Biological factors affecting microorganisms presentation presentation. Influence of environmental conditions on microorganisms

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Microbiology, the spread of microbes in nature Lecturer: Egorova.M.A Prepared by:Morozova.K.A

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Microbes, and primarily bacteria, are much more widespread in nature than other living beings. Due to the exceptional diversity of nutrient absorption, small size and easy adaptability to various environmental conditions, bacteria can be found where other life forms are absent.

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Soil microflora The number of microbes in the soil is enormous: hundreds of millions and billions of individuals in 1 g of soil. Soil is much richer in microbes than water and air. Soil is the main reservoir from which microbes enter water and air. Microbes are most populated by cultivated and fertilized soils, there are several billion of them per 1 g. The soils of forests and swamps are relatively poor in bacteria, they contain quite a lot of fungal forms. According to the latest data, even in the soils of sandy deserts there are hundreds of millions of bacteria in 1 g. The surface layer of the soil is relatively poor in microbes, since microbes in it are not protected from direct sunlight and drying. The main mass of the microbial population is located at a depth of 15-20 cm. But with increasing depth, their number decreases, however, at a depth of several meters, a certain number of bacteria are found. The soil adsorbs microbial cells and does not let them into the depths. Soil layers, like a natural filter, protect groundwater from microbial contamination. There are a wide variety of physiological groups of microbes in the soil: aerobes, anaerobes, putrefactive, nitrifying, nitrogen-fixing, fiber-decomposing, sulfur bacteria, spore and non-spore, etc. Microbes are one of the main factors in soil formation.

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Antagonistic relationships between microbes are widespread in the soil. It was from soil microbes that the most active antibiotics were isolated - penicillin, streptomycin, etc. Microbiological study of the soil is important in the construction of houses, premises for animals, reservoirs, etc.

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Water microflora Water, like soil, is a natural habitat for many microbes. The bulk of microbes comes from the soil, which is why the microflora of water largely reflects the microflora of the soil in contact with water. The number of microbes in 1 ml of water depends on the presence of nutrients in it. The more polluted water is with organic residues, the more microbes it contains. The cleanest are the waters of deep artesian wells, as well as spring waters. They usually do not contain germs. Open reservoirs and rivers are especially rich in microbes. The largest number of microbes in them is in the surface layers (in a layer of 10 cm from the water surface) of coastal zones. With distance from the coast and increasing depth, the number of microbes decreases. In pure water there are 100-200 microbial cells in 1 ml, and in contaminated water - 100-300 thousand or more.

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River silt is richer in microbes than river water. There are so many bacteria in the very surface layer of silt that a kind of film is formed from them. This film contains many filamentous sulfur bacteria, iron bacteria, they oxidize hydrogen sulfide to sulfuric acid and thus prevent the inhibitory effect of hydrogen sulfide (fish death is prevented). There are also many nitrifying, nitrogen-fixing, fiber-decomposing and other microbes in it. In water, most of all non-spore-bearing bacteria (97%), and in sludge - spore-bearing (75%). In terms of species composition, the water microflora has much in common with the soil microflora, but there are also bacteria that have adapted to permanent residence in water (Bact. fluorescens, Bact. aquatilis, Micrococcus candicans, etc.). Rain water and fallen snow are rather poor in microbes. Some types of vibrios, spirilla, iron and sulfur bacteria live only in water bodies.

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The number of microbes in the seas and oceans is quite large, but less than in fresh waters. Most microbes in coastal areas. Various types of bacteria are found in the soil of the oceans at a depth of 10 km, where the pressure reaches 700-1000 atmospheres. Among them are found all the usual physiological groups of microbes. A. E. Criss found at all depths of the Black Sea, the Pacific Ocean, and in the Arctic waters new filamentous-cuminate microorganisms, in their properties occupying an intermediate position between protozoa and bacteria. Rivers in urban areas are often natural recipients of household and fecal sewage, so the number of microbes sharply increases within the boundaries of settlements. But as the river moves away from the city, the number of microbes gradually decreases, and after 3-4 tens of kilometers it again approaches its original value. This self-purification of water depends on a number of factors: mechanical sedimentation of microbial bodies; reduction in water of nutrients assimilated by microbes; the action of the direct rays of the sun; consumption of bacteria by protozoa, etc.

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If we assume that a bacterial cell has a volume of 1 micron, then if they are contained in the amount of 1000 cells per 1 ml, you will get about a ton of live bacterial mass in a cubic kilometer of water. Such a mass of bacteria carries out various transformations in the circulation of substances in water bodies and is the initial link in the fish food chain. Pathogenic microbes can enter rivers and reservoirs with sewage. Brucellosis bacillus, tularemia bacillus, poliomyelitis virus, foot-and-mouth disease virus, as well as causative agents of intestinal infections - typhoid bacillus, paratyphoid bacillus, dysentery bacillus, vibrio cholerae - can remain in water for a long time, and water can become a source of infectious diseases. Especially dangerous is the ingress of pathogenic microbes into the water supply network, which happens when it malfunctions. Therefore, sanitary biological control has been established for the state of reservoirs and the tap water supplied from them.

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Air microflora Air microflora depends on the microflora of the soil or water, above which the air layers are located. Microbes can multiply in soil and water, but they do not multiply in the air, but only persist for some time. Raised into the air with dust, they either settle with drops back to the surface of the earth, or die in the air from a lack of nutrition and from the action of ultraviolet rays. Therefore, the air microflora is less abundant than the soil and water microflora. The largest number of microbes contains the air of industrial cities. The air in rural areas is much cleaner. The cleanest air is over forests, mountains, snowy expanses. The upper layers of the air contain fewer germs. Above Moscow at an altitude of 500 m, one liter of air contains 2-3 bacteria, at an altitude of 1000 m - 1 bacterium and at an altitude of 2000 m - 0.5. But bacteria were also found at an altitude of 10 thousand meters. In summer, the air is most polluted with microbes, in winter it is the cleanest.

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The microflora of the air is different in that it contains a lot of pigmented, as well as spore-bearing bacteria, as they are more resistant to ultraviolet rays (sarcinas, staphylococci, pink yeast, miraculous bacillus, hay bacillus, etc.). The indoor air is very rich in microbes, especially in cinemas, railway stations, schools, livestock buildings etc. They are often found in 1 cubic meter. m. from 5 to 300 thousand bacteria, with a more abundant microflora observed in winter. Together with harmless saprophytes in the air, especially enclosed spaces, there may also be pathogenic microbes: tubercle bacillus, streptococci, staphylococci, pathogens of influenza, whooping cough, etc. Influenza, measles, whooping cough are infected exclusively by airborne droplets. When coughing, sneezing, the smallest droplets are thrown into the air - aerosols containing pathogens that other people inhale and, having become infected, fall ill.

Microorganisms

• Microorganisms, (microbes) - the name of a collective group of living organisms that are too small to be visible to the naked eye (their characteristic size is less than 0.1 mm). Microorganisms include both non-nuclear (prokaryotes: bacteria, archaea) and eukaryotes: some fungi, protists, but not viruses, which are usually isolated into a separate group. Most microorganisms consist of a single cell, but there are also multicellular microorganisms, just as there are some unicellular macroorganisms visible to the naked eye. Microbiology is the study of these organisms.

General information

• The ubiquity and total power of the metabolic potential of microorganisms determines their most important role in the circulation of substances and maintaining dynamic balance in the Earth's biosphere.
• Brief review various representatives microcosm, occupying certain "floors" of size, shows that, as a rule, the size of objects is definitely related to their structural complexity. The lower size limit for a free-living single-celled organism is determined by the space required to pack inside the cell the apparatus necessary for independent existence. The limitation of the upper limit of the size of microorganisms is determined, according to modern concepts, by the relationship between the cell surface and volume. With an increase in cellular dimensions, the surface increases in the square, and the volume in the cube, so the ratio between these values ​​shifts towards the latter.

Habitat

• Microorganisms live almost everywhere where there is water, including hot springs, the bottom of the world's oceans, and also deep inside the earth's crust. They are an important link in the metabolism in ecosystems, mainly acting as decomposers, but in some ecosystems they are the only producers of biomass. Microorganisms that live in water participate in the cycle of sulfur, iron and other elements, decompose organic matter of animal and vegetable origin, and provide self-purification of water in reservoirs. However, not all microorganisms benefit humans. Some microorganisms are opportunistic or pathogenic for humans and animals. Some microorganisms cause damage to agricultural products, lead to depletion of the soil with nitrogen, cause pollution of water bodies, and the accumulation of toxic substances (for example, microbial toxins). Microorganisms are characterized by good adaptability to the action of factors external environment. Various microorganisms can grow at temperatures from −6° to +50-75°. The record for survival at elevated temperatures was set by archaebacteria, which live at a temperature of about 300 °. This temperature is created by pressure in hot springs at the bottom of the ocean. There are microorganisms that exist at an increased level of ionizing radiation, at any pH value, at 25% sodium chloride concentration, under conditions of varying oxygen content up to its complete absence.
• At the same time, pathogenic microorganisms cause diseases in humans and animals and plants.
• The most widely accepted theories about the origin of life on Earth postulate that protomicroorganisms were the first living organisms to emerge through evolution.

• Thanks to the advances in biochemistry of microorganisms and especially the development genetics of microorganisms And molecular genetics It was found that many processes of biosynthesis and energy metabolism (electron transport, the tricarboxylic acid cycle, the synthesis of nucleic acids and proteins, etc.) proceed in microorganisms in the same way as in the cells of higher plants and animals. Thus, the growth, development, and reproduction of both higher and lower forms of life are based on the same processes. Along with this, microorganisms have specific enzyme systems and biochemical reactions that are not observed in other creatures. This is the basis for the ability of microorganisms to decompose cellulose, lignin, chitin, petroleum hydrocarbons, keratin, wax, etc. Microorganisms have extremely diverse ways of obtaining energy. Chemoautotrophs get it due to the oxidation of inorganic substances, photoautotrophic bacteria use light energy in that part of the spectrum that is inaccessible to higher plants, etc. Some microorganisms are able to assimilate molecular nitrogen (see. Nitrogen-fixing microorganisms ), synthesize protein from a variety of carbon sources, produce a variety of biologically active substances (antibiotics, enzymes, vitamins, growth stimulants, toxins, etc.). Application Microorganisms in page - x. practice and industry is based on these specific features of their metabolism.

• PATIENT MICROORGANISMS (pathogenic microorganisms), viruses, rickettsia, bacteria, microscopic pathogenic fungi, protozoa, causing various infectious diseases when they enter the human and animal body. Viruses cause influenza, measles, scarlet fever, poliomyelitis, hepatitis, AIDS, etc.; rickettsia- typhus. Among bacteria strepto- and staphylococci are the cause of purulent processes, sepsis (blood poisoning); meningococci infect the meninges; sticks - diphtheria, dysentery, tuberculosis, typhoid - the causative agents of the corresponding diseases. Pathogenic fungi cause a group of diseases called mycoses. Among the simplest pathogens are malarial Plasmodium, Giardia, Trichomonas, amoeba.

• The vital activity of microorganisms necessary condition the existence of an organic world on Earth. Thanks to the activity of microbes, the mineralization of organic residues is carried out, which ensures a continuous supply of carbon dioxide to the atmosphere, without which photosynthesis by plants is impossible. They take an active part in various geological processes. Weathering rocks, soil formation, the formation of saltpeter, various ores (including sulfuric), limestone, oil, hard coal, peat - all these and many other processes occur with the direct participation of microorganisms.

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Ecology of microorganisms studies the relationship of microorganisms with each other and the environment. Microorganisms are found in soil, water, air, plants, humans and animals, and even in space

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Microorganisms - component biocenosis, i.e. a set of animals, plants and microorganisms inhabiting a biotope - a piece of land or a reservoir with homogeneous living conditions. The community of microorganisms living in certain areas of the environment is called microbiocenosis.

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The spread of microbes in the environment Soil microflora Water microflora Air microflora Food microflora Microflora of plant medicinal raw materials, phytopathogenic microbes Microflora of industrial, household and medical facilities The role of microbes in the circulation of substances in nature

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1. Soil microflora The soil is inhabited by a variety of microorganisms: bacteria, fungi and protozoa. The number of bacteria in the soil reaches 10 billion cells per 1 year. There are relatively few microorganisms on the soil surface, because they are detrimental to UV rays, drying and other factors. The composition of the soil microflora depends on its type, humidity, etc. The soil is a habitat for pathogenic spore-forming rods (causative agents of anthrax, botulism, tetanus, gas gangrene), they are able to persist for a long time, and some even multiply in the soil. There are also fungi in the soil. They participate in the transformation of nitrogen compounds, release biologically active substances, antibiotics and toxins. Toxin-forming fungi, getting into human food, cause intoxication - mycotoxicosis and aflatoxicosis.

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2. Water microflora Various bacteria are found in the waters of fresh water bodies: rod-shaped (pseudomonas), cocci-shaped (micrococci) and convoluted. Water pollution with organic substances is accompanied by an increase in anaerobic and aerobic bacteria, as well as fungi. The microflora of water plays the role of an active factor in the process of its self-purification from organic waste, which is utilized by microorganisms. Together with polluted storm, melt and sewage, representatives of the normal microflora of humans and animals (E. coli, enterococci) and pathogens of intestinal infections (typhoid fever, paratyphoid fever, dysentery, cholera, etc.) enter lakes and rivers. Thus, water is a factor in the transmission of pathogens of many infectious diseases. The water of artesian wells practically does not contain microorganisms.

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3. Air microflora Microorganisms enter the air from the respiratory tract and with drops of human and animal saliva. Coccoid and rod-shaped bacteria, bacilli, clostridia, actinomycetes, fungi and viruses are found here. Sunlight and other factors contribute to the death of air microflora. More microorganisms are present in the air major cities and indoors.

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4. Microflora of food products Food products can be contaminated with various microorganisms. At a low storage temperature of meat and meat products, even in frozen meat, microbes capable of reproduction under psychrophilic conditions (pseudomonas, proteus, etc.) may predominate. Food products contaminated with microorganisms can cause a wide variety of food poisoning and intoxication, as well as infectious diseases such as anthrax, brucellosis, and tuberculosis.

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5. Microflora of herbal medicinal raw materials, phytopathogenic microbes Herbal medicinal raw materials can be contaminated with microorganisms in the process of its production: infection occurs through water, non-sterile pharmacy utensils, the air of industrial premises and the hands of personnel. Insemination also occurs due to the normal microflora of plants and phytopathogenic microorganisms - pathogens of plant diseases. Phytopathogenic microorganisms are able to spread and infect a large number of plants.

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6. The role of microbes in the circulation of substances in nature Organic compounds of plant and animal origin are mineralized by microorganisms to carbon, nitrogen, sulfur, phosphorus, iron and other elements.

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Influence of factors environment on microbes Physical, chemical and biological environmental factors have different effects on microorganisms: bactericidal - leading to cell death; bacteriostatic - overwhelming reproduction of microorganisms; mutagenic - changing the hereditary properties of microbes.

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Effect of Temperature Microorganisms tolerate low temperatures well. They can be stored frozen for a long time, including at a liquid nitrogen temperature of -1730. The temperature factor is taken into account during sterilization. Vegetative forms of bacteria die at t 600 for 20-30 minutes, spores in an autoclave at 1200 under steam pressure.

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desiccation Dehydration causes disruption of the functions of most micro-organisms. The causative agents of gonorrhea, meningitis, cholera, dysentery, and other pathogenic microorganisms are most sensitive to drying. More resistant are bacteria protected by mucus sputum. Thus, tuberculosis bacteria in sputum can withstand drying up to 90 days. Bacterial spores are especially resistant (anthrax spores remain in the soil for centuries). To prolong viability, when preserving microorganisms, lyophilization is used - drying under vacuum from a frozen state. Freeze-dried cultures, o/w, and immunological preparations are stored for a long time (for several years) without changing their original properties.

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Effect of radiation Ionizing radiation is used to sterilize disposable plastic microbiological tableware, nutrient media, dressings, medicines, etc. m / o already h / o a short period of time. UVR is used for air disinfection in MO (bactericidal lamps)

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Influence of chemicals Chem. in-va have a different effect on m / o: they serve as a source of nutrition, do not have any effect, stimulate or inhibit growth, cause death. Antimicrobial chem. in-va are used as antiseptic and disinfectants, tk. have bactericidal, virucidal, fungicidal action, etc.

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Influence biological factors Microorganisms are in various relationships with each other. The coexistence of two different organisms is called symbiosis. There are several options for useful relationships: Metabolism - the relationship of m / o, in which one of them uses for its life the waste products of the other. Mutualism is a mutually beneficial relationship between different organisms. Commensalism - cohabitation of individuals various kinds in which one species benefits from the symbiosis without harming the other. Commensals are bacteria - representatives of the normal human microflora. Satellism is an increase in the growth of one type of m / o under the influence of another type of m / o. For example, colonies of yeast or sarcin, releasing metabolites into the nutrient medium, stimulate the growth of colonies of other m/o around them.

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Sanitary microbiology A branch of medical microbiology that studies m / o contained in the environment and can have an adverse effect on human health. It develops microbiological indicators of hygienic regulation, methods for monitoring the effectiveness of disinfection of environmental objects, and also detects pathogenic, conditionally pathogenic and sanitary-indicative microorganisms in environmental objects.

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Detection of pathogenic m/o allows assessing the epidemiological situation and taking appropriate measures to combat and prevent infectious diseases. Opportunistic m / o can cause purulent-inflammatory processes in a weakened body. In addition, they can get on food, multiply and accumulate in them, causing food poisoning of microbial etiology. Sanitary indicative m/o are used to indirectly determine the possible presence of pathogenic m/o in environmental objects. Their presence indicates contamination of the object with excretions of humans and animals, because. they reside permanently in the same organs as pathogens and share a common route of excretion into the environment.

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1. Sanitary indicative soil bacteria are Escherichia coli, Clostridium perfringens, Streptococcus feacalis, thermophilic bacteria. The presence of the first three is used to judge the degree of fecal contamination of the soil. 2. The health indicator microorganism for water is E. coli (Escherichiae coli). Good-quality drinking water must meet the requirements State standard: Suitable - 1 ml of water contains no more than 100 microorganisms; doubtful - 1 ml of water contains 100 - 450 microorganisms; unsuitable - 1 ml of water contains more than 500 microorganisms. 3. Sanitary-indicative microorganisms for air are Staphylococcus aureus and hemolytic streptococci (Staphylococcus aureus, group Streptococcus viridans and Streptococcus haemolyticus).

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Presentation on the topic: “Bacteria and microorganisms” by Alla Krushelnitskaya Group O - 31 Contents Bacteria. Species Classification of microorganisms Principles of subdivision of bacteria into groups. The structure of a bacterial cell. Bacteria are mostly prokaryotes. These are the simplest, smallest and most widespread organisms. However, having the ability to constantly develop. Bacteria are so different from other living organisms that they are isolated in a separate kingdom. View B modern view species in microbiology - a set of microorganisms that have a common evolutionary origin, a close genotype and the closest possible phenotypic characteristics. When studying, identifying and classifying microorganisms, the following (geno- and phenotypic) characteristics are most often studied: 1. Morphological - form, size, features of relative position, structure. 2. Tinctorial - relation to various dyes (the nature of staining), primarily to Gram stain. On this basis, all microorganisms are divided into gram-positive and gram-negative. 3.Cultural - the nature of the growth of a microorganism on nutrient media. 4. Biochemical - the ability to ferment various substrates (carbohydrates, proteins and amino acids, etc.), to form various biochemical products in the process of life due to the activity of various enzyme systems and metabolic features. 5. Antigenic - depend mainly on the chemical composition and structure of the cell wall, the presence of flagella, capsules, are recognized by the ability of the macroorganism (host) to produce antibodies and other forms of immune response, are detected in immunological reactions. 6. Physiological methods of carbohydrate (autotrophs, heterotrophs), nitrogen (aminoautotrophs, aminoheterotrophs) and other types of nutrition, type of respiration (aerobes, microaerophiles, facultative anaerobes, strict anaerobes). 7.Mobility and types of movement. 8. Ability to spore formation, the nature of the dispute. 9. Sensitivity to bacteriophages, phage typing. 10.Chemical composition of cell walls - basic sugars and amino acids, lipid and fatty acid composition. 11. Protein spectrum (polypeptide profile). 12. Sensitivity to antibiotics and other drugs. 13. Genotypic (use of methods of genosystematics). In microbiology, a number of other terms are often used to characterize microorganisms. Strain - any specific sample (isolate) of a given species. Strains of the same species that differ in antigenic characteristics are called serotypes (serovariants, abbreviated as serovars), according to sensitivity to specific phages - phage types, biochemical properties - chemovars, biological properties - biovars, etc. A colony is a visible isolated structure during the reproduction of bacteria on dense nutrient media, it can develop from one or more parental cells. If the colony developed from one parent cell, then the offspring is called a clone. Culture - the whole set of microorganisms of the same species grown on a dense or liquid nutrient medium. The basic principle of bacteriological work is the isolation and study of the properties of only pure (homogeneous, without the admixture of foreign microflora) cultures. According to the form, the following main groups of microorganisms are distinguished. Globular or cocci. Rod-shaped. Collection. Filiform. Cocciform bacteria (cocci), according to the nature of the mutual arrangement after division, are divided into: 1. Micrococci. Cells are located alone. They are part of the normal microflora, are in the external environment. They do not cause disease in humans. 2. Diplococci. The division of these microorganisms occurs in one plane, pairs of cells are formed. Among diplococci there are many pathogenic microorganisms - gonococcus, meningococcus, pneumococcus. 3. Streptococci. The division is carried out in one plane, the multiplying cells keep the connection (do not diverge), forming chains. Many pathogenic microorganisms are the causative agents of tonsillitis, scarlet fever, purulent inflammatory processes. 4. Tetracocci. Division in two mutually perpendicular planes with the formation of tetrads (i.e., four cells each). They have no medical significance. 5. Sarcins. Division in three mutually perpendicular planes, forming bales (packages) of 8, 16 or more cells. Often found in the air. 6. Staphylococci (from Latin - a bunch of grapes). They divide randomly in different planes, forming clusters resembling bunches of grapes. They cause numerous diseases, primarily pyoinflammatory. rod-shaped microorganisms. 1. Bacteria are rods that do not form spores. 2.Bacilli - aerobic spore-forming microbes. The spore diameter usually does not exceed the size (“width”) of the cell (endospore). 3. Clostridia - anaerobic spore-forming microbes. The diameter of the spore is greater than the diameter (diameter) of the vegetative cell, and therefore the cell resembles a spindle or a tennis racket. Convolute forms of microorganisms. 1. Vibrio and campylobacter - have one bend, can be in the form of a comma, a short curl. 2. Spirilla - have 2-3 curls. 3. Spirochetes - have a different number of curls, axostyle - a collection of fibrils, the nature of movement specific to various representatives and structural features (especially the end sections). Of the large number of spirochetes, representatives of three genera are of greatest medical importance - Borrelia, Treponema, Leptospira. Burgey's classification of microorganisms according to The role of microorganisms in the etiopathogenesis of diseases characterized by the greatest lethality Leading causes of death, 2004 Definitely play a role in pathogenesis Associated with the development of these pathologies * 1. Heart disease Chlamydia pneumoniae, Helicobacter pylori simple virus; Mycobacterium 2. Malignant neoplasms Hepatitis B and C viruses (hepatic cell carcinoma); papillomaviruses (cervical cancer); Epstein-Barr virus (nosopharyngeal carcinoma, lymphomas); herpes virus type 8 and HIV (Kaposi's sarcoma); HTLV (leukemias, lymphomas); H. pylori (stomach and duodenal cancer); Schistosoma haematonium (bladder cancer); Schistosoma japonicum (cancer of the liver and rectum); cytomegalovirus (via immunosuppression) Hepatitis C virus (non-Hodgkin's lymphomas, thyroid cancer); Papillomaviruses (ano-genital cancer and bladder cancer); Herpes virus type 2 (bladder cancer); Salmonella typhi (hepatobiliary cancer); Chlamydia pneumonia (lung cancer); Chlamydia trachomatis (squamous cell carcinoma of the cervix); Chlamydia psittaci and C. jejuni (lymphomas); Mycoplasma sp. (tumors of various localization); Propionibacterium acnes (prostate cancer) herpes, cytomegalovirus, hepatitis C virus, periodontal infections and other tuberculosis, enteroviruses Echo and Coxsackie B, hepatitis A viruses, influenza and mumps, Nanobacterium sanguineum, a number of uncharacterized viruses Schematic representation of various bacteria. 1. 2. 3. 4. 5. 6. Staphylococci Diplococci Streptococci Bacteria Vibrios Spirochetes The structure of a bacterial cell. Mandatory organelles are: nuclear apparatus, cytoplasm, cytoplasmic membrane. 1. In the center of a bacterial cell there is a nucleoid - a nuclear formation, most often represented by one ring-shaped chromosome. Consists of a double-stranded strand of DNA. The nucleoid is not separated from the cytoplasm by a nuclear membrane. 2. Cytoplasm is a complex colloidal system containing various inclusions of metabolic origin (granules of volutin, glycogen, granulosa, etc.), ribosomes and other elements of the protein-synthesizing system, plasmids (extranucleoid DNA), mesosomes (formed as a result of invagination of the cytoplasmic membrane into the cytoplasm, participate in energy metabolism, spore formation, formation of the intercellular septum during division). 3. The cytoplasmic membrane limits the cytoplasm from the outside, has a three-layer structure and performs a number of important functions - barrier (creates and maintains osmotic pressure), energy (contains many enzyme systems - respiratory, redox, carries out electron transfer), transport (transfer of various substances into and out of the cell). 4. Cell wall - inherent in most bacteria (except for mycoplasmas, acholeplasmas and some other microorganisms that do not have a true cell wall). It has a number of functions, first of all, it provides mechanical protection and a permanent shape of cells; antigenic properties of bacteria are largely associated with its presence. It consists of two main layers, of which the outer one is more plastic, the inner one is rigid. The surface structures of bacteria (optional, like the cell wall) include the capsule, flagella, microvilli. A capsule or mucous layer surrounds the shell of a number of bacteria. Allocate a microcapsule, detected by electron microscopy in the form of a layer of microfibrils, and a macrocapsule, detected by light microscopy. The capsule is a protective structure. Flagella. Motile bacteria can be gliding (moving on a solid surface as a result of wave-like contractions) or floating, moving due to filamentous spirally curved protein (flagellin in chemical composition) formations - flagella. According to the location and number of flagella, a number of forms of bacteria are distinguished. A. Monotrichous - have one polar flagellum. V. Lofotrichs - have a polar bundle of flagella. S. Amphitrichous - have flagella at diametrically opposite poles. D. Peritrichous - have flagella around the entire perimeter of the bacterial cell. Fimbria or cilia are short filaments that surround a bacterial cell in large numbers, with the help of which bacteria are attached to substrates (for example, to the surface of mucous membranes). F-drank (fertility factor) - the bacterial conjugation apparatus, found in small quantities in the form of thin protein villi. Under unfavorable conditions, for example, with a lack of water, many bacteria go into a dormant state. The cell loses water, shrinks somewhat, and remains dormant until water reappears. Some species survive periods of drought, heat, or cold in the form of spores. The formation of spores in bacteria is not a way of reproduction, since each cell produces only one spore and the total number of individuals does not increase. Endospores and sporulation. Spore formation is a way of preserving certain types of bacteria in adverse environmental conditions. Endospores are formed in the cytoplasm, they are cells with low metabolic activity and high resistance (resistance) to desiccation, chemical factors, high temperature and other adverse environmental factors. Bacteria form only one spore. Fungi and protozoa have a clearly defined nucleus and belong to eukaryotes. We will consider their structure in more detail in the following sections.

Temperature The most favorable temperature for microorganisms is called optimal. It is located between the extreme temperature levels - the temperature minimum (lowest temperature) and the temperature maximum (highest temperature), at which the development of microorganisms is still possible. Depending on the limits within which the temperature is optimal for microbes, they are all divided into three groups: Psychrophiles; Thermophiles; Mesophiles.

Psychrophiles (cold-loving microorganisms) develop well at relatively low temperatures. For them, the optimum is about 10°C, the minimum is from -10 to 0°C and the maximum is about 30°C. Psychrophiles include certain putrefactive bacteria and molds that cause spoilage of food stored in refrigerators and glaciers. Psychrophilic microorganisms live in the soil of the polar regions and the waters of cold seas. Thermophiles (heat-loving microorganisms) have a temperature optimum of about 50°C, a minimum of about 30°C and a maximum in the range of 70-80°C. Such microorganisms live in hot water sources, self-heating masses of hay, grain, manure, etc.

Mesophiles develop best at about 30°C (optimum). The temperature minimum for these microorganisms is 0-10°C, and the maximum reaches 50°C. Mesophiles represent the most common group of microorganisms. This group includes most bacteria, molds and yeasts. The causative agents of many diseases are also mesophilic.

A decrease in temperature from the optimum point affects microorganisms much weaker than an increase in temperature to a maximum. A temperature drop below the minimum usually does not lead to death of a microbial cell, but slows down or stops its development. The cell passes into a state of anabiosis, i.e., latent life activity, similar to the hibernation of many animal organisms. After the temperature rises to a level close to the optimum, the microorganisms return to normal activity again.

Low temperatures are widely used in storage practice food products. Products are stored refrigerated (from 10 to 2°C) and frozen (from 15 to 30°C). The shelf life of chilled products cannot be long, since the development of microorganisms on them does not stop, but only slows down. Frozen products are stored for a longer time, since the development of microorganisms on them is excluded. However, after thawing, such products can quickly deteriorate due to the intensive reproduction of microorganisms that have retained their viability.

An increase in temperature from the optimum point has a dramatic effect on microorganisms. Heating above the temperature maximum leads to the rapid death of microbes. Most microorganisms die at a temperature of 60-70 ° C in minutes, and when heated to ° C - within a few seconds to 3 minutes. Bacterial spores withstand heating up to 100°C for several hours. To destroy the spores, they resort to heating up to 120 ° for minutes. The reason for the death of microorganisms during heating is mainly the coagulation of the protein substances of the cell and the destruction of enzymes.

Pasteurization is heating the product at a temperature of 63 to 75°C for minutes (long pasteurization) or from 75 to 93°C for a few seconds (short pasteurization). As a result of pasteurization, most of the vegetative microbial cells are destroyed, and the spores remain alive. Therefore, pasteurized foods must be kept refrigerated to prevent spores from germinating. Milk, wine, fruit and vegetable juices and other products are pasteurized. Sterilization means heating the product at 120°C for minutes. During sterilization, which is carried out in special autoclaves, all microorganisms and their spores die. As a result, sterilized products in airtight containers can be stored for years.

Humidity of the environment. It plays an important role in the life of microorganisms. The cells of microorganisms contain up to 85% water. All metabolic processes take place in an aquatic environment, therefore, the development and reproduction of microorganisms is possible only in an environment containing a sufficient amount of moisture. Reducing the humidity of the environment leads first to a slowdown in the reproduction of microbes, and then to its complete cessation. The development of bacteria stops at an environmental humidity of about 25%, and molds - about 15%.

When dried products are moistened, they undergo quick spoilage due to the rapid development of microorganisms that have retained their viability on them. Dried products have the ability to absorb moisture from the surrounding air, so during storage it is necessary to ensure that the relative humidity of the air does not exceed a certain value. Relative humidity is the ratio of the actual amount of moisture in the air to the amount that completely saturates the air at a given temperature, expressed as a percentage. The development of mold fungi on dried products becomes possible if the relative humidity of the air exceeds 75-80%.

The concentration of dissolved substances in the medium. The vital activity of microorganisms takes place in media that are more or less concentrated solutions of substances. Some of the microorganisms live in fresh water, where the concentration of dissolved substances is insignificant and, consequently, the osmotic pressure is low (usually tenths of the atmosphere). Other microbes, on the contrary, live in conditions of high concentrations of substances and significant osmotic pressure, sometimes reaching tens and hundreds of atmospheres. Most microorganisms can exist in media with a relatively low concentration of dissolved substances and are highly sensitive to its fluctuations.

Preservation is based on the destructive effect of high concentrations of substances on microorganisms. food products table salt and sugar. Content in the environment table salt up to 3% slows down the reproduction of many microorganisms. Putrefactive and lactic acid bacteria are especially sensitive to the action of table salt. When the product contains about 10% salt, the vital activity of these bacteria is completely suppressed.

Microorganisms also die in solutions containing 60-70% sugar. Berries, fruits, milk, etc. are preserved with the help of sugar. Some microorganisms, which usually live under conditions of low osmotic pressure, develop relatively well on salted or candied foods. There are also such microbes that are able to develop normally only in conditions of high concentration of sodium chloride (for example, in brine). Such microbes are called halophiles. Often, halophiles cause spoilage of salted food products. The preservative effect of sugar is much weaker than that of table salt, therefore, in the practice of canning with sugar, products are still heated in hermetically sealed containers.

The bactericidal (killing bacteria) effect of sunlight is primarily due to the presence of ultraviolet rays in it. These rays have great chemical and biological activity. They cause the decomposition and synthesis of certain organic compounds, coagulate proteins, destroy enzymes, and have a detrimental effect on the cells of microorganisms, plants and animals. Special devices have been created for the artificial production of ultraviolet rays. With the help of these rays, drinking water, the air of medical and industrial premises, refrigeration chambers, etc. are disinfected. The disadvantage of ultraviolet rays is their low penetrating power, as a result of which they can only be used to irradiate the surface of objects.

2. Influence of chemical factors. Chemical environmental factors largely determine the vital activity of microorganisms. Among the chemical factors highest value have the reaction of the environment and its chemical composition. Environment reaction The degree of acidity or alkalinity of the environment has a strong effect on microorganisms. Acidity and alkalinity are here understood as the concentration of hydrogen and hydroxide ions.

Different microorganisms are adapted to living in environments with different reactions. Some of them develop better in an acidic environment, others - in a neutral or slightly alkaline. For most molds and yeasts, a slightly acidic environment is most favorable. Bacteria need a neutral or slightly alkaline environment. Changing the reaction of the environment to microorganisms has a depressing effect. Increasing the acidity of the environment can cause the death of bacteria, increased acidity is especially detrimental to putrefactive bacteria. Bacterial spores are more resistant to environmental changes than vegetative cells.

Some bacteria in the process of life themselves produce organic acids. Such bacteria (for example, lactic acid) are more enduring than others, however, after accumulation in the environment, they a certain amount acids are gradually destroyed. There are microorganisms that can regulate the reaction of the medium, bringing it to the desired level by releasing substances that acidify or alkalize the medium. Such microorganisms include, for example, yeasts. For them, an acidic environment is normal, in which alcoholic fermentation proceeds. However, if the yeast enters a slightly alkaline or neutral environment, then instead of alcohol, they form acetic acid. After the medium acquires an acidic reaction favorable for the yeast, they begin to produce ethyl alcohol.

Chemical composition of the environment. In the vital activity of microorganisms, the chemical composition of the environment plays an important role, since among the chemicals that form the environment and are necessary for microorganisms, there may be toxic substances. These substances, having penetrated into the cell, combine with the elements of protoplasm, disrupt the metabolism and destroy the cell. Salts of heavy metals (mercury, silver, etc.), ions of heavy metals (silver, copper, zinc, etc.), chlorine, iodine, hydrogen peroxide, potassium permanganate, sulfurous acid and sulfur dioxide, carbon monoxide and carbon dioxide, alcohols, organic acids and other substances. In practice, some of these substances are used to combat microorganisms. Such substances are called antiseptics (anti-putrefactive). Antiseptics have a bactericidal effect of various strengths. The effectiveness of the use of antiseptics also largely depends on their concentration and duration of action, temperature and reaction of the environment.

Antiseptic substances are widely used in medicine and veterinary medicine. With their help, rooms, equipment and tools are disinfected. Disinfection of premises, equipment and tools with the help of antiseptics is called disinfection, and the antiseptic substances used in this case are disinfectants. As disinfectants, carbolic acid (phenol), formalin, sublimate solution, bleach, cresol, sulfur dioxide and others are used. Disinfection with liquid antiseptics is carried out by spraying or wiping, and gaseous - by fumigation.

3. Influence of biological factors. In nature, different representatives of the world of microorganisms live together. Certain relationships are established between them. In some cases, these relationships are mutually beneficial. This mutually beneficial cohabitation is called symbiosis. Symbiosis occurs between different types microorganisms, between microorganisms and plants, between microorganisms and animals. Symbionts, i.e. mutually beneficial cohabiting organisms, are nodule bacteria and legumes. Bacteria receive carbonaceous substances from legumes, and they themselves provide plants with nitrogen compounds.

Among microorganisms, antagonism is widespread, in which one type of microbe suppresses the development of others or causes their death. The phenomenon of antagonism occurs, for example, in the relationship between lactic acid and putrefactive bacteria. Lactic acid bacteria secrete lactic acid, which inhibits putrefactive bacteria. Antagonism between lactic acid and putrefactive bacteria is used in the manufacture of fermented vegetables, fermented milk products, etc.

Often, microbes release special substances into the environment that suppress or have a detrimental effect on other microorganisms. Such substances are called antibiotics (from the Greek: anti - against, bios - life). Antibiotics are secreted by many actinomycetes, bacteria and fungi. Around such antagonist microorganisms, a sterile zone is created on the substrate, free from other microorganisms, since the latter die under the action of antibiotics. The property of microorganisms to secrete antibiotics is widely practical use in medicine. Currently, a large number of antibiotics are known: penicillin, streptomycin, biomycin, terramycin and a number of others.

Soil microflora. Soil is the main source of spread of microorganisms, because in the soil: a lot of nutrients (organic, mineral), a sufficient amount of moisture, which protects against direct sunlight and sudden changes in temperature. Most microbes are found at a depth of 1 to 30 cm. There are fewer of them in sandy soil than in chernozem soil. Soil microorganisms are represented by bacteria, microscopic fungi and yeasts. Microorganisms play an important role in the formation and enrichment of soils and affect their fertility. The greatest number of microbes is found in soils that contain a lot of organic residues (in arable, humus-fertilized and moist soils).

Pathogenic microorganisms are also found in the soil, which enter with the corpses of animals, garbage. They are the causative agents of botulism, tetanus, gas gangrene and other diseases. In order to prevent serious diseases, food industry workers should not allow soil contamination of raw materials, semi-finished products and finished products. Soil is the main reservoir from which microbes enter water and air.

Water microflora. Water is a favorable environment for the life of microorganisms. Water pollution can be up to a million microbes in 1 ml. Microorganisms enter water bodies with various runoff from the soil surface, from the air, etc. The number of microorganisms in water depends on its origin. In open reservoirs (rivers, lakes, ponds) most of all microorganisms; in artesian water - less, because passing through the layers of soil, it lingers. Water is a very dangerous source of the spread of pathogenic microorganisms, especially during epidemics of cholera, typhoid, dysentery and other intestinal infections. They can survive in water for up to several months.

The main source of bacterial contamination of water bodies are wastewater settlements and industrial enterprises, (effluents contain chemicals - ammonia, hydrogen sulfide, nitric acid salts, chlorides, phosphoric acid salts) contaminated with household and industrial waste, as well as rainwater, which carry away a large number of microorganisms from the air and soil surface. drinking water and treated wastewater can be disinfected by chlorination with gaseous chlorine, bleach or other chlorine-containing compounds, ozonation, irradiation with ultraviolet rays. Water is defended, filtered. Water used for technological purposes in bakery and flour production confectionery, must meet the requirements of GOST The total number of bacterial cells is not more than 100 per 1 ml, bacteria of the Escherichia coli group is not more than 3 per 1 liter.

Air microflora. The air is an unfavorable environment for microorganisms, since it does not contain nutrients and its humidity is lower than necessary for their development. Microorganisms enter the air with dust. In the air, they either die or settle again in the form of spores on the surface of the earth and various objects. The content of microorganisms in the air depends on various factors: the higher from the surface of the earth, the less microorganisms in the air. There are almost no microorganisms in the air above the surface of the oceans, seas, over snowy plains, forests and mountain peaks. But more over land. The number of microorganisms in the air depends on the proximity to the settlement. There are more germs in the air of large cities than in small ones. settlements. In the warm season, there are more microorganisms in the air than in the cold. the lower layers of air are more contaminated with microbes (1 m 3 of air contains tens of thousands of microorganisms).

The composition of the air microflora is different. The most common in it are spores of bacteria and fungi, as well as pathogenic microorganisms and viruses. The pathogens of various diseases, respiratory tract infections, influenza, tuberculosis, meningitis, etc., as well as microbes that cause infection of technological raw materials and finished products (flour and bread molding) are transmitted through the air. Air purity in industrial premises achieved through microbiological analysis of air samples. They are cleaned with ventilation, wet cleaning, bactericidal lamps, disinfectants.

Microflora of the human body. On human skin and internal organs microbes are always present. As a result of communication with nature and with people, a person experiences an “exchange” of microflora. Microbes enter the human body with food, water, and air. The microflora of the oral cavity is very diverse. Temperature, humidity, alkaline reaction of saliva, food residues all favor the development of various microorganisms. There are many micrococci, streptococci, staphylococci, vibrios, spirochetes, rods, yeasts, etc. in the mouth. Dental plaque, teeth affected by caries, tonsils are abundantly seeded with microbes.

Daily brushing of teeth at night and in the morning, rinsing the mouth after meals, healthy teeth - all this will save a person from many diseases. The respiratory organs do not have a permanent microflora and are completely dependent on the content of microbes in the inhaled air. The microflora of the gastrointestinal tract is abundant and diverse. E. coli, some cocci constantly live in the intestines. Therefore, all public catering workers are systematically examined for bacteriocarrier.

Human hands are contaminated with microbes from the environment (air, objects). Various microbes dangerous to human health are found on the hands, causing dysentery, typhoid fever, hepatitis, salmonellosis, etc. The presence of Escherichia coli on the hands indicates a low sanitary culture of a person who does not observe sanitary regulations personal hygiene (does not wash hands before eating, before cooking, after using the toilet), about unsatisfactory sanitary and hygienic working and living conditions. Maintaining a normal state of health, clean hands, whole body, oral cavity necessary for all people, especially food service workers.