Mushrooms are aerobes or anaerobes. anaerobic bacteria

anaerobic organisms

Aerobic and anaerobic bacteria are preliminarily identified in a liquid nutrient medium by the O 2 concentration gradient:
1. Obligate aerobic(oxygen-demanding) bacteria mostly collected at the top of the tube to absorb the maximum amount of oxygen. (Exception: mycobacteria - film growth on the surface due to the wax-lipid membrane.)
2. Obligate anaerobic bacteria gather at the bottom to avoid oxygen (or not grow).
3. Optional bacteria gather mainly in the top (which is more advantageous than glycolysis), but they can be found throughout the medium, since they do not depend on O 2 .
4. Microaerophiles are collected in the upper part of the tube, but their optimum is a low concentration of oxygen.
5. Aerotolerant anaerobes do not react to oxygen concentrations and are evenly distributed throughout the test tube.

Anaerobes- organisms that receive energy in the absence of oxygen access by substrate phosphorylation, the end products of incomplete oxidation of the substrate can be oxidized to produce more energy in the form of ATP in the presence of the final proton acceptor by organisms that carry out oxidative phosphorylation.

Anaerobes are an extensive group of organisms, both micro and macro levels:

• anaerobic microorganisms- an extensive group of prokaryotes and some protozoa.
• macroorganisms - fungi, algae, plants and some animals (foraminifera class, most helminths (fluke class, tapeworms, roundworms (for example, ascaris)).

In addition, anaerobic glucose oxidation plays an important role in the work of the striated muscles of animals and humans (especially in the state of tissue hypoxia).

Classification of anaerobes

According to the classification established in microbiology, there are:

• Facultative anaerobes
• Capneistic anaerobes and microaerophiles
• Aerotolerant anaerobes
• Moderately strict anaerobes
• obligate anaerobes

If an organism is able to switch from one metabolic pathway to another (for example, from anaerobic respiration to aerobic respiration and vice versa), then it is conditionally referred to as facultative anaerobes .

Until 1991, a class was distinguished in microbiology capneistic anaerobes, requiring a low concentration of oxygen and an increased concentration of carbon dioxide (Brucella bovine type - B. abortus)

A moderately strict anaerobic organism survives in an environment with molecular O 2 but does not reproduce. Microaerophiles are able to survive and multiply in an environment with a low partial pressure of O 2 .

If the organism is not able to "switch" from anaerobic to aerobic respiration, but does not die in the presence of molecular oxygen, then it belongs to the group aerotolerant anaerobes. For example, lactic acid and many butyric bacteria

obligate anaerobes in the presence of molecular oxygen O 2 die - for example, representatives of the genus bacteria and archaea: Bacteroides, Fusobacterium, Butyrivibrio, Methanobacterium). Such anaerobes constantly live in an oxygen-deprived environment. Obligate anaerobes include some bacteria, yeasts, flagellates and ciliates.

Toxicity of oxygen and its forms for anaerobic organisms

An oxygen rich environment is aggressive towards organic life forms. This is due to the formation of reactive oxygen species in the course of life or under the influence of various forms of ionizing radiation, which are much more toxic than molecular oxygen O 2 . The factor that determines the viability of an organism in an oxygen environment is the presence of a functional antioxidant system capable of eliminating: superoxide anion (O 2 -), hydrogen peroxide (H 2 O 2), singlet oxygen (O .), and also molecular oxygen ( O 2) from the internal environment of the body. Most often, such protection is provided by one or more enzymes:

• superoxide dismutaseeliminating superoxide anion (O 2 -) without energy benefits for the body
• catalase, eliminating hydrogen peroxide (H 2 O 2) without energy benefits for the body
• cytochrome- an enzyme responsible for the transfer of electrons from NAD H to O 2. This process provides a significant energy benefit to the body.

Aerobic organisms most often contain three cytochromes, facultative anaerobes - one or two, obligate anaerobes do not contain cytochromes.

Anaerobic microorganisms can actively influence the environment, creating a suitable redox potential of the environment (eg Cl.perfringens). Some seeded cultures of anaerobic microorganisms, before starting to multiply, lower pH 2 0 from a value to , protecting themselves with a reductive barrier, others - aerotolerant - produce hydrogen peroxide during their vital activity, increasing pH 2 0.

At the same time, glycolysis is characteristic only for anaerobes, which, depending on the final reaction products, is divided into several types of fermentation:

• lactic acid fermentation Lactobacillus ,Streptococcus , Bifidobacterium, as well as some tissues of multicellular animals and humans.
• alcoholic fermentation - saccharomycetes, candida (organisms of the fungal kingdom)
• formic acid - a family of enterobacteria
• butyric - some types of clostridia
• propionic acid - propionobacteria (for example, Propionibacterium acnes)
• fermentation with release of molecular hydrogen - some species of Clostridium, Stickland fermentation
• methane fermentation - for example, Methanobacterium

As a result of the breakdown of glucose, 2 molecules are consumed, and 4 molecules of ATP are synthesized. Thus, the total ATP yield is 2 ATP molecules and 2 NAD·H 2 molecules. The pyruvate obtained during the reaction is utilized by the cell in different ways, depending on what type of fermentation it follows.

Antagonism of fermentation and decay

In the process of evolution, the biological antagonism of the fermentative and putrefactive microflora was formed and consolidated:

The breakdown of carbohydrates by microorganisms is accompanied by a significant decrease in the environment, while the breakdown of proteins and amino acids is accompanied by an increase (alkalinization). The adaptation of each of the organisms to a certain reaction of the environment plays an important role in nature and human life, for example, due to fermentation processes, rotting of silage, fermented vegetables, and dairy products is prevented.

Cultivation of anaerobic organisms

Isolation of pure culture of anaerobes schematically

The cultivation of anaerobic organisms is mainly the task of microbiology.

For the cultivation of anaerobes, special methods are used, the essence of which is to remove air or replace it with a specialized gas mixture (or inert gases) in sealed thermostats. - anaerostats .

Another way to grow anaerobes (most often microorganisms) on nutrient media is the addition of reducing substances (glucose, sodium formic acid, etc.), which reduce the redox potential.

Common growth media for anaerobic organisms

For general environment Wilson - Blair the base is agar-agar with the addition of glucose, sodium sulfite and ferrous chloride. Clostridia form black colonies on this medium by reducing sulfite to sulfide anion, which combines with iron (II) cations to give a black salt. As a rule, black colony formations appear in the depth of the agar column on this medium.

Wednesday Kitta - Tarozzi consists of meat-peptone broth, 0.5% glucose and pieces of liver or minced meat to absorb oxygen from the environment. Before sowing, the medium is heated in a boiling water bath for 20-30 minutes to remove air from the medium. After sowing, the nutrient medium is immediately filled with a layer of paraffin or paraffin oil to isolate it from oxygen access.

General culture methods for anaerobic organisms

Gaspack- the system chemically ensures the constancy of the gas mixture acceptable for the growth of most anaerobic microorganisms. In a sealed container, water reacts with sodium borohydride and sodium bicarbonate tablets to form hydrogen and carbon dioxide. The hydrogen then reacts with the oxygen of the gas mixture on a palladium catalyst to form water, which is already re-reacting with the hydrolysis of the borohydride.

This method was proposed by Brewer and Olgaer in 1965. The developers introduced a disposable hydrogen generating sachet, which was later upgraded to carbon dioxide generating sachets containing an internal catalyst.

Zeissler method used to isolate pure cultures of spore-forming anaerobes. To do this, inoculate on the Kitt-Tarozzi medium, heat it for 20 minutes at 80 ° C (to destroy the vegetative form), fill the medium with vaseline oil and incubate for 24 hours in a thermostat. Then, seeding is carried out on sugar-blood agar to obtain pure cultures. After a 24-hour cultivation, the colonies of interest are studied - they are subcultured on the Kitt-Tarozzi medium (with subsequent control of the purity of the isolated culture).

Fortner method

Fortner method- inoculations are made on a Petri dish with a thickened layer of the medium, divided in half by a narrow groove cut in the agar. One half is seeded with a culture of aerobic bacteria, the other half is inoculated with anaerobic bacteria. The edges of the cup are filled with paraffin and incubated in a thermostat. Initially, the growth of the aerobic microflora is observed, and then (after the absorption of oxygen), the growth of the aerobic microflora stops abruptly and the growth of the anaerobic microflora begins.

Weinberg method used to obtain pure cultures of obligate anaerobes. Cultures grown on Kitta-Tarozzi medium are transferred to sugar broth. Then, with a disposable Pasteur pipette, the material is transferred into narrow tubes (Vignal tubes) with sugar meat-peptone agar, immersing the pipette to the bottom of the tube. The inoculated tubes are rapidly cooled, which makes it possible to fix the bacterial material in the thickness of the hardened agar. The tubes are incubated in a thermostat, and then the grown colonies are studied. When a colony of interest is found, a cut is made in its place, the material is quickly taken and inoculated on the Kitta-Tarozzi medium (with subsequent control of the purity of the isolated culture).

Peretz Method

Peretz Method- a culture of bacteria is introduced into the melted and cooled sugar agar-agar and poured under glass placed on cork sticks (or fragments of matches) in a Petri dish. The method is the least reliable of all, but it is quite simple to use.

Differential - diagnostic nutrient media

• environments gissa("variegated row")
• Wednesday Ressel(Russell)
• Wednesday Ploskireva or baktoagar "Zh"
• Bismuth Sulfite Agar

Hiss media: To 1% peptone water, add a 0.5% solution of a certain carbohydrate (glucose, lactose, maltose, mannitol, sucrose, etc.) and Andrede's acid-base indicator, pour into test tubes into which a float is placed to trap gaseous products formed during decomposition of hydrocarbons.

Ressel Wednesday(Russell) is used to study the biochemical properties of enterobacteria (Shigella, Salmonella). Contains nutrient agar-agar, lactose, glucose and indicator (bromothymol blue). The color of the medium is grassy green. Usually prepared in 5 ml tubes with a beveled surface. Sowing is carried out by an injection into the depth of the column and a stroke along the beveled surface.

Wednesday Ploskirev(Bactoagar Zh) is a differential diagnostic and selective medium, since it inhibits the growth of many microorganisms and promotes the growth of pathogenic bacteria (causative agents of typhoid, paratyphoid, dysentery). Lactose-negative bacteria form colorless colonies on this medium, while lactose-positive bacteria form red colonies. Medium contains agar, lactose, brilliant green, bile salts, mineral salts, indicator (neutral red).

Bismuth Sulfite Agar It is designed to isolate salmonella in its pure form from infected material. Contains tryptic digest, glucose, salmonella growth factors, brilliant green and agar. The differential properties of the medium are based on the ability of Salmonella to produce hydrogen sulfide, on their resistance to the presence of sulfide, brilliant green and bismuth citrate. Colonies are marked in black color of bismuth sulfide (the technique is similar to the medium Wilson - Blair).

Metabolism of anaerobic organisms

The metabolism of anaerobic organisms has several distinct subgroups:

Anaerobic energy metabolism in tissues human and animals

Anaerobic and aerobic energy production in human tissues

Some tissues of animals and humans are characterized by increased resistance to hypoxia (especially muscle tissue). Under normal conditions, ATP synthesis occurs aerobically, and during intense muscular activity, when oxygen delivery to the muscles is difficult, in a state of hypoxia, as well as during inflammatory reactions in tissues, anaerobic mechanisms of ATP regeneration dominate. In skeletal muscles, 3 types of anaerobic and only one aerobic pathway of ATP regeneration have been identified.

3 types of anaerobic ATP synthesis pathway

Anaerobic include:

• Creatine phosphatase (phosphogenic or alactate) mechanism - rephosphorylation between creatine phosphate and ADP
• Myokinase - synthesis (otherwise resynthesis) ATP in the reaction of transphosphorylation of 2 molecules of ADP (adenylate cyclase)
• Glycolytic - anaerobic breakdown of blood glucose or glycogen stores, ending with the formation

Anaerobes I Anaerobes (Greek negative prefix an- + aēr + b life)

microorganisms that develop in the absence of free oxygen in their environment. They are found in almost all samples of pathological material in various purulent-inflammatory diseases, they are conditionally pathogenic, sometimes pathogenic. Distinguish facultative and obligate A. Facultative A. are able to exist and multiply both in oxygen and in an oxygen-free environment. These include coli, Yersinia, Streptococcus, and other Bacteria .

Obligate A. die in the presence of free oxygen in the environment. They are divided into two groups: those that form, or clostridia, and bacteria that do not form spores, or the so-called non-clostridial anaerobes. Among clostridia, causative agents of anaerobic clostridial infections are distinguished - botulism, clostridial wound infection, tetanus. Non-clostridial A. include gram-negative and gram-positive rod-shaped or spherical bacteria: fusobacteria, veillonella, peptococci, peptostreptococci, propionibacteria, eubacteria, etc. Non-clostridial A. are an integral part of the normal microflora of humans and animals, but at the same time play an important role in the development of such purulent-inflammatory processes as lung and brain abscesses, pleural empyema, phlegmon of the maxillofacial region, otitis media, etc. Most anaerobic infections (Anaerobic infection) , caused by non-clostridial anaerobes, refers to endogenous and develops mainly with a decrease in the body's resistance as a result of surgery, cooling, impaired immunity.

The main part of clinically significant A. are bacteroids and fusobacteria, peptostreptococci and spore Gram-positive rods. Bacteroides account for about half of purulent-inflammatory processes caused by anaerobic bacteria.

Bibliography: Laboratory research methods in the clinic, ed. V.V. Menshikov. M., 1987.

1. Small medical encyclopedia. - M.: Medical Encyclopedia. 1991-96 2. First aid. - M.: Great Russian Encyclopedia. 1994 3. Encyclopedic dictionary of medical terms. - M.: Soviet Encyclopedia. - 1982-1984.

See what "Anaerobes" are in other dictionaries:

Modern Encyclopedia

- (anaerobic organisms) are able to live in the absence of atmospheric oxygen; some types of bacteria, yeast, protozoa, worms. Energy for life is obtained by oxidizing organic, less often inorganic substances without the participation of free ... ... Big Encyclopedic Dictionary

- (gr.). Bacteria and similar lower animals, capable of living only in the complete absence of atmospheric oxygen. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. anaerobes (see anaerobiosis) otherwise anaerobionts, ... ... Dictionary of foreign words of the Russian language

Anaerobes- (from the Greek an negative particle, aer air and bios life), organisms that can live and develop in the absence of free oxygen; some types of bacteria, yeast, protozoa, worms. Obligate, or strict, anaerobes develop ... ... Illustrated Encyclopedic Dictionary

- (from a ..., an ... and aerobes), organisms (microorganisms, mollusks, etc.) that can live and develop in an oxygen-free environment. The term was introduced by L. Pasteur (1861), who discovered butyric fermentation bacteria. Ecological encyclopedic dictionary. ... ... Ecological dictionary

Organisms (mainly prokaryotes) that can live in the absence of free oxygen in the environment. Obligate A. receive energy as a result of fermentation (butyric acid bacteria, etc.), anaerobic respiration (methanogens, sulfate-reducing bacteria ... Dictionary of microbiology

Abbr. name anaerobic organisms. Geological dictionary: in 2 volumes. M.: Nedra. Edited by K. N. Paffengolts et al. 1978 ... Geological Encyclopedia

ANAEROBES- (from Greek a negative frequent, aer air and bios life), microscopic organisms that can draw energy (see Anaerobiosis) not in oxidation reactions, but in splitting reactions of both organic and inorganic compounds (nitrates, sulfates and etc … Big Medical Encyclopedia

ANAEROBES Organisms that develop normally in the complete absence of free oxygen. In nature, A. are found everywhere where organic matter decomposes without access to air (in deep layers of soil, especially waterlogged soil, in manure, silt, etc.). There are… Pond fish farming

Ow, pl. (unit anaerobe, a; m.). Biol. Organisms capable of living and developing in the absence of free oxygen (cf. aerobes). ◁ Anaerobic, oh, oh. Ah, bacteria. Ah, the infection. * * * anaerobes (anaerobic organisms), able to live in the absence of ... ... encyclopedic Dictionary

- (anaerobic organisms), organisms that can live and develop only in the absence of free oxygen. They receive energy due to the oxidation of organic or (less commonly) inorganic substances without the participation of free oxygen. To anaerobes ... ... Biological encyclopedic dictionary

Bacteria are present everywhere in our world. They are everywhere and everywhere, and the number of their varieties is simply amazing.

Depending on the need for the presence of oxygen in the nutrient medium for the implementation of vital activity, microorganisms are classified into the following types.

• Obligate aerobic bacteria, which are collected in the upper part of the nutrient medium, the flora contained the maximum amount of oxygen.
• Obligate anaerobic bacteria, which are located in the lower part of the environment, as far as possible from oxygen.
• Facultative bacteria mainly live in the upper part, but can be distributed throughout the environment, as they do not depend on oxygen.
• Microaerophiles prefer a low concentration of oxygen, although they gather in the upper part of the environment.
• Aerotolerant anaerobes are evenly distributed in the nutrient medium, insensitive to the presence or absence of oxygen.

The concept of anaerobic bacteria and their classification

The term "anaerobes" appeared in 1861, thanks to the work of Louis Pasteur.

Anaerobic bacteria are microorganisms that develop regardless of the presence of oxygen in the nutrient medium. They get energy by substrate phosphorylation. There are facultative and obligate aerobes, as well as other types.

The most significant anaerobes are bacteroides

The most important aerobes are bacteroids. About fifty percent of all purulent-inflammatory processes, the causative agents of which can be anaerobic bacteria, are bacteroids.

Bacteroides are a genus of Gram-negative obligate anaerobic bacteria. These are rods with bipolar coloration, the size of which does not exceed 0.5-1.5 by 15 microns. They produce toxins and enzymes that can cause virulence. Different bacteroids have different resistance to antibiotics: there are both resistant and susceptible to antibiotics.

Energy production in human tissues

Some tissues of living organisms have increased resistance to low oxygen content. Under standard conditions, the synthesis of adenosine triphosphate occurs aerobically, but with increased physical exertion and inflammatory reactions, the anaerobic mechanism comes to the fore.

Adenosine triphosphate (ATP) It is an acid that plays an important role in the body's energy production. There are several options for the synthesis of this substance: one aerobic and as many as three anaerobic.

Anaerobic mechanisms of ATP synthesis include:

• rephosphorylation between creatine phosphate and ADP;
• transphosphorylation reaction of two ADP molecules;
• anaerobic breakdown of blood glucose or glycogen stores.

Cultivation of anaerobic organisms

There are special methods for growing anaerobes. They consist in replacing air with gas mixtures in sealed thermostats.

Another way is to grow microorganisms in a nutrient medium to which reducing substances are added.

Culture media for anaerobic organisms

There are common nutrient media and differential diagnostic nutrient media. Common ones include the Wilson-Blair medium and the Kitt-Tarozzi medium. For differential diagnostic - Hiss medium, Ressel medium, Endo medium, Ploskirev medium and bismuth-sulfite agar.

The basis for the Wilson-Blair medium is agar-agar with the addition of glucose, sodium sulfite and iron dichloride. Black colonies of anaerobes are formed mainly in the depth of the agar column.

Ressel's (Russell's) medium is used in the study of the biochemical properties of bacteria such as Shigella and Salmonella. It also contains agar-agar and glucose.

Wednesday Ploskirev inhibits the growth of many microorganisms, so it is used for differential diagnostic purposes. In such an environment, pathogens of typhoid fever, dysentery and other pathogenic bacteria develop well.

The main purpose of bismuth sulfite agar is the isolation of salmonella in its pure form. This environment is based on the ability of Salmonella to produce hydrogen sulfide. This medium is similar to the Wilson-Blair medium in the technique used.

Anaerobic infections

Most anaerobic bacteria living in the human or animal body can cause various infections. As a rule, infection occurs during a period of weakened immunity or a violation of the general microflora of the body. There is also the possibility of infection pathogens from the external environment, especially in late autumn and winter.

Infections caused by anaerobic bacteria are usually associated with the flora of the human mucous membranes, that is, with the main habitats of anaerobes. Typically, these infections multiple triggers at once(to 10).

The exact number of diseases caused by anaerobes is almost impossible to determine due to the difficulty in collecting materials for analysis, transporting samples, and cultivating the bacteria themselves. Most often, this type of bacteria is found in chronic diseases.

Anaerobic infections affect people of all ages. At the same time, the level of infectious diseases in children is higher.

Anaerobic bacteria can cause various intracranial diseases (meningitis, abscesses, and others). Distribution, as a rule, occurs with the blood stream. In chronic diseases, anaerobes can cause pathologies in the head and neck: otitis media, lymphadenitis, abscesses. These bacteria are dangerous to both the gastrointestinal tract and the lungs. With various diseases of the urogenital female system, there is also a risk of developing anaerobic infections. Various diseases of the joints and skin can be the result of the development of anaerobic bacteria.

Causes of anaerobic infections and their symptoms

Infections are caused by all processes during which active anaerobic bacteria enter the tissues. Also, the development of infections can cause impaired blood supply and tissue necrosis (various injuries, tumors, edema, vascular disease). Mouth infections, animal bites, lung diseases, pelvic inflammatory disease and many other diseases can also be caused by anaerobes.

In different organisms, the infection develops in different ways. This is influenced by the type of pathogen, and the state of human health. Because of the difficulties associated with diagnosing anaerobic infections, the conclusion is often based on assumptions. Differ in some features of the infection caused by non-clostridial anaerobes.

The first signs of infection of tissues with aerobes are suppuration, thrombophlebitis, gas formation. Some tumors and neoplasms (intestinal, uterine and others) are also accompanied by the development of anaerobic microorganisms. With anaerobic infections, an unpleasant odor may appear, however, its absence does not exclude anaerobes as the causative agent of the infection.

Features of obtaining and transporting samples

The very first study in determining infections caused by anaerobes is a visual inspection. Various skin lesions are a common complication. Also, evidence of the vital activity of bacteria will be the presence of gas in infected tissues.

For laboratory research and establishing an accurate diagnosis, first of all, it is necessary to competently get matter sample from the affected area. For this, a special technique is used, thanks to which normal flora does not get into the samples. The best method is aspiration with a straight needle. Obtaining laboratory material by smears is not recommended, but possible.

Samples not suitable for further analysis include:

• sputum obtained by self-excretion;
• samples obtained during bronchoscopy;
• smears from the vaginal vaults;
• urine with free urination;
• feces.

For research can be used:

• blood;
• pleural fluid;
• transtracheal aspirates;
• pus obtained from the abscess cavity;
• cerebrospinal fluid;
• lung punctures.

Transport samples it is necessary as soon as possible in a special container or plastic bag with anaerobic conditions, since even a short-term interaction with oxygen can cause the death of bacteria. Liquid samples are transported in a test tube or in syringes. Swabs with samples are transported in test tubes with carbon dioxide or pre-prepared media.

Treatment of anaerobic infection

In the case of diagnosing an anaerobic infection for adequate treatment, it is necessary to follow the following principles:

• toxins produced by anaerobes must be neutralized;
• the habitat of bacteria should be changed;
• the spread of anaerobes must be localized.

To comply with these principles antibiotics are used in treatment, which affect both anaerobes and aerobic organisms, since often the flora in anaerobic infections is mixed. At the same time, when prescribing drugs, the doctor must evaluate the qualitative and quantitative composition of the microflora. The agents that are active against anaerobic pathogens include: penicillins, cephalosporins, champhenicol, fluoroquinolo, metranidazole, carbapenems and others. Some drugs have a limited effect.

To control the habitat of bacteria, in most cases, surgical intervention is used, which is expressed in the treatment of affected tissues, drainage of abscesses, and ensuring normal blood circulation. Surgical methods should not be ignored because of the risk of life-threatening complications.

Sometimes used ancillary therapies, and also because of the difficulties associated with the exact determination of the causative agent of the infection, empirical treatment is used.

With the development of anaerobic infections in the oral cavity, it is also recommended to add as many fresh fruits and vegetables to the diet as possible. The most useful are apples and oranges. The restriction is subjected to meat food and fast food.

Anaerobic bacteria are those that, unlike aerobic bacteria, are able to survive and grow in an environment with little or no oxygen. Many of these microorganisms live on the mucous membranes (in the mouth, in the vagina) and in the human intestine, becoming the cause of infection when tissues are damaged.

Sinusitis, mouth infections, acne, otitis media, gangrene, and abscesses are some of the best-known diseases and conditions that such bacteria lead to. They can also enter from the outside through a wound or when eating contaminated food, causing such terrible diseases as botulism,. But in addition to harm, some species benefit humans, for example, by converting vegetable sugars that are toxic to it into useful ones for fermentation in the colon. Also, anaerobic bacteria, along with aerobic ones, play an important role in the ecosystem, taking part in the decomposition of the remains of living beings, but not as big as mushrooms in this regard.

Classification

Anaerobic bacteria, in turn, are divided into 3 groups according to oxygen tolerance and need for it:

• Optional - able to grow aerobically or anaerobically, i.e. in the presence or absence of O2.
• Microaerophiles - require low oxygen concentration (eg 5%), and many of them require high CO 2 concentration (eg 10%); in the complete absence of oxygen, they grow very weakly.
• Obligatory (mandatory, strict) – are incapable of aerobic metabolism (grow in the presence of oxygen), but have different tolerance to O 2 (the ability to survive for some time).

Obligate anaerobes breed in areas of low redox potential (eg, in necrotic, dead tissue). Oxygen is toxic to them. There is a classification according to its portability:

• Strict - withstand only ≤0.5% O 2 in air.
• Moderate - 2-8% O 2.
• Aerotolerant anaerobes - tolerate atmospheric O2 for a limited time.

The average percentage of oxygen in the earth's atmosphere is 21.

Examples of strict anaerobic bacteria

obligate anaerobic bacteria , which commonly cause infections can tolerate atmospheric O 2 for a minimum of 8 hours and often up to 3 days. They are the main components of the normal microflora on the mucous membranes, especially in the mouth, lower gastrointestinal tract and vagina; these bacteria cause disease when normal mucosal barriers are disrupted.

Gram-negative anaerobes

• Bacteroids or lat. Bacteroides (most common): intra-abdominal infections;
• Fusobacterium: abscesses, wound infections, pulmonary and intracranial infections;
• Profiromonas or Porphyromonas: aspiration pneumonia and periodontitis;
• Prevotella or Prevotella: intra-abdominal and soft tissue infections.

Gram-positive anaerobes and some of the infections they cause include:

• Actinomyces or Actinomyces: infections in the head and neck, abdominal and pelvic, as well as aspiration pneumonia (actinomycosis);
• Clostridium or Clostridium: intra-abdominal infections (eg, clostridial necrotizing enteritis), soft tissue infections, and gas gangrene caused by C. perfringens; food poisoning due to C. perfringens type A; botulism due to C. botulinum; tetanus due to C. tetani; Difficile - induced diarrhea (pseudomembranous colitis);
• Peptostreptococcus or Peptostreptococcus: oral, respiratory and intra-abdominal infections;
• Propionobacteria or Propionibacterium - foreign body infections (eg, in CSF bypass, prosthetic joint, or heart device).

Anaerobic infections are usually purulent, causing abscess formation and tissue necrosis, and sometimes septic thrombophlebitis or gas, or both. Many anaerobes produce tissue-degrading enzymes, as well as some of the most potent paralytic toxins known today.

For example, botulinum toxin, produced by the bacteria Clostridium botulinum, which causes botulism in humans, is used in cosmetics as injections to smooth wrinkles, as it paralyzes the subcutaneous muscles.

Usually, several types of anaerobes are present in infected tissues, and aerobes (polymicrobial or mixed infections) are often also present.

Signs that an infection is caused by anaerobic bacteria:

• Polymicrobial results by Gram stain or bacterial plating.
• Gas formation in purulent or infected tissues.
• Purulent odor from infected tissues.
• Necrosis (death) of infected tissues.
• The site of infection near the mucous membrane, where anaerobic microflora is usually found.

Diagnostics

Samples of anaerobic culture should be obtained by aspiration or biopsy from areas that do not normally contain them. Delivery to the laboratory must be prompt, and transport equipment must provide an anoxic environment with carbon dioxide, hydrogen, and nitrogen. Swabs are best transported in an anaerobically sterilized semi-solid medium such as Cary-Blair transport medium (a special solution that contains a minimum of nutrients to grow bacteria and substances that can kill them).

Anaerobes are bacteria that appeared on planet Earth before other living organisms.

They play an important role in the ecosystem, are responsible for the vital activity of living beings, participate in the process of fermentation and decomposition.

At the same time, anaerobes cause the development of dangerous diseases and inflammatory processes.

What are anaerobes

Under anaerobes, it is customary to understand micro- and macro-organisms that are able to live in the absence of oxygen. They receive energy as a result of the process of substrate phosphorylation.

The development and reproduction of anaerobes occurs in purulent-inflammatory foci, affecting people with weak immunity.

Classification of anaerobes

There are two types of these bacteria:

• Facultative, which are able to live, develop and reproduce in both oxygen and oxygen-free environments. Such microorganisms include staphylococci, Escherichia coli, streptococci, shigella;
• Obligate live only in an environment where there is no oxygen. If this element appears in the environment, then obligate anaerobes die.

In turn, obligate anaerobes are divided into two groups:

• Clostridia are bacteria that form spores; excite the development of infections - butulism, wound, tetanus.
• Non-clostridial - bacteria that are not able to form spores. They live in the microflora of people and animals, are not dangerous to living beings. These bacteria include eubacteria, peillonella, peptococci, bacterioids.

Often, non-clostridial anaerobes cause purulent and inflammatory processes, including peritonitis, pneumonia, sepsis, otitis, etc. All infections caused by this type of bacteria occur under the influence of internal causes. The main factor in the development of infections is a decrease in immunity and body resistance to pathogenic microbes. This usually happens after operations, injuries, hypothermia.

Examples of anaerobes

Prokaryotes and protozoa. Mushrooms. Seaweed. Plants. Helminths are flukes, tapeworms and roundworms. Infections - intra-abdominal, intracranial, pulmonary, wound, abscesses, in the neck and head, soft tissues, cerebrospinal fluid. Aspiration pneumonia. Periodontitis.

Infections that are provoked by anaerobic bacteria cause the development of necrosis, the formation of an abscess, sepsis and gas formation. A lot of anaerobes create enzymes in tissues that produce paralytic toxins.

Anaerobic bacteria cause the development of the following diseases: Infections of the oral cavity. Sinusitis. Acne. Inflammation of the middle ear. Gangrene. Botulism. Tetanus. In addition to the dangers, anaerobes are beneficial to humans. In particular, they convert harmful toxic sugars into beneficial enzymes in the colon.

Differences between anaerobes and aerobes

Anaerobes mainly live in an environment where there is no oxygen, while aerobes are able to live, develop and multiply only in the presence of oxygen. Anaerobes include birds, fungi, several types of fungi, and animals. Oxygen in anaerobes takes part in all life processes, which contributes to the formation and production of energy.

Recently, scientists from the Netherlands discovered that anaerobes living at the bottom of water bodies can oxidize methane. In this case, the reduction of nitrates and nitrites, which release molecular nitrogen. Archaeobacteria and eubacteria take part in the formation of this substance.

Microbiologists are engaged in the cultivation of anaerobic microorganisms. This process requires a specific microflora and a certain degree of concentration of metabolites.

Anaerobes are grown on nutrients - glucose, sodium sulfate, casein.

Anaerobes have a different metabolism, which allows us to distinguish several subgroups of bacteria on this basis. These are organisms that use anaerobic respiration, solar radiation energy, catabolism of macromolecular compounds.

Anaerobic processes are used to decompose and decontaminate sewage sludge, to ferment sugars to produce ethyl alcohol.

conclusions

Anaerobes can bring both benefit and harm to humans, animals and plants. If conditions are formed for the development of pathogenic processes, then anaerobes will provoke infections and diseases that can be fatal. In industry and microbiology, scientists are trying to use the anaerobic properties of bacteria to obtain useful enzymes, purify water and soil.