscope - this is a macrocapsule.

Mycoplasmas

Mycoplasmas are prokaryotes, their sizes are 125-200 nm. These are the smallest of cellular microbes, their size is close to the resolution limit of an optical microscope. They lack a cell wall. The absence of a cell wall is associated with the characteristic features of mycoplasmas. They do not have a constant shape, so spherical, oval, and thread-like shapes are found.

Rickettsia

Chlamydia

Actinomycetes

Actinomycetes are unicellular microorganisms that belong to prokaryotes. Their cells have the same structure as bacteria: a cell wall containing peptidoglycan, a cytoplasmic membrane; the cytoplasm contains the nucleoid, ribosomes, mesosomes, and intracellular inclusions. Therefore, pathogenic actinomycetes are sensitive to antibacterial drugs. At the same time, they have a form of branching intertwining threads similar to mushrooms, and some actinomycetes belonging to the Strentomycetes family reproduce by spores. Other families of actinomycetes reproduce by fragmentation, that is, the disintegration of filaments into separate fragments.

Actinomycetes are widespread in the environment, especially in soil, and participate in the cycle of substances in nature. Among actinomycetes there are producers of antibiotics, vitamins, and hormones. Most antibiotics currently used are produced by actinomycetes. These are streptomycin, tetracycline and others.

Spirochetes.

Spirochetes are prokaryotes. They have characteristics common to both bacteria and protozoan microorganisms. These are single-celled microbes, shaped like long, thin, spirally curved cells, capable of active movement. Under unfavorable conditions, some of them can turn into cysts.

Electron microscope studies made it possible to establish the structure of spirochete cells. These are cytoplasmic cylinders surrounded by a cytoplasmic membrane and a cell wall containing peptidoglycan. The cytoplasm contains the nucleoid, ribosomes, mesosomes, and inclusions.

Under the cytoplasmic membrane there are fibrils that provide various movements of spirochetes - translational, rotational, flexion.

Pathogenic representatives of spirochetes: Treponema pallidum - causes syphilis, Borrelia recurrentis - relapsing fever, Borrelia burgdorferi - Lyme disease, Leptospira interrogans - leptospirosis.

Mushrooms

Fungi (Fungi, Mycetes) are eukaryotes, lower plants, lacking chlorophyll, and therefore they do not synthesize organic carbon compounds, that is, they are heterotrophs, have a differentiated nucleus, and are covered with a shell containing chitin. Unlike bacteria, fungi do not have peptidoglycan in their shell, therefore they are insensitive to penicillins. The cytoplasm of fungi is characterized by the presence of a large number of various inclusions and vacuoles.

Among microscopic fungi (micromycetes) there are unicellular and multicellular microorganisms that differ in morphology and methods of reproduction. Fungi are characterized by a variety of methods of reproduction: division, fragmentation, budding, formation of spores - asexual and sexual.

In microbiological studies, one most often encounters molds, yeasts and representatives of the group of so-called imperfect fungi.

Mold form a typical mycelium spreading along the nutrient substrate. Aerial branches rise upward from the mycelium, ending in fruiting bodies of various shapes carrying spores.

Mucor or capitate molds (Mucor) are unicellular fungi with a spherical fruiting body filled with endospores.

Molds of the genus Aspergillus are multicellular fungi with a fruiting body that, under microscopy, resembles the tip of a watering can spraying streams of water; hence the name "watering mold". Some Aspergillus species are used industrially to produce citric acid and other substances. There are species that cause diseases of the skin and lungs in humans - aspergillosis.

Molds of the genus Penicillum, or racemes, are multicellular fungi with a fruiting body in the form of a brush. The first antibiotic, penicillin, was obtained from certain types of green mold. Among the penicilliums there are species pathogenic for humans that cause penicilliosis.

Various types of molds can cause spoilage of food products, medicines, and biological products.

Yeast - yeast fungi (Saccharomycetes, Blastomycetes) have the shape of round or oval cells, many times larger than bacteria. The average size of yeast cells is approximately equal to the diameter of a red blood cell (7-10 microns).

Viruses

Viruses- (lat. virus poison) - the smallest microorganisms that do not have a cellular structure, a protein synthesizing system and are capable of reproduction only in the cells of highly organized life forms. They are widespread in nature, affecting animals, plants and other microorganisms.

The mature viral particle, known as a virion, consists of nucleic acid - genetic material (DNA or RNA) that carries information about several types of proteins necessary for the formation of a new virus - covered with a protective protein shell - the capsid. The capsid is made up of identical protein subunits called capsomeres. Viruses may also have a lipid envelope over a capsid ( supercapsid), formed from the host cell membrane. The capsid consists of proteins encoded by the viral genome, and its shape underlies the classification of viruses based on morphological characteristics. Complex viruses also encode special proteins that help in capsid assembly. Complexes of proteins and nucleic acids are known as nucleoproteins, and the complex of viral capsid proteins with viral nucleic acid is called nucleocapsid.

Rice. 1.4. Schematic structure of the virus: 1 - core (single-stranded RNA); 2 - protein shell (Capsid); 3 - additional lipoprotein membrane; 4 - Capsomeres (structural parts of the Capsid).

Physiology of microorganisms

The physiology of microorganisms studies the vital activity of microbial cells, the processes of their nutrition, respiration, growth, reproduction, and patterns of interaction with the environment.

Metabolism

Metabolism– a set of biochemical processes aimed at obtaining energy and reproducing cellular material.

Features of metabolism in bacteria:

1) variety of substrates used;

2) intensity of metabolic processes;

4) the predominance of decay processes over synthesis processes;

5) the presence of exo- and endoenzymes of metabolism.

Metabolism consists of two interrelated processes: catabolism and anabolism.

Catabolism(energy metabolism) is the process of breaking down large molecules into simpler ones, as a result of which energy is released, which accumulates in the form of ATP:

a) breathing;

b) fermentation.

Anabolism(constructive metabolism) – ensures the synthesis of macromolecules from which the cell is built:

a) anabolism (with energy expenditure);

b) catabolism (with the release of energy);

In this case, the energy obtained in the process of catabolism is used. Bacterial metabolism is characterized by a high rate of process and rapid adaptation to changing environmental conditions.

In a microbial cell, enzymes are biological catalysts. By structure they are distinguished:

1) simple enzymes (proteins);

2) complex; consist of protein (active center) and non-protein parts; necessary for enzyme activation.

According to the place of action they distinguish:

1) exoenzymes (act outside the cell; take part in the breakdown of large molecules that cannot penetrate inside the bacterial cell; characteristic of gram-positive bacteria);

2) endoenzymes (act in the cell itself, ensuring the synthesis and breakdown of various substances).

Depending on the chemical reactions they catalyze, all enzymes are divided into six classes:

1) oxidoreductases (catalyze redox reactions between two substrates);

2) transferases (carry out intermolecular transfer of chemical groups);

3) hydrolases (carry out hydrolytic cleavage of intramolecular bonds);

4) lyases (attach chemical groups to two bonds, and also carry out reverse reactions);

5) isomerases (carry out isomerization processes, provide internal conversion with the formation of various isomers);

6) ligases, or synthetases (they connect two molecules, resulting in the cleavage of pyrophosphate bonds in the ATP molecule).

Nutrition

Nutrition refers to the processes of entry and exit of nutrients into and out of cells. Nutrition primarily ensures cell reproduction and metabolism.

Various organic and inorganic substances enter the bacterial cell during nutrition. Bacteria do not have special nutritional organs. Substances penetrate the entire surface of the cell in the form of small molecules. This way of eating is called holophytic. A necessary condition for the passage of nutrients into the cell is their solubility in water and small value (i.e. proteins must be hydrolyzed to amino acids, carbohydrates to di- or monosaccharides, etc.).

The main regulator of the entry of substances into the bacterial cell is the cytoplasmic membrane. There are four main mechanisms of substance entry:

-passive diffusion- along a concentration gradient, energy-intensive, without substrate specificity;

- facilitated diffusion- along a concentration gradient, substrate-specific, energy-intensive, carried out with the participation of specialized proteins permease;

- active transport against a concentration gradient, substrate-specific (special binding proteins in complex with permeases), energy-consuming (due to ATP), substances enter the cell in a chemically unchanged form;

- translocation (group transfer) - against a concentration gradient, using the phosphotransferase system, energy-consuming, substances (mainly sugars) enter the cell in forphorylated form.

Basic chemical elements - organogens necessary for the synthesis of organic compounds - carbon, nitrogen, hydrogen, oxygen.

Types of food. A variety of diets contribute to the widespread spread of bacteria. Microbes need carbon, oxygen, nitrogen, hydrogen, sulfur, phosphorus and other elements (organogens).

Depending on the source of carbon, bacteria are divided into:

1) autotrophs (use inorganic substances - CO2);

2) heterotrophs;

3) metatrophs (use organic substances of inanimate nature);

4) paratrophs (use organic substances of living nature).

Nutrition processes must provide the energy needs of the bacterial cell.

Based on energy sources, microorganisms are divided into:

1) phototrophs (able to use solar energy);

2) chemotrophs (obtain energy through redox reactions);

3) chemolithotrophs (use inorganic compounds);

4) chemoorganotrophs (use organic substances).

Among the bacteria are:

1) prototrophs (able to synthesize the necessary substances themselves from low-organized substances);

2) auxotrophs (they are mutants of prototrophs that have lost genes; they are responsible for the synthesis of certain substances - vitamins, amino acids, and therefore require these substances in finished form).

Microorganisms assimilate nutrients in the form of small molecules, so proteins, polysaccharides and other biopolymers can serve as sources of nutrition only after they are broken down by exoenzymes into simpler compounds.

Respiration of microorganisms.

Microorganisms obtain energy through respiration. Respiration is the biological process of transferring electrons through the respiratory chain from donors to acceptors with the formation of ATP. Depending on what is the final electron acceptor, there are aerobic and anaerobic respiration. In aerobic respiration, the final electron acceptor is molecular oxygen (O 2), in anaerobic respiration, bound oxygen (-NO 3, =SO 4, =SO 3).

Aerobic respiration hydrogen donor H 2 O

Anaerobic respiration

Nitrate oxidation of NO 3

(facultative anaerobes) hydrogen donor N 2

Sulfate oxidation of SO 4

(obligate anaerobes) hydrogen donor H 2 S

Based on the type of respiration, four groups of microorganisms are distinguished.

1.Obligate(strict) aerobes. They need molecular (atmospheric) oxygen to breathe.

2.Microaerophiles require a reduced concentration (low partial pressure) of free oxygen. To create these conditions, CO 2 is usually added to the gas mixture for cultivation, for example up to a 10 percent concentration.

3.Facultative anaerobes can consume glucose and reproduce under aerobic and anaerobic conditions. Among them there are microorganisms that are tolerant to relatively high (close to atmospheric) concentrations of molecular oxygen - i.e. aerotolerant,

as well as microorganisms that are capable, under certain conditions, of switching from anaerobic to aerobic respiration.

4.Strict anaerobes reproduce only under anaerobic conditions i.e. at very low concentrations of molecular oxygen, which in high concentrations is destructive for them. Biochemically, anaerobic respiration proceeds according to the type of fermentation processes; molecular oxygen is not used.

Aerobic respiration is energetically more efficient (more ATP is synthesized).

In the process of aerobic respiration, toxic oxidation products are formed (H 2 O 2 - hydrogen peroxide, -O 2 - free oxygen radicals), from which specific enzymes protect, primarily catalase, peroxidase, peroxide dismutase. Anaerobes lack these enzymes, as do redox potential regulation system (rH 2).

Growth and reproduction of bacteria

Bacterial growth is an increase in bacterial cell size without increasing the number of individuals in the population.

Reproduction of bacteria is a process that ensures an increase in the number of individuals in a population. Bacteria are characterized by a high reproduction rate.

Growth always precedes reproduction. Bacteria reproduce by transverse binary fission, in which two identical daughter cells are formed from one mother cell.

The process of bacterial cell division begins with the replication of chromosomal DNA. At the point of attachment of the chromosome to the cytoplasmic membrane (replicator point), an initiator protein acts, which causes the chromosome ring to break, and then despiralization of its threads occurs. The threads unwind, and the second thread attaches to the cytoplasmic membrane at the pro-replicator point, which is diametrically opposite to the replicator point. Due to DNA polymerases, an exact copy of each strand is completed along the matrix. Doubling of genetic material is a signal for doubling the number of organelles. In the septal mesosomes, a septum is being built that divides the cell in half. Double-stranded DNA is helicalized, twisted into a ring at the point of attachment to the cytoplasmic membrane. This is a signal for the cells to disperse along the septum. Two daughter individuals are formed.

The reproduction of bacteria is determined by the generation time. This is the period during which cell division occurs. The duration of generation depends on the type of bacteria, age, composition of the nutrient medium, temperature, etc.

Culture media

For the cultivation of bacteria, nutrient media are used, which have a number of requirements.

1. Nutritional value. The bacteria must contain all the necessary nutrients.

2. Isotonicity. Bacteria must contain a set of salts to maintain osmotic pressure, a certain concentration of sodium chloride.

3. Optimal pH (acidity) of the environment. The acidity of the environment ensures the functioning of bacterial enzymes; for most bacteria it is 7.2–7.6.

4. Optimal electronic potential, indicating the content of dissolved oxygen in the medium. It should be high for aerobes and low for anaerobes.

5. Transparency (growth of bacteria has been observed, especially for liquid media).

6. Sterility (absence of other bacteria).

Classification of culture media

1. By origin:

1) natural (milk, gelatin, potatoes, etc.);

2) artificial - media prepared from specially prepared natural components (peptone, aminopeptide, yeast extract, etc.);

3) synthetic - media of known composition, prepared from chemically pure inorganic and organic compounds (salts, amino acids, carbohydrates, etc.).

2. By composition:

1) simple - meat-extract agar, meat-extract broth, Hottinger agar, etc.;

2) complex - these are simple with the addition of an additional nutritional component (blood, chocolate agar): sugar broth,

bile broth, whey agar, yolk-salt agar, Kitt-Tarozzi medium, Wilson-Blair medium, etc.

3. By consistency:

1) solid (contain 3–5% agar-agar);

2) semi-liquid (0.15-0.7% agar-agar);

3) liquid (do not contain agar-agar).

Agar- polysaccharide of complex composition from seaweed, the main hardener for dense (solid) media.

4. Depending on the purpose of the PS, they are distinguished:

Differential diagnostic

Elective

Selective

Inhibitory

Media for maintaining culture

Cumulative (saturation, enrichment)

Preservative

Tests.

Differential diagnostic media are complex media on which microorganisms of different species grow differently, depending on the biochemical properties of the culture. They are designed to identify the species of microorganisms and are widely used in clinical bacteriology and genetic research.

Selective, inhibitory and elective PSs are designed for growing a strictly defined type of microorganism. These media serve to isolate bacteria from mixed populations and differentiate them from similar species. Various substances are added to their composition that suppress the growth of some species and do not affect the growth of others.

The medium can be made selective due to the pH value. Recently, antimicrobial agents such as antibiotics and other chemotherapeutic substances have been used as substances that impart a selective character to the media.

Selective PSs have found wide application in the isolation of pathogens of intestinal infections. When adding malachite or brilliant green, bile salts (in particular sodium taurocholic acid), significant amounts of sodium chloride or citrate salts, the growth of Escherichia coli is suppressed, but the growth of pathogenic coliform bacteria is not impaired. Some election media are prepared with the addition of antibiotics.

The media for maintaining the culture are designed so that they do not contain selective substances that can cause crop variability.

Cumulative PS (enrichment, saturation) are media in which certain types of crops or groups of crops grow faster and more intensively than accompanying ones. When cultivating on these media, inhibitory substances are usually not used, but, on the contrary, favorable conditions are created for the specific species present in the mixture. The basis of accumulation media are bile and its salts, sodium tetrathionate, various dyes, selenite salts, antibiotics, etc.

Preservative media are used for initial seeding and transportation of the test material.

There are also control PSs, which are used to monitor the sterility and general bacterial contamination of antibiotics.

5. Based on the set of nutrients, the following are distinguished:

Minimal media, which contain only sufficient food sources for growth;

Rich media containing many additional substances.

6. Based on the scale of use, PSs are divided into:

> production (technological);

> environments for scientific research with limited scope.

Industrial PS must be accessible, economical, convenient to prepare and use for large-scale cultivation. Media for scientific research, as a rule, are synthetic and rich in nutrients.

Selection of raw materials for constructing nutrient media

The quality of PS is largely determined by the completeness of the composition of nutrient substrates and the raw materials used for their preparation. The wide variety of types of raw material sources poses the difficult task of selecting the most promising ones suitable for constructing PS of the required quality. The decisive role in this issue is played, first of all, by the biochemical indicators of the composition of the raw material, on which the choice of the method and modes of its processing depends in order to make the most complete and effective use of the nutrients it contains.

To obtain PS with especially valuable properties, traditional sources of protein of animal origin are used, namely meat cattle (cattle), casein, fish and its products. The most fully developed and widely used PSs are those based on cattle meat.

Considering the shortage of Caspian sprat, which was widely used in the recent past, cheaper and more accessible non-food products of the fishing industry began to be used to obtain fish nutritional bases - dry krill, krill meat processing waste, filleted pollock and its overripe caviar. The most widespread is fish feed meal (FFM), which meets the requirements of biological value, availability and relative standard.

PS based on casein, which contains all the components found in milk: fat, lactose, vitamins, enzymes and salts, are quite widespread. However, it should be noted that due to the rise in prices of milk processing products, as well as an increase in demand for casein on the world market, its use is somewhat limited.

From non-food sources of protein of animal origin, as a raw material for the construction of complete PS, it is necessary to isolate the blood of slaughtered animals, which is rich in biologically active substances and microelements and contains products of cellular and tissue metabolism.

Blood hydrolysates from farm animals are used as peptone substitutes in differential diagnostic nutrient media.

Other types of protein-containing raw materials of animal origin that can be used for the construction of PS include: cattle placenta and spleen, dry protein concentrate - a product of processing meat waste, split trim obtained from leather processing, poultry embryos - a waste of vaccine production, blood substitutes with expired, curd whey, soft tissues of mollusks and pinnipeds.

It is promising to use carcasses of fur-bearing animals from fur farms, cattle blood obtained at a meat processing plant, skim milk and whey (waste from creameries).

In general, PS prepared from raw materials of animal origin have a high content of basic nutritional components, are complete and balanced in amino acid composition, and have been fairly well studied.

Among products of plant origin, corn, soybeans, peas, potatoes, lupine, etc. can be used as a protein substrate for PS. However, plant agricultural raw materials contain protein, the unbalanced composition of which depends on the growing conditions of crops, as well as lipids in larger quantities than products animal origin.

A broad group consists of PSs made from protein raw materials of microbial origin (yeast, bacteria, etc.). The amino acid composition of microorganisms serving as a substrate for the preparation of PS has been well studied, and the biomass of the microorganisms used is complete in terms of nutritional composition and is characterized by an increased content of lysine and threonine.

A whole range of PSs of combined composition from protein substrates of various origins has been developed. These include casein yeast culture medium, meat yeast culture medium, etc. The basis of most known PSs are hydrolysates of casein, cattle meat and fish (up to 80%).

The share of non-food raw materials in the PS construction technology is only 15% and needs to be increased in the future.

Non-food raw materials used to obtain a nutritional base (NB) must meet certain requirements, namely:

^ complete (the quantitative and qualitative composition of the raw materials should mainly satisfy the nutritional needs of microorganisms and cells for which PSs are developed);

^ accessible (have a fairly extensive raw material base);

^ technologically advanced (the cost of implementation into production must be carried out using existing equipment or existing technology);

^ economical (the costs of introducing technology when switching to new raw materials and processing them should not exceed the cost standards for obtaining the target product);

^ standard (have long shelf life without changing physicochemical properties and nutritional value)

Periodic table

A batch cultivation system is a system in which, after introducing bacteria (inoculation) into the nutrient medium, no components are added or removed except the gas phase. It follows that a periodic system can support cell reproduction for a limited time, during which the composition of the nutrient medium changes from favorable (optimal) for their growth to unfavorable, up to the complete cessation of cell growth.

Methods for determining the total biochemical activity of soil microflora

Characteristics of microbial cellular organization

The role of microorganisms in nature and agriculture

The wide distribution of microorganisms indicates their enormous role in nature. With their participation, various organic substances decompose in soils and water bodies; they determine the circulation of substances and energy in nature; Soil fertility, the formation of coal, oil, and many other minerals depend on their activities. Microorganisms participate in the weathering of rocks and other natural processes.

Many microorganisms are used in industrial and agricultural production. Thus, baking, production of fermented milk products, winemaking, production of vitamins, enzymes, food and feed proteins, organic acids and many substances used in agriculture, industry and medicine are based on the activity of various microorganisms. The use of microorganisms in crop and livestock production is especially important. The enrichment of the soil with nitrogen, the control of crop pests with the help of microbial preparations, the proper preparation and storage of feed, the creation of feed protein, antibiotics and substances of microbial origin for animal feeding depend on them.

Microorganisms have a positive effect on the decomposition processes of substances of non-natural origin - xenobiotics, artificially synthesized, entering soils and water bodies and polluting them.

Along with beneficial microorganisms, there is a large group of so-called pathogenic, or pathogenic, microorganisms that cause various diseases of farm animals, plants, insects and humans. As a result of their vital activity, epidemics of infectious diseases in humans and animals arise, which affects the development of the economy and the productive forces of society.

Recent scientific data have not only significantly expanded the understanding of soil microorganisms and the processes they cause in the environment, but also made it possible to create new sectors in industry and agricultural production. For example, antibiotics secreted by soil microorganisms have been discovered, and the possibility of their use for the treatment of humans, animals and plants, as well as for the storage of agricultural products, has been shown. The ability of soil microorganisms to form biologically active substances has been discovered: vitamins, amino acids, plant growth stimulants - growth substances, etc. Ways have been found to use the protein of microorganisms to feed farm animals. Microbial preparations have been isolated that enhance the supply of nitrogen from the air to the soil.

The discovery of new methods for obtaining hereditarily modified forms of beneficial microorganisms has made it possible to use microorganisms more widely in agricultural and industrial production, as well as in medicine. The development of genetic, or genetic, engineering is especially promising. Its achievements ensured the development of biotechnology, the emergence of highly productive microorganisms that synthesize proteins, enzymes, vitamins, antibiotics, growth substances and other products necessary for animal husbandry and crop production.

Humanity has always come into contact with microorganisms, for millennia without even realizing it. Since time immemorial, people have observed the fermentation of dough, prepared alcoholic beverages, fermented milk, made cheese, and suffered various diseases, including epidemic ones. Evidence of the latter in the biblical books is an indication of a widespread disease (probably the plague) with recommendations to burn corpses and perform ablutions.

In accordance with the currently accepted classification, microorganisms according to the type of nutrition are divided into a number of groups depending on the sources of energy and carbon consumption. Thus, there are phototrophs, which use the energy of sunlight, and chemotrophs, for which various organic and inorganic substances serve as energy material.

Depending on the form in which microorganisms receive carbon from the environment, they are divided into two groups: autotrophic (“feeding themselves”), using carbon dioxide as the sole source of carbon, and heterotrophic (“feeding at the expense of others”), receiving carbon in the composition of rather complex reduced organic compounds.

Thus, according to the method of obtaining energy and carbon, microorganisms can be divided into photoautotrophs, photoheterotrophs, chemoautotrophs and chemoheterotrophs. Within the group, depending on the nature of the oxidized substrate, called the electron donor (H-donor), in turn, there are organotrophs that consume energy during the decomposition of organic substances, and lithotrophs (from the Greek lithos - stone), which receive energy through the oxidation of inorganic substances . Therefore, depending on the energy source and electron donor used by microorganisms, one should distinguish between photoorganotrophs, photolithotrophs, chemoorganotrophs and chemolithotrophs. Thus, there are eight possible types of nutrition.

Each group of microorganisms has a specific type of nutrition. Below is a description of the most common types of nutrition and a short list of microorganisms that carry them out.

In phototrophy, the energy source is sunlight. Photolithoautotrophy is a type of nutrition characteristic of microorganisms that use light energy to synthesize cell substances from C0 2 and inorganic compounds (H 2 0, H 2 S, S°), i.e. carrying out photosynthesis. This group includes cyanobacteria, purple sulfur bacteria and green sulfur bacteria.

Cyanobacteria (order Cyanobacteria1es), like green plants, reduce CO2 to organic matter photochemically using hydrogen from water:

C0 2 + H 2 0 light-› (CH 2 O) * + O 2

Purple sulfur bacteria (family Chromatiaceae) contain bacteriochlorophylls a and b, which determine the ability of these microorganisms to photosynthesize, and various carotenoid pigments.

To restore CO2 into organic matter, bacteria of this group use hydrogen, which is part of H25. In this case, sulfur granules accumulate in the cytoplasm, which is then oxidized to sulfuric acid:

С0 2 + 2Н 2 S light-› (СH 2 O) + Н 2 + 2S

3CO 2 + 2S + 5H 2 O light-› 3 (CH 2 0) + 2H 2 S0 4

Purple sulfur bacteria are usually obligate anaerobes.

Green sulfur bacteria (family Chlorobiaceae) contain green bacteriochlorophylls, and, in small amounts, bacteriochlorophyll, as well as various carotenoids. Like purple sulfur bacteria, they are strict anaerobes and are capable of oxidizing hydrogen sulfide, sulfides and sulfites during photosynthesis, accumulating sulfur, which in most cases is oxidized to 50^"2.

Photoorganoheterotrophy is a type of nutrition characteristic of microorganisms that, in addition to photosynthesis, can also use simple organic compounds to obtain energy. This group includes purple non-sulfur bacteria.

Purple nonsulfur bacteria (family Rhjdospirillaceae) contain bacteriochlorophylls a and b, as well as various carotenoids. They are not capable of oxidizing hydrogen sulfide (H 2 S), accumulating sulfur and releasing it into the environment.

In chemotrophy, the energy source is inorganic and organic compounds. Chemolithoautotrophy is a type of nutrition characteristic of microorganisms that obtain energy from the oxidation of inorganic compounds, such as H 2, NH 4 +, N0 2 -, Fe 2+, H 2 S, S°, S03 2 -, S 2 03 2- , CO, etc. The oxidation process itself is called chemosynthesis. The carbon for the construction of all components of chemolithoautotroph cells is obtained from carbon dioxide.

Chemosynthesis in microorganisms (iron bacteria and nitrifying bacteria) was discovered in 1887-1890. famous Russian microbiologist S.N. Vinogradsky. Chemolithoautotrophy is carried out by nitrifying bacteria (oxidize ammonia or nitrites), sulfur bacteria (oxidize hydrogen sulfide, elemental sulfur and some simple inorganic sulfur compounds), bacteria that oxidize hydrogen to water, iron bacteria capable of oxidizing divalent iron compounds, etc.

An idea of ​​the amount of energy obtained during the processes of chemolithoautotrophy caused by these bacteria is given by the following reactions:

NH3 + 11/2 0 2 - HN0 2 + H 2 0 + 2.8 10 5 J

HN0 2 + 1/2 0 2 - HN0 3 + 0.7 105 J

H 2 S + 1/2 0 2 - S + H 2 0 + 1.7 10 5 J

S + 11/2 0 2 - H 2 S0 4 + 5.0 10 5 J

H 2 + 1/ 2 0 2 - H 2 0 + 2.3 10 5 J

2FeC0 3 + 1/2 0 2 + ZN 2 0 - 2Fe (OH) 3 + 2C0 2 + 1.7 10 5 J

Chemoorganoheterotrophy is a type of nutrition characteristic of microorganisms that obtain the necessary energy and carbon from organic compounds. Among these microorganisms, many are aerobic and anaerobic species that live in soils and other substrates.