putrefactive bacteria. putrefactive microorganisms. Facultative anaerobic non-spore rods

The group of putrefactive bacteria includes microorganisms that cause a deep breakdown of proteins. In this case, a number of substances are formed that have an unpleasant odor, taste, and often poisonous properties. Putrefactive bacteria can be either aerobes or anaerobes, spore-bearing or non-spore-bearing.

Facultative aerobic non-spore putrefactive bacteria often found in milk include gram-negative rods Proteus vulgaris (Proteus), which are capable of actively peptonizing milk with gas evolution. With the development of these microorganisms in milk, its acidity first slightly increases (due to the formation of fatty acids), and then decreases as a result of the accumulation of alkaline products. Non-spore-forming bacteria, such as Proteus vulgaris, can be introduced into milk from equipment, water, and other sources. During pasteurization of milk, Proteus vulgaris die.

Aerobic spore bacteria include Bac. subtilis (hay stick), Vas. mesentericus (potato stick), Vas. mycoides, Vas. megatherium, etc. All of them are mobile, positively Gram-stained, develop rapidly in milk, actively decomposing proteins. At the same time, milk first coagulates without a significant increase in acidity, then peptonization of milk occurs from the surface of the clot. In some spore sticks (for example, hay), milk peptonization begins without preliminary coagulation of casein. Of the anaerobic spore putrefactive bacteria, you are found in milk. putrificus and you. polymyxa.

You. putrificus - a mobile rod that decomposes proteins with abundant formation of gases (ammonia, carbon dioxide, hydrogen, hydrogen sulfide), you. polymyxa is a mobile rod that forms gas, acids (acetic, formic), ethyl and butyl alcohols and other products in milk.

High sensitivity to a decrease in the reaction of the medium is characteristic of all putrefactive bacteria. This feature determines the extremely limited opportunities for the development of this group of bacteria in the production of fermented milk products. Obviously, in all cases when the lactic acid process develops actively, the vital activity of putrefactive bacteria ceases. In the production of fermented milk products, the development of putrefactive bacteria is possible only in exceptional cases (as a result of the development of a bacteriophage, the lactic acid process is completely or to a large extent stopped, the activity of the starter is lost, etc.). Spores of many putrefactive bacteria can be found in pasteurized milk. However, they practically do not play a role in the production and storage of this product. This is due to the fact that the main residual microflora after pasteurization is lactic acid bacteria, they also seed milk during bottling, therefore, against the background of development (albeit weak, due to low temperatures

storage) of the lactic acid process, the possibility of reproduction of spore microorganisms in pasteurized milk is negligible. In the production and storage of sterilized milk, spore bacteria play an important role. Even minor violations of the sterilization regimes can lead to the entry of spores into sterilized milk and subsequently cause spoilage during storage.

YEAST

The classification of yeasts is based on differences in the nature of their vegetative reproduction (division, budding). sporulation, as well as morphological and physiological features.

According to the ability to sporulate, yeasts are divided into spore-forming and non-spore-forming. Yeasts of the genera Saccharomyces, Zygosaccharomyces, Fabospora and Debaromyces are found in fermented milk products from the spore-forming ones, and from the non-spore-forming ones - the genera Torulopsis and Candida. S. A.

Korolev (1932) divided the yeast found in dairy products into three groups according to their biochemical properties.

First group- yeast that is not capable of alcoholic fermentation, although it consumes some carbohydrates by direct oxidation; these include Mycoderma spp., the colored non-spore yeast Tornla.

Second group- yeast that does not ferment lactose, but ferments other sugars; can develop only in a joint culture with microorganisms that have the enzyme lactase, hydrolyzing milk sugar into monosaccharides; these include certain species of yeast of the genus Saccharomyces. As studies by V.I. Kudryavtsev (1954) and A.M. Skorodumova (1969), in fermented milk products prepared with natural starters, the main representatives of this genus are yeast of the species Sacch. cartilaginosus fermenting maltose and galactose. According to V. I. Kudryavtsev, the yeast of this group can positively influence the taste and aroma of fermented milk products, however, with their excessive development, a defect occurs - swelling. They belong to the so-called wild yeast and are not used in the production of fermented milk products. However, it is possible that productively valuable cultures can be found among the yeasts of this group.

The third group - yeast fermenting lactose. Studies by A. M. Skorodumova (1969) showed that among yeasts isolated from fermented milk products (prepared with natural sourdough), the number of yeasts that independently ferment lactose is relatively small - out of 150 strains - 32 (21%). The largest percentage of yeast fermenting lactose was isolated from kefir fungi and sourdough (34.1%). Yeast fermenting lactose was identified by A. M. Skorodumova as Fabospora fragilis, Saccharomyces lactis, less often Zygosaccharomyces lactis. The ability to ferment lactose is also possessed by some species of Candida and Torulopsis - Candida pseudotropicalis var. lactosa, Torulopsis kefir, Torylopsis sphaerica isolated from kefir fungus (V. I. Bukanova, 1955).

Research conducted in Japan by T. Nakanishi and J. Arai (1968, 1969) also showed that the most common types of lactose-fermenting yeast isolated from raw milk are Saccharomyces lactis, Torulopsis versatilis, Torulopsis sphaerica, Candida pseudotropicalis.

To establish the ratio of yeast to sugars, cultures are sown in parallel in milk-peptone whey containing only lactose and in wort containing maltose. After holding at the optimum temperature, the presence or absence of gas is noted.

The optimum temperature for the development of yeast is 25-30°C, which should be taken into account when choosing the temperature for the maturation of products whose microflora includes them. According to V. II. Bukanova (1955) the main factor regulating the development of different types of yeast in kefir is temperature. Thus, an elevated temperature (30-32 ° C) stimulates the development of Torulopsis sphaerica and yeast that does not ferment lactose. Yeast fermenting lactose develops quite well at 18-20 ° C, however, an increase in temperature to 25 and 30 ° C, as a rule, stimulates their reproduction.

Most yeasts prefer an acidic environment for their development. Therefore, in fermented milk products, the conditions are favorable for them.

Yeast is very widespread in fermented milk products and can be found in almost any sample of a product prepared with natural sourdough. However, yeast develops much more slowly than lactic acid bacteria, so they are found in fermented milk products in smaller numbers than lactic acid bacteria.

The role of yeast and the production of fermented milk products is exceptionally great. Usually yeasts are considered mainly as causative agents of alcoholic fermentation. But this function, apparently, is not the main one. Yeast activates the development of lactic acid bacteria, fortifies products (S. Askalonov, 1957). Yeast fermenting lactose and other sugars are capable of producing antibiotic substances that are active against tubercle bacillus and other microorganisms (A. M. Skorodumova, 1951, 1954; V. I. Bukanova, 1955).

The intensive development of non-starter yeast often leads to swelling and a change in the taste of products such as sour cream, cottage cheese and sweet curd products. Excessive development of yeast contained in kefir starter in violation of technological regimes can also cause gas formation in kefir (“eyes”) and even its swelling.

With the development of bacteria in water, putrefactive, earthy, musty, aromatic (pleasant and unpleasant) sour, similar to the smell of gasoline, alcohol, ammonia and other odors are observed.[ ...]

Beyerink's medium for putrefactive bacteria that form hydrogen sulfide.[ ...]

Bacteria contained in groundwater perform a great deal of geochemical work, modifying the chemical and gas composition of the waters. It should be emphasized that many bacteria that develop in groundwater are harmless to human health and even participate in bacterial purification of water from pollution.[ ...]

Mucous bacteriosis. Pathogens - putrefactive bacteria of the genus Erwinia, mainly E. carotovora (Jones) Holland and its various forms - E. carotovora var. carotovora (Jones) Dye, E. carotovora var. atroseptica (van Hall) Dye, E. carotovora var. carotovora (Jones) Dye, biotype aroideae (Towns) Holland.[ ...]

It is extremely important to know and take into account that bacteria retain their viability during anaerobic (putrefactive) processes for a very long time. During the aerobic process, during the oxidation of organic substances, a significant part of pathogenic bacteria die due to a decrease in the nutrient medium necessary for them.[ ...]

Acidic environment (pH [ ...]

In practice, it has been noted that the total number of bacteria is significantly reduced in the process of settling water. The more polluted the water, the more pathogenic microbes die faster in it. This paradoxical phenomenon is explained by the antagonism of microbes. A decrease in the number of microbes is observed during settling during the first two days: and then algae grow in the settling tanks, which, when they die, are decomposed by putrefactive microorganisms. As a result, the organoleptic properties of water deteriorate, dissolved oxygen disappears, and the oxidizing potential decreases.[ ...]

Hydrochloric acid can inhibit the development of putrefactive and butyric acid bacteria in feed. Since the most accessible source of nitrogen for microorganisms is ammonia, there is a rapid accumulation of hydrochloric acid in canned feed. When the pH value of the medium is below 3.9-4.0, biodegradation processes almost completely stop, and the effect of feed preservation can be quickly achieved. The role of hydrochloric acid is not limited to the suppression of biological processes occurring in feed. It catalyzes the hydrolysis of organic products, including cellulose. This made it possible to significantly improve the quality of silage and the productivity of cattle.[ ...]

Bacteriosis of garlic (Fig. 76). It is caused by several types of bacteria, the most important of which are Erwinia caroto-vora (Jones) Holland and Pseudomonas xanthochlora (Schuster) Slapp. During storage, deep brown sores or cavities appear on the cloves of garlic, extending from the buttock upwards. The tissues of the affected tooth become mother-of-pearl-yellow in color, become as if frozen. Garlic has a typical putrid smell.[ ...]

Proteases - splitting the protein molecule, these enzymes are secreted by many putrefactive bacteria.[ ...]

Relationships of a symbiotic nature are also manifested between some forms of lactic acid bacteria, yeasts and putrefactive bacteria (in the production of kefir).[ ...]

Chemical elements and compounds contained in the atmosphere absorb some of the compounds of sulfur, nitrogen, carbon. Putrefactive bacteria contained in the soil decompose organic residues, returning CO2 to the atmosphere. On fig. 5.2 shows a scheme of environmental pollution with carcinogenic polycyclic aromatic hydrocarbons contained in emissions from vehicles, transport infrastructure facilities, and its purification from these substances in environmental components.[ ...]

During fermentation, a partial precipitation of flakes of protein substances occurs. However, the acidic reaction and the presence of lactic acid bacteria prevent the development of putrefactive bacteria, which contribute to the further process of decomposition of substances. Only after the acids formed have been neutralized can the wastewater be subjected to the process of putrefaction. To save the heat of wastewater, it is necessary to provide a heated room.[ ...]

Purpose of disinfection. The introduction of a disinfectant into water completely ensures the absence of putrefactive and pathogenic bacteria in drinking water in accordance with official standards and studies on Escherichia coli, fecal streptococci and sulfite-reducing Clostridium.[ ...]

In practice, the "biochemical decomposition of proteins" is of great importance. The process of decomposition of proteins or their derivatives under the influence of putrefactive bacteria is called decay. The processes of decay can occur aerobically and anaerobically. Decay is accompanied by the release of pungent substances: ammonia, hydrogen sulfide, skatole, indole, mercaptans, etc. [...]

After mowing, the reservoir must be refilled with water and monitored for some time in order to identify the moment of cessation of putrefactive processes (determination of oxygen, carbon dioxide, oxidizability, ammonia, nitrates, accounting for the number of saprophyte bacteria). The experiment can be started only after the return of hydrochemical and microbiological parameters to normal.[ ...]

The tanning industry requires soft water, as salts that cause hardness impair the use of tannins. Putrefactive bacteria and fungi reduce the strength of the skin, so their presence in the water used for leather production is unacceptable.[ ...]

Detritophages, or saprophages, are organisms that feed on dead organic matter - the remains of plants and animals. These are various putrefactive bacteria, fungi, worms, insect larvae, coprophagous beetles and other animals - they all perform the function of cleansing ecosystems. Detritophages are involved in the formation of soil, peat, bottom sediments of water bodies.[ ...]

Cyanoethylated cotton has high rot and mildew resistance. When kept for a very long time in soil contaminated with bacteria that cause cellulose decay, this product retains its full strength (and in some cases even some increase was observed). Cyan-ethyl-proven cotton and manila hemp also do not rot, being in water for a long time. Rot resistance increases with increasing nitrogen content and becomes absolute when it reaches 2.8-3.5%. However, the presence of even small amounts of carboxyl groups (formed as a result of saponification of cyanoethyl groups) adversely affects the resistance of cellulosic materials to the action of putrefactive bacteria. Therefore, it is very important to carry out cyanoethylation under the mildest conditions. Alkaline treatments should also be reduced or avoided altogether when washing, bleaching and dyeing cyanoethylated cotton.[ ...]

Typical lactic acid fermentation is widely used for the manufacture of lactic acid products in dairies. Lactic acid bacteria are of great importance in the conservation of fresh feed by ensiling. Preservation of juicy feed mass is based on the fermentation of sugars contained in vegetable juice with the formation of lactic acid. Due to the acid reaction of the medium, the development of putrefactive processes in the ensiled mass is prevented. In recent years, silage starters from lactic acid bacteria have been developed. The use of these starter cultures makes it possible to speed up and improve the process of maturation of silage, to avoid the formation of butyric acid.[ ...]

Soft water is essential for tanning! since hardness salts worsen the use of tannins. The water should be free of putrefactive bacteria and fungi that reduce the strength of the skin.[ ...]

Everyone knows the substrate specificity of microorganisms in relation to natural sources of nutrition. So, for example, the decomposition of protein substances is carried out by putrefactive bacteria, which, however, are not able to compete with yeast in the assimilation of carbohydrates. Many microbes are characterized by a special adherence to a particular substrate, and some of them have even received appropriate names, such as cellulose-decomposing bacteria. This property of microorganisms has long been used in practice. Even the same organic matter is attacked by different groups of microorganisms in different ways. This has been shown particularly clearly in connection with the microbial transformation of steroids. GK Skryabin and his co-workers give many examples of high chemical specialization of microorganisms and even use this property as a taxonomic feature. Using the example of cardiac glycosides, we have noted that fungi of the genus Aspergillus introduce a hydroxyl group mainly into the 7p-position of the steroid nucleus, while fusarians prefer to oxidize the 12ß-ynnepoflHbifl atom. A similar phenomenon is observed during microbial degradation of synthetic organic substances. It has been established that the treatment of such a heterogeneous population as soil or activated sludge, for example, with nitro- and dinitrophenols leads to a noticeable enrichment in its species of Achromobacter, Alcaligenes and Flavobacterium, while the addition of thioglycolane increases the relative content of Aeromonas and Vibrio. It is quite obvious that for the successful destruction of certain synthetic organic substances, it is necessary to select the appropriate microorganisms.[ ...]

Waste water without access to air begins to ferment in those cases when it contains predominantly easily decomposable carbohydrates free of nitrogen. Fermentation is caused by bacteria. In this case, along with carbon dioxide, organic acids are formed, which lower the pH to 3-2. This interferes with the work of putrefactive bacteria even in the presence of nitrogen-containing compounds (proteins).[ ...]

If there is waterproof soil at the base of the landfill, the landfill pollutes the groundwater and the surrounding area with the liquid released from it, which contains the decay products of the organic matter of the garbage. The average values of wastewater pollution from the landfill in terms of the total number of bacteria are similar to the average values for urban sewage wastewater, and according to the coli index they even exceed them by 2-3 times.[ ...]

Two-tier settling tanks are usually used for small and medium-sized treatment plants with a capacity of up to 10 thousand m3 / day. The sediment that has fallen into the sludge chamber is fermented under the influence of putrefactive anaerobic bacteria, which break down complex organic substances (fats, proteins, carbohydrates) initially into fatty acids, and later break them down to final, simpler products: methane gases, carbon dioxide and partly hydrogen sulfide. Hydrogen sulfide, during alkaline birth, binds in solution with iron, forming iron sulfide, which stains the precipitate black.[ ...]

When determining sanitary-indicative clostridia, special attention should be paid to the incubation temperature. In summer, at 37 ° C, on the Wilson-Blair medium, up to 90-99% of black colonies grow, formed by putrefactive anaerobic rods and cocci, which are not indicators of fecal pollution of water bodies (T. 3. Artemova, 1973). The joint accounting of these saprophytic bacteria with clostridia significantly distorts the results, the indicator loses its indicator value when assessing the quality of water in reservoirs and drinking water. It is quite possible that the negative attitude towards clostridia as sanitary indicative organisms was supported by the data of inaccurate research methods.[ ...]

Stabilization is carried out in order to prevent decay of sediments to facilitate their burial or disposal. The essence of sediment stabilization is to change their physico-chemical characteristics, under which the vital activity of putrefactive bacteria is suppressed.[ ...]

The oxygen content in water is affected by its pollution with organic substances, the oxidation of which consumes a significant amount of oxygen, as a result of which its concentration decreases. The mucus secreted by some fish into the water serves as a good substrate for putrefactive bacteria, most of which consume oxygen, thereby reducing its content in the water, which is especially dangerous at high stocking densities, and even more so in summer, with the mass development of putrefactive bacteria. Therefore, during summer transportation, it is recommended to change the water in the transport container at least once a day and maintain a lower water temperature, which will slow down the development of putrefactive bacteria. During the autumn-winter transportation of live fish, a daily change of water is not necessary.[ ...]

The decay of the main organic components of the sediment - protein, fats, carbohydrates - occurs with varying intensity, depending on the predominant form of certain microorganisms. So, for example, septic tanks are characterized by an environment that creates conditions for the development of anaerobic putrefactive bacteria of the first stage (phase) of decomposition of organic substances.[ ...]

The vital activity of microorganisms creates interference in the operation of treatment facilities, which consist in the appearance of tastes and odors near the water. The chemical composition of the compounds that cause the appearance of odor depends on the type of microorganism, the conditions of its vital activity. So, actinomycetes in conditions of difficult aeration give the water an earthy smell. The smell of water can also be caused by the massive development of bacteria. Depending on the metabolites formed, odors can also be different: aromatic, hydrogen sulfide, moldy, putrid. During the period of mass development of microorganisms producing odors and flavors, fish meat also acquires an aftertaste. The main role in the occurrence of water odors belongs to amines, organic acids, phenols, ethers, aldehydes, ketones. To remove odors and tastes caused by microorganisms, it is necessary to use additional methods of water purification.[ ...]

Phosphorus is the most important biogenic element, most often limiting the development of the productivity of water bodies. Therefore, the supply of excess phosphorus compounds from the watershed leads to a sharp uncontrolled increase in the plant biomass of the water body (this is especially typical for stagnant and low-flowing water bodies). Eutrophication of the water body occurs, accompanied by a restructuring of the entire aquatic community and leading to the predominance of putrefactive processes (and, accordingly, an increase in turbidity, bacterial concentration, a decrease in the concentration of dissolved oxygen, etc.).[ ...]

Depending on the flow of wastewater, the technological scheme for their purification and sludge treatment, the hydraulic size of suspended solids, various types of sand traps are used: horizontal (with rectilinear and circular movements of water, with various methods of removing sand-pulp), tangential, aerated, less often vertical. In sand traps, 0.02-0.03 l / day is deposited. mineral substances per 1 inhabitant with ash content of 60-95% and humidity of 30-50%. With an ash content of less than 80%, there are fat and oil residues on the sand, which can become a medium for putrefactive bacteria, for the development of fly larvae, which leads to environmental pollution. To avoid this, it is recommended to recycle the sand pulp or aerate it (similar to an aerated sand trap). Sand traps release up to 95% of mineral particles from wastewater.[ ...]

Blue-green algae develop most intensively in stagnant reservoirs with warm water. Their development has reached a particularly large scale in reservoirs belonging to the lacustrine type with water exchange 2 ... 4 times a year. At the same time, their decay products become a source of water pollution. As a result of the screening effect of flowering spots (shading), photosynthesis processes in the water column are suppressed, which is accompanied by the death of food organisms and the death of fish. At the same time, mainly juvenile perch fish (perch, perch, ruff) perish.[ ...]

At the beginning of our century, a microbiological theory of aging arose, the creator of which was I. I. Mechnikov, who distinguished between physiological and pathological old age. He believed that human old age is pathological, that is, premature. The basis of the ideas of I. I. Mechnikov was the doctrine of orthobiosis (Orthos - correct, bios - life), according to which the main cause of aging is damage to nerve cells by intoxication products resulting from putrefaction in the large intestine. Developing the doctrine of a normal lifestyle (observance of hygiene rules, regular work, abstinence from bad habits), I. I. Mechnikov also proposed a way to suppress putrefactive intestinal bacteria by consuming fermented milk products.[ ...]

A comparative evaluation of the unified method, which uses Wilson-Blair iron-sulfite medium without antibiotics and an incubation temperature of 37°C, and our modification using an elective modified SPI medium and an incubation temperature of 44-45°C, was carried out. After counting the black colonies that grew in both cases, each of them was identified by reaction to litmus milk, by sporulation and cell morphology. A comparative assessment of the methods was carried out in the study of the water of the reservoir in the process of self-purification and at the stages of purification of drinking water according to the seasons of the year. In winter, no significant difference between the clostridia indices determined by the studied methods was obtained. In summer, black colonies growing at 37°C are 90-99% of putrefactive anaerobic rods and sulfite-reducing cocci, which are not direct indicators of faecal contamination. The joint accounting of these saprophytic bacteria with clostridia significantly distorts the results, as a result of which this group loses its sanitary and indicative value.[ ...]

The performance of septic tanks depends not so much on their shape (round or rectangular), but on some details of their design. Water inlets and outlets should be as far apart as possible to avoid hydraulic short circuits. To a certain extent, this goal is served by the division of large septic tanks into separate chambers. With proper organization of the flow, it is possible to exclude the formation of stagnant zones that are weakly involved in the process of water exchange. The septic tank is calculated in depth in such a way that between the bottom sediment and the layer of floating sludge there is a layer of water about 1 m thick. In this space, the necessary movements of the fermented contents of the septic tank occur, due to which the newly incoming sewage can be well infected with putrefactive bacteria. From here, the minimum useful height is assumed to be 1.2 m. If the filling of the septic tank is planned to a height of more than 2 m, a vertical flow deviation should be provided. Settled and floating sludge should not flow out with water through the holes in the walls of the chambers and through the drain from the septic tank. These requirements for inlet and outlet, as well as for communication between chambers, can be achieved in a variety of ways, so it is difficult to recommend any specific design here.[ ...]

Plastering the walls, even with the use of plaster with a high content of cement, cannot be recommended, as it does not provide water tightness. When aggressive sewage penetrates into the plaster, the latter quickly collapses, and then unprotected sections of the walls are exposed to aggressive action. Therefore, it is more expedient to cover the walls of the septic tank with bituminous emulsions. These emulsions should be applied to a perfectly dry concrete or mortar surface. For effective sealing of the surface, it is necessary to provide a multi-layer coating; the first layer is made of a cold-applied bituminous slurry, on top of which a layer of hot bitumen is then applied. The device of tar coatings is impractical, since some components of the tar, getting into the solution, can cause the death of putrefactive bacteria.

Putrefactive bacteria cause the breakdown of proteins. Depending on the depth of decomposition and the resulting end products, various food defects can occur. These microorganisms are widely distributed in nature. They are found in soil, water, air, food, and in the intestines of humans and animals. Putrefactive microorganisms include aerobic spore and non-spore rods, spore-forming anaerobes, facultative anaerobic non-spore rods. They are the main causative agents of spoilage of dairy products, cause the breakdown of proteins (proteolysis), as a result of which various defects in food products may occur, depending on the depth of protein breakdown. The putrefactive antagonists are lactic acid bacteria, so the putrefactive process of product decay occurs where there is no fermented milk process.

Proteolysis (proteolytic properties) is studied by inoculation of microorganisms in milk, milk agar, meat-peptone gelatin (MBG) and in clotted blood serum. Coagulated milk protein (casein) under the influence of proteolytic enzymes can coagulate with the separation of whey (peptonization) or dissolve (proteolysis). On milk agar around the colonies of proteolytic microorganisms, wide zones of milk clarification are formed. In NRM, inoculation is done by injection into the column of the medium. Crops are grown for 5-7 days at room temperature. Microbes with proteolytic properties liquefy gelatin. Microorganisms that do not have a proteolytic ability grow in the NMF without its liquefaction. In crops on clotted blood serum, proteolytic microorganisms also cause liquefaction, and microbes that do not have this property do not change its consistency.

When studying the proteolytic properties, the ability of microorganisms to form indole, hydrogen sulfide, and ammonia is also determined, that is, to break down proteins to final gaseous products. Putrefactive bacteria are very widespread. They are found in soil, water, air, human and animal intestines, and on food products. These microorganisms include spore-forming aerobic and anaerobic rods, pigment-forming and facultative anaerobic bacteria without spores.

Aerobic non-spore rods

The following bacteria of this group have the greatest impact on the quality of food products: Bacterium prodigiosum, Pseudomonas fluorescens, Pseudomonas pyoceanea (aeruginosa).

Bacterium prodigiosum- a very small stick (1X 0.5 microns), mobile, does not form spores and capsules. Strictly aerobic, small, round, bright red, shiny, juicy colonies grow on MPA. Low temperatures are most favorable for pigment formation. The pigment is insoluble in water, but soluble in chloroform, alcohol, ether, benzene. When growing in liquid media, it also forms a red pigment. Develops at pH 6.5. The optimum development temperature is 25°C (it can grow at 20°C). Liquefies gelatin in layers, coagulates and peptonizes milk; forms ammonia, sometimes hydrogen sulfide and indole; does not ferment glucose and lactose.

Pseudomonas fluorescens- a small thin stick measuring 1-2 X 0.6 microns, mobile, does not form spores and capsules, gram-negative. Strictly aerobic, but there are varieties that can develop with a lack of oxygen. On MPA and other dense nutrient media, juicy, shiny colonies grow, tending to merge and form a greenish-yellow pigment, soluble in water; in liquid media they also form a pigment. The MPB becomes cloudy, sometimes a film appears. Sensitive to acid reaction of the environment. The optimum development temperature is 25°C, but it can also develop at 5-8°C. It is characterized by high enzymatic activity: it dilutes gelatin and blood serum, coagulates and peptonizes milk, litmus milk turns blue. Forms hydrogen sulfide and ammonia, does not form indole; most of them are able to break down fiber and starch. Many strains of Pseudomonas fluorescens produce the enzymes lipase and lecithinase; give positive reactions to catalase, cytochrome oxidase, oxidase. Pseudomonas fluorescens are strong ammonifiers. Glucose and lactose are not fermented.

Pseudomonas pyoceanea. Small stick (2- 3 X 0.6 µm), motile, does not form spores or capsules, Gram-negative. Aerobe, on MPA gives vague, opaque, greenish-blue or turquoise-blue colored colonies due to the formation of pigments soluble in chloroform. Sews in the turbidity of the MPB (sometimes the appearance of a film) and the formation of pigments (yellow - fluorescein and blue - pyocyanin). Like all putrefactive bacteria, it is sensitive to the acidic reaction of the environment. The optimum development temperature is 37°C. Quickly liquefies gelatin and coagulated blood serum, coagulates and peptonizes milk; litmus turns blue, forms ammonia and hydrogen sulfide, does not form indole Possesses lipolytic ability; gives positive reactions to catalase, oxidase, cygochrome oxidase (these properties are inherent in representatives of the genus Pseudomonas). Some strains break down starch and fiber. Does not ferment lactose and sucrose.

Spore-forming anaerobes

Clostridium putrificus, Clostridium sporogenes, Closntridium perfringens most often cause food spoilage.

Clostridium putrificus. A long stick (7 - 9 X 0.4 - 0.7 microns), mobile (sometimes forms chains), forms spherical spores, the size of which exceeds the diameter of the vegetative form. The heat resistance of spores is quite high; does not form capsules; Gram stain positive. Anaerobe, colonies on agar look like a ball of hair, opaque, viscous; causes confusion. MPB. Proteolytic properties are pronounced. Liquefies gelatin and blood serum, milk coagulates and peptonizes, forms hydrogen sulfide, ammonia, indole, causes blackening of the brain environment, forms a hemolysis zone on blood agar, has lipolytic properties; does not have saccharolytic properties.

Clostridium sporogenes. A large rod with rounded ends, 3 - 7 X 0.6 - 0.9 microns in size, is located in separate cells and in the form of chains, mobile, very quickly forms spores. Spores of Clostridium sporogenes remain viable after 30 minutes of heating in a water bath, as well as after 20 minutes of autoclaving at 120°C. Does not form capsules. It stains positively according to Gram, Anaerobe, colonies on agar are small, transparent, later becoming opaque. Clostridium sporogenes has very strong proteolytic properties, causing the putrefaction of proteins with the formation of gases. Liquefies gelatin and blood serum; causes peptonization of milk and blackening of the brain environment; forms hydrogen sulfide; decomposes with the formation of acid and gas galactose, maltose, dextrin, levulose, glycerin, mannitol, sorbitol. The optimum growth temperature is 37°C, but can grow at 50°C.

Facultative anaerobic non-spore rods

Facultative anaerobic non-sporing rods include Proteus vulgaris and Escherichia coli. In 1885, Escherich discovered a microorganism, which was named Escherichia coli (E. coli). This microorganism is a permanent inhabitant of the large intestine of humans and animals. In addition to E. coli, the group of intestinal bacteria includes epiphytic and phytopathogenic species, as well as species whose ecology (origin) has not yet been established. Morphology - these are short (length 1-3 microns, width 0.5-0.8 microns) polymorphic mobile and immobile gram-negative rods that do not form spores.

cultural properties. Bacteria grow well on simple nutrient media: meat-peptone broth (MPB), meat-peptone agar (MPA). On the MPB they give abundant growth with significant turbidity of the medium; the sediment is small, grayish in color, easily broken. They form a parietal ring, the film on the surface of the broth is usually absent. On MPA, the colonies are transparent with a grayish-blue tint, easily merging with each other. On Endo's medium, flat red colonies of medium size form. Red colonies can be with a dark metallic sheen (E. coli) or without shine (E. aerogenes). Colorless colonies are characteristic of lactose-negative variants of E. coli (B. paracoli). They are characterized by wide adaptive variability, as a result of which various variants arise, which complicates their classification.

biochemical properties. Most bacteria do not liquefy gelatin, coagulate milk, break down peptones with the formation of amines, ammonia, hydrogen sulfide, and have high enzymatic activity with respect to lactose, glucose and other sugars, as well as alcohols. They have oxidase activity. According to the ability to break down lactose at a temperature of 37 ° C, CGBs are divided into lactose-negative and lactose-positive Escherichia coli (LCE), or coliforms, which are normalized according to international standards. From the LKP group, fecal Escherichia coli (FEC) stand out, capable of fermenting lactose at a temperature of 44.5 ° C. These include E. coli, not growing on a citrate medium.

Sustainability. The bacteria of the Escherichia coli groups are neutralized by conventional pasteurization methods (65 - 75 °C). At 60 C, Escherichia coli dies after 15 minutes. A 1% solution of phenol causes the death of the microbe after 5-15 minutes, sublimate at a dilution of 1: 1000 - after 2 minutes, resistant to the action of many aniline dyes.

Aerobic spore rods

Putrefactive aerobic spore bacilli Bacillus cereus, Bacillus mycoides, Bacillus mesentericus, Bacillus megatherium, Bacillus subtilis most often cause food defects. Bacillus cereus is a rod 8-9 microns long, 0.9-1.5 microns wide, mobile, forms spores. Gram positive. Individual strains of this microbe can form a capsule.

Bacillus cereus

cultural properties. Bacillus cereus is an aerobe, but can also develop with a lack of oxygen in the air. Large, flattened, grayish-whitish colonies with jagged edges grow on MPA; some strains form a pinkish-brown pigment; on blood agar, colonies with wide, sharply defined hemolysis zones; on MPB-forms a delicate film, parietal ring, uniform turbidity and flocculent sediment at the bottom of the tube. All strains of Bacillus cereus grow rapidly at pH 9 to 9.5; at pH 4.5-5 they stop their development. The optimal development temperature is 30-32 C, the maximum is 37-48C, the minimum is 10C.

enzymatic properties. Bacillus cereus coagulates and peptonizes milk, causes rapid liquefaction of gelatin, is able to form acetylmethylcarbinol, utilize citrate salts, ferment maltose, sucrose. Some strains are able to break down lactose, galactose, dulcitol, inulin, arabinose, glycerin. Manit does not break down any strain.

Sustainability. Bacillus cereus is a spore-forming microbe, therefore it has a significant resistance to heat, drying, high concentrations of salt and sugar. So, Bacillus cereus is often found in pasteurized milk (65-93C), in canned food. It gets into the meat during the slaughter of livestock and butchering carcasses. The cereus stick develops especially actively in crushed products (cutlets, minced meat, sausage), as well as in creams. The microbe can develop at a concentration of table salt in the substrate up to 10-15%, and sugar up to 30-60%. The acidic environment affects it unfavorably. This microorganism is most sensitive to acetic acid.

Pathogenicity. White mice die when large doses of cereus sticks are injected. Unlike the causative agent of anthrax Bacillus anthracis, the cereus bacillus is not pathogenic for guinea pigs and rabbits. It can cause mastitis in cows. Some varieties of this microorganism secrete the enzyme lecithinase (virulence factor).

Diagnostics. Considering the quantitative factor in the pathogenesis of food poisoning caused by Bacillus cereus, smear microscopy (Gram stain) is performed at the first stage of the microbiological study. The presence of Gram-positive rods with a thickness of 0.9 µm in the smears makes it possible to make an approximate diagnosis: "spore aerobe of group Ia". According to the modern classification, group Ia includes Bacillus anthracis and Bacillus cereus. When clarifying the etiology of food poisoning, the differentiation of Bacillus cereus and Bacillus anthracis is of great importance, since the intestinal form of anthrax caused by Bacillus anthracis can be mistaken for food poisoning by clinical signs. The second stage of microbiological research is carried out if the number of rods detected during microscopy reaches 10 in 1 g of the product.

Then, according to the results of microscopy, the pathological material is sown on blood agar in Petri dishes and incubated at 37C for 1 day. The presence of a wide, sharply defined zone of hemolysis allows a preliminary diagnosis of the presence of Bacillus cereus. For final identification, grown colonies are inoculated into Coser's medium and carbohydrate medium with mannitol. They put a sample on lecithinase, acetylmethylcarbinol and differentiate Bacillus anthracis and other representatives of the genus Bacillus Bacillus anthracis differs from Bacillus cereus in a number of characteristic features: growth in broth and gelatin, the ability to form a capsule in the body and on media containing blood or blood serum.

In addition to the methods described above, express methods for differentiating Bacillus anthracis from Bacillus cereus, Bacillus anthracoides, etc. are used: the “necklace” phenomenon, a test with anthrax bacteriophage, a precipitation reaction, and fluorescent microscopy is performed. You can also use the cytopathogenic effect of the Bacillus cereus filtrate on tissue culture cells (the Bacillus anthracis filtrate does not have such an effect). Bacillus cereus differs from other saprophytic spore aerobes in a number of properties: the ability to form lecithinase, acetylmethylcarbinol, the utilization of citrate salts, mannitol fermentation, and growth under anaerobic conditions on a medium with glucose. Lecithinase is of particular importance. The formation of hemolysis zones on blood agar is not a constant feature in Bacillus cereus, since some strains and varieties of Bacillus cereus (eg Var. sotto) do not cause hemolysis of erythrocytes, while many other types of spore aerobes have this property.

Bacillus mycoides

Bacillus mycoides is a species of Bacillus cereus. Sticks (sometimes form chains) 1.2-6 µm long, 0.8 µm wide, mobile until spore formation (a feature is characteristic of all putrefactive spore-forming aerobes), form spores, do not form capsules, positively stain according to Gram (some varieties of Bacillus mycoides Gram-negative). Aerobe, grey-white rhizomatous colonies grow on MPA, resembling the mycelium of a fungus Some varieties (for example, Bacillus mycoides roseus) form a red or pinkish-brown pigment, when growing on MPA, all varieties of Bacillus mycoides form a film and a hard-to-break sediment, broth at the same time remains transparent. The pH range at which Bacillus mycoides can grow is wide. In the pH range from 7 to 9.5, all strains of this microorganism, without exception, give intensive growth. An acidic environment stops development. The temperature optimum for their development is 30-32°C. They can develop in a wide range of temperatures (from 10 to 45°C). The enzymatic properties of Bacillus mycoides are pronounced: it liquefies gelatin, causes coagulation and peptonization of milk. Gives off ammonia and sometimes hydrogen sulfide. Does not form indole. It causes hemolysis of erythrocytes and hydrolysis of starch, ferments carbohydrates (glucose, sucrose, galactose, lactose, dulcitol, inulin, arabinose), but does not break down mannitol. Breaks down glycerin.

Bacillus mesentericus

A rough rod with rounded ends, 1.6-6 microns long, 0.5-0.8 microns wide, mobile, forms spores, does not form capsules, gram-positive. Aerob, on MPA grow juicy, with a wrinkled surface, mucous colonies of dull color (gray-white) with a wavy edge. Separate strains of Bacillus mesentericus form a gray-brown, brown or brown pigment; causes a slight haze of the BCH and the formation of a film; there is no hemolysis in the blood broth. The optimal reaction is pH 6.5-7.5; at pH 5.0, vital activity stops. The optimum growth temperature is 36-45°C. Liquefies gelatin, coagulates and peptonizes milk. During the decomposition of proteins, it releases a lot of hydrogen sulfide. Indole does not form. Causes hydrolysis of starch. Does not ferment glucose and lactose.

Bacillus megatherium

Rough stick size 3,5- 7X1.5-2 µm. It is located singly, in pairs or in chains, mobile Forms spores, does not form capsules, Gram-positive. Aerob, on MPA grow matte colonies (gray-white). Smooth, shiny, with smooth edges; causes turbidity of the BCH with the appearance of a slight sediment. The microbe is sensitive to the acid reaction of the environment. The optimum development temperature is 25-30°C. Quickly liquefies gelatin, coagulates and peptonizes milk. It emits hydrogen sulfide, ammonia, but does not form indole. Causes hemolysis of erythrocytes and hydrolyzes starch. On media with glucose and lactose gives an acid reaction.

Bacillus subtilis

A short stick with rounded ends, 3-5X0.6 microns in size, sometimes located in chains, mobile, forms spores, does not form capsules, gram-positive. Aerobe, during growth on MPA, dry, bumpy colonies of a matte color are formed. In liquid media, a wrinkled whitish film appears on the surface, the MPB first becomes cloudy and then becomes transparent. Causes blue litmus milk. The microbe is sensitive to the acid reaction of the environment. The optimal development temperature is 37°C, but it can also develop at temperatures slightly above 0°C. It is characterized by high proteolytic activity: it liquefies gelatin and clotted blood serum; coagulates and peptonizes milk; emits large amounts of ammonia, sometimes hydrogen sulfide, but does not form indole. Causes hydrolysis of starch, decomposes glycerin; gives an acid reaction on media with glucose, lactose, sucrose.

Putrefactive processes are an integral part of the circulation of substances on the planet. And it happens continuously thanks to tiny microorganisms. It is putrefactive bacteria that decompose the remains of animals, fertilize the soil. Of course, not everything is so rosy, because microorganisms can irreparably spoil food in the refrigerator or, worse, cause poisoning and intestinal dysbacteriosis.

What is decay?

Decay is the decomposition of protein compounds that are part of plant and animal organisms. In the process, mineral compounds are formed from complex organic substances:

hydrogen sulfide;
carbon dioxide;
ammonia;
methane;
water.

Rotting is always accompanied by an unpleasant odor. The more intense the "darling", the further the decomposition process went. What is the "aroma" emitted by the remains of a dead cat in the far corner of the yard.

An important factor for the development of microorganisms in nature is the type of nutrition. Putrefactive bacteria feed on ready-made organic substances, therefore they are called heterotrophs.

The most favorable temperature for decay ranges from 25-35°C. If the temperature bar is reduced to 4-6 ° C, then the vital activity of putrefactive bacteria can be significantly, but not completely, suspended. Only an increase in temperature within the range of 100°C can cause the death of microorganisms.

But at very low temperatures, decay completely stops. Scientists have repeatedly found in the frozen ground of the Far North the bodies of ancient people and mammoths, which have been remarkably preserved, despite the past millennia.

Cleaners of nature

In nature, putrefactive bacteria play the role of orderlies. A huge amount of organic waste is collected around the world:

animal remains;
fallen leaves;
fallen trees;
broken branches;
straw.

What would happen to the inhabitants of the Earth, if there were no little cleaners? The planet would simply turn into a landfill unsuitable for life. But putrid prokaryotes honestly do their job in nature, turning dead organic matter into humus. It is not only rich in useful substances, but also sticks together lumps of earth, giving them strength. Therefore, the soil is not washed away by water, but, on the contrary, lingers in it. Plants receive life-giving moisture and nutrition dissolved in water.

Man's helpers

Man has long resorted to the help of putrefactive bacteria in agriculture. Without them, one cannot grow a rich crop of grain, one cannot breed goats and sheep, one cannot get milk.

But it is interesting that putrefactive processes are also used in technical production. For example, when dressing skins, they are deliberately subjected to decay. Skins treated in this way can be easily cleaned of wool, tanned and softened.

But putrefactive microorganisms can also cause significant harm to the economy. Microbes love to eat human food. And this means that food will simply be spoiled. Their use becomes hazardous to health, because it can lead to severe poisoning, which will require long-term treatment.

You can secure your food stocks with the help of:

freezing;
drying;
pasteurization.

The human body is in danger

The process of decay, sadly, affects the human body from the inside. The center of localization of putrefactive bacteria is the intestine. This is where undigested food decomposes and releases toxins. The liver and kidneys, as best they can, hold back the pressure of toxic substances. But they are sometimes unable to cope with overloads, and then a disorder in the work of internal organs begins, requiring immediate treatment.

The first target is the central nervous system. People often complain about these types of ailments:

irritability;
headache;
constant fatigue.

Constant poisoning of the body with toxins from the intestines significantly accelerates aging. Many diseases are significantly "younger" due to the constant damage to the liver and kidneys by toxic substances.

For many decades, doctors have been mercilessly fighting putrefactive bacteria in the intestines with the most extraordinary methods of treatment. For example, patients underwent surgery to remove the large intestine. Of course, this type of procedure did not give any effect, but there were many complications.

Modern science has come to the conclusion that it is possible to restore the metabolism in the intestines with the help of lactic acid bacteria. It is believed that the acidophilus bacillus is most actively fighting them.

Therefore, the treatment and prevention of intestinal dysbacteriosis must be accompanied by fermented milk products:

kefir;
acidophilic milk;
acidophilic yogurt;
acidophilus paste.

It is easy to prepare them at home from pasteurized milk and acidophilus starter, which can be purchased at a pharmacy. The composition of the starter includes dried acidophilus bacteria, packed in a sealed container.

The pharmaceutical industry offers its products for the treatment of intestinal dysbiosis. Drugs based on bifidobacteria appeared in pharmacy chains. They have a complex effect on the entire body, and not only suppress putrefactive microbes, but also improve metabolism, promote the synthesis of vitamins, and heal ulcers in the stomach and intestines.

Can you drink milk?

Disputes around the expediency of milk consumption by scientists have been going on for many years. The best minds of mankind divided into opponents and defenders of this product, but they did not come to a consensus.

The human body is programmed from birth to consume milk. This is the main food for babies in the first year of life. But over time, changes occur in the body, and it loses the ability to digest many components of milk.

If you really want to treat yourself, you will have to take into account that milk is an independent dish. A delicacy familiar from childhood, milk with a sweet bun or fresh bread, unfortunately, is not available to adults. Getting into the acidic environment of the stomach, the milk instantly curdles, envelops the walls and does not allow the rest of the food to be digested for 2 hours. This provokes decay, the formation of gases and toxins, and subsequently problems in the intestines and long-term treatment.

YEAST

The classification of yeasts is based on differences in the nature of their vegetative reproduction (division, budding). sporulation, as well as morphological and physiological features.

Korolev (1932) divided the yeast found in dairy products into three groups according to their biochemical properties.

First group- yeast that is not capable of alcoholic fermentation, although it consumes some carbohydrates by direct oxidation; these include Mycoderma spp., the colored non-spore yeast Tornla.

Most yeasts prefer an acidic environment for their development. Therefore, in fermented milk products, the conditions are favorable for them.