GENERAL DESCRIPTION OF MICROORGANISMS
The microflora of foods at refrigerated storage may be represented by bacteria, actinomycetes, molds and yeasts.
Bacteria - are single-celled organisms, whose dimensions are expressed in microns or tenths of a micron (μ = 0,001 mm). The shape of the cells of the bacteria are spherical, rod-shaped and crimped. On food bacteria are found primarily spherical and rod-shaped. The bacteria are called cocci spherical shape. Depending on the location of the cells are distinguished: micrococci (Micrococcus) - from the sensible-cells; diplococci (Diplococcus) - paired cells; streptococci (Streptococcus) - cells in the form of chains; staphylococci (Staphylococcus) -skoplenie cocci in a bunch.
Rod-shaped bacteria are distinguished primarily by the ability to form spores. Spore - is the intracellular formation of rod-shaped bodies of many bacteria. Disputes usually appear under adverse propagation conditions. They are resistant to the harmful effects of the environment. Under favorable conditions, spores germinate and the bacterial cells are formed. Spore-forming bacteria called bacillus.
Some rod-shaped bacteria have flagella or cilia with which they move. There are moving and still bacteria. The concept of the bacteria used in a more narrow sense - as the bessporovye rod-shaped. Spherical and rod-shaped bacteria reproduce by dividing into two cells of the adult equivalent "daughter." Under optimal conditions for the reproduction process of growth and division of bacterial cells lasts 20-30 minutes.
During the multiplication of bacteria on solid media or product formed cell mass, which becomes visible to the naked eye. This cluster of cells called colonies. By merging, the colonies form a film or other mucous consistency. The substrates are liquids turbidity, flake, pellet or film. Bacteria are distinguished and determined by a number of morphological and biochemical parameters. By morphological parameters include the shape, size; for rod-shaped bacteria -
spore formation, mobility, presence and location of flagella and cilia, the type, the color of the colonies, medium staining and so. d.
By the ability to take and hold the main paint bacteria are divided into two groups. Bacteria possessing such capability are called Gram-positive (Gram researcher named); not having the ability to be painted - Gram.
Fig. 1. Mould: and - Penicillium,
b - Cladosporium herbarum,
b - Thamnidium
This indicator is one of the main bacteria at recognition.
By biochemical parameters include the ability to change the carbohydrates, proteins, fats, the ratio of oxygen to the air, and others. The bacteria are also divided on the basis of pathogenicity and toxigenicity.
The species and number of bacteria belonging group particularly toxigenic pathogenic and can be determined only by their reactions with serum (serum) blood (serotypes) obtained from the organism who underwent disease or poisoning.
In recent years, the characteristics of microorganisms added to their attitude to antibiotics.
Only a few of the bacteria can be determined by one form or any other characteristic. Determination of many species can be produced only in the aggregate a variety of symptoms.
Molds are more complex in structure. Typical molds have a vegetative body, or mycelium, which is a loose or dense felt-like plexus of thin filaments - hyphae. Aerial or fruiting hyphae (sporangiophores or conidiophores) rise from the mycelium, on the tops of which fruit bodies with spores or conidia are formed. From bacterial spores, they differ in the nature of education and properties. Molds multiply by dividing hyphae, spores and conidia. On products with refrigerated storage, molds of the penicillium genus (Penicillium), mucor (Mucor, Rhizopus and Thamnidium), cladosporium (Cladosporium) and others are most often found.
(Fig. 1 and 2).
The mold penicillium have racemose form conidiophores.
On the products and environments, they are growing at the beginning of development in the form of colonies, or whitish plaque. Later they acquire their characteristic color. For many molds of this kind it has blue-green color.
Mukorovye molds are characterized by a cobwebby or furry coating of grayish-smoky color rising above the substrate, with black or brown spotted sporangia, which are small, but visible under the magnifying glass. In the form of fruiting in the form of heads, these molds are called capitate. Of this group, mold tannidium (Thamnidium) is of great importance, although it is less common and less common than others. With the growth of this mold on meat there is an unpleasant smell. Microscopically, tannidium differs from mukor by the presence of two types of sporangia: a large, main sporangia on top, and small sporangia (sporangioles) on lateral branches.
Of great importance in the refrigeration storage is mold kladosporium gerbarum (Cladosporium herbarum). On the surface of this substrate in the form of mold growing plaque velvety dark colored bottle. With the growth in the meat and dairy products, it forms a dark, almost black spots, deeply penetrating into the substrate. This is especially noticeable on the frozen mutton.
For other molds it will be made in the characterization of the microflora of certain types of products.
Due to the contact with the soil particles and dust foods may be infected and actinomycetes (Actinomyces), or fungal radiant which on further features similar to those of bacteria, on the other - with the molds. Body
It is a filamentous actinomycetes formation (diameter about 1μ), diverging from a central point of growth in the form of beams (Fig. 3).
On nutrient media initially actinomycetes grow in dense, fused with the substrate leatherback colonies. Later on in the majority of these colonies of actinomycetes formed a well-developed aerial mycelium (fluffy or velvety and powdery) form spores similar to those of mold spores.
The growth of many actinomycetes is detected by the characteristic earthy smell.
Yeasts are single-celled organisms, most often oval or round shape. According to the economic value of wild yeast and distinguished cultural. Wild yeast, preferably a round shape, are found on the products under refrigerated storage. Cultural yeast used in the fermentation industry.
yeast cells larger than most bacteria. Wild yeasts reproduce by budding, in adult cells, small cells are formed in the form of kidney. Become adults, they give a new kidney, and so on. D. From one parent may spun off a few cells (Fig. 4),
Microorganisms can grow and proliferate in a very wide range of temperatures. However, for each group (genus or even family) there is a certain upper and lower temperature limits growth and optimum temperature at which the reproduction speed is the greatest.
With respect to the temperature of all micro-organisms can be divided into three groups: thermophiles, mesophiles and crazy p o p l and s. Thermophiles multiply at temperatures from 20
Active growth of different groups of psychrophilic microorganisms on the meat, depending on the temperature, with humidity 80%
|The timing of growth days|
|Temperature, ° C||bacteria||molds||yeast Torul||aktynomy-||Time poyaleniya damage signs, days||The composition of the microflora|
|-0,5||7||14||6||5||14||Mould: tamnidium, Aspergillus, Mucor, oospore; Yeast: rodotorula; bacteria: Pseudomonas, ahromobakter, micrococci|
|-1,1||7||14||6||6||24||Mould: the same and R. nigricans; bacteria: Pseudomonas 20%, ahromobakter 70%, flavobacterium 10%|
|-2,7ч-1,6||13||30||25||25||50||Mould: the same; bacteria: Pseudomonas 50%, ahromobakter 50%|
|-3,3т-2,2||25||25||25||43||Mould: tamnidium, Aspergillus, R. nigricans; Yeast: Togrul; bacteria: ahromobakter 100% and aktinominety|
|-5,5ч-4,4||135||65||60||No||155||Mould: tamnidium, Aspergillus, R. nigricans, Pe- nitsillium, sporotri- hum, kladosporium; yeast: white, bacteria: ahromobakter|
|-7.2ч- -6,1||167||65||105||No||135||The same|
|-7,7 hours-6,6||No||144||No||No||190||Uncertain white mold|
|-9,4 : -8,3||No||144||No||No||170||Spot the growth of white mold|
|- 11,1ч - 10||No||144||No||No||260||Uncertain white mold|
|- 14,4ч- -13,3||No||No||No||No||St. 500|
to 80 °, optimum around 50-55 °; mezofily - at temperatures of up to 45 5-10 °, optimum around 24-40 °; psihrofily - by 25-35 ° to -5 -s 10 °, optimum around 10-20 °. In holodilʹnom Storage LARGEST interest predstavlyayut psihrofilʹnye mikroorganizmy.
Temperature minimum growth of different groups of psychrophilic microorganisms shown in Table. 1.
bacteria. By psychrophilic bessporovye includes many gram-negative bacteria are mobile and immobile. As the prevalence and the number of them to foods at refrigerated storage (chilled meat, fish, milk, eggs and non-standard meat, fish, dairy and egg products), the first place is occupied by bacteria belonging to the genus Pseudomonas (of Pseudomonas) and ahromobakter (Achromobacter). In much smaller quantities occurs in flavobakterium products (Flavobacterium). Less frequently and in small amounts - alkaligenes (Alcaligenes), aerobakter (Aerobacter) and some micrococci.
Fig. 5. Pseudomonas (micrograph)
The bacteria Pseudomonas and Achromobacter grow on media and products in the form of a translucent glossy surface colonies or film or slime gray, yellow and brown. Several species Pseudomonas (fluorescing bacteria) cause a change (greening and browning) the color of the environment.
According to the modern classification [1, 2] to Pseudomonas include all non-staining and coloring environment motile bacteria having polar flagella (Fig. 5).
Differentiation between non-staining and coloring environment Pseudomonas recommended against their antibiotic penicillin and Terramycin, guided by the following scheme
|Penicillin 2,5 mejd. U.||cin 10 and|
|chromogenic Pseudomonas||— +||+|
|Do not forming pigment Pseudomonas||-||+|
Note. Signs indicate: -nechuvstvitelnye; + Sensitive; ++ Very sensitive.
Colorless and coloring environment fixed and mobile bacteria that move using flagella, located throughout the body surface (peritrichous), classified as Achromobacter
Table 2. Characteristics of the different families of non-spore bacteria to antibiotics and mobility 
|family||Penicillin (2,5 mejd. U).||Streptomycin (80)||Xloram- fenikol (100)||Mobility|
|Pseudomonadaceae||+||OR +||Mobile (flagella on|
|IG Petritskaya or mobility|
The hallmark of Pseudomonas and Achromobacter nonsporeformers among other gram-negative bacteria is their relation to the three antibiotics (Table. 2).
The bacteria Pseudomonas and Achromobacter different attitude to the tetracycline antibiotics. Thus, in poultry, not treated with antibiotics, and treated with oxytetracycline, during storage at 1 ° coloring were not predominant environment Pseudomonas; on poultry treated with chlortetracycline, prevailing were Achromobacter .
Table 3. The relative sensitivity of different bacterial species to gamma-rays from the source So00 (1640 p / min) 
|Relative sensitivity of different bacteria to gamma rays from Co00 source (1640 r / min) |
|organisms||Exposure to 63% solution of cell death, min.|
|Micr. pyogenes var. albus . .||13|
|Corynebacterium xerose . . .||18|
|Micr. pyogenes var. aureus . .||20|
|Bacillus thermoacidurans . .||39|
|Streptococcus faecalis ...||28|
Varying the ratio of various bacteria to antibiotics, even if they belong to the same group - psychrophiles shows how little it is important to define at least a tribal affiliation of the microorganism.
Psychrophilic microorganisms relatively unstable to radiation (table. 3, 4),
Table 4. Change of qualitative composition of the bacterial flora (in%) on the exposed fish (M rad) during storage at a temperature of 0 ° 
|Change of qualitative composition of the bacterial flora (in %) on irradiated fish (M rad) in during storage at a temperature of 0 ° |
|The name of the bacteria||Undressed after filetirovaniâ||irradiated 0,25 M rad after treatment||Cured aureomycin after immersion||Aureomycin treated and irradiated 0,25 M rad after treatment|
|through 1 day||through 23 days||through 1 day||through 21 day||through 1 day||By||through 6 days||through|
|23 day||20 days|
|Flavobacterium . . .||11||-||8||-||5||1|
|Corynebacterium . . .||6||1||6||1||12||8||-||-|
The bacteria Pseudomonas and Achromobacter characterized by the following temperature: minimum temperature increase of up to 0 -5 °, optimum - by up to 20 10 ° and the maximum - from up to 35 25 °. Some species can grow on non-frozen media to -8 - * 9 °. At a temperature of ° 63 psychrophiles 30 die within minutes.
Most of these bacteria are aerobic groups: their anaerobic growth slows down or ceases altogether. The growth is also delayed with decreasing values of pH (below 5,5) and content in 5-8% NaCl medium . Many of these bacteria are able to thin the meat-gelatin. The minced meat is stored until spoilage during 0 °, bacteria liquefy gelatin, contained up to 75%. Approximately the same number of bacteria, liquefy gelatin contained in the microflora isolated from marine fish .
Many species of Pseudomonas and Achromobacter have the ability to break down proteins and rank third in the series of proteolytically-yaktivnyh bacteria (after anaerobic bacilli and Proteus). Achromobacter and Pseudomonas bacteria are pathogens of major damage to the protein products during storage under refrigeration. Food spoilage, manifested in the formation of foreign smell, can be called, however, not only the proteolytic bacteria, but also those in the group who do not possess proteolytic .
Characterized Pseudomonas and other features. Some species ferments glucose, sometimes with gas formation. Some actively break down fats. Some of them, with alkalization or by acidification to cause coagulation of the milk, the other do not change it, and so on. D. Among the main causative agents of spoilage of protein products (milk, dairy products, fish, meat) in the refrigeration storage include Pseudomonas putrefatsiens (Ps. Putrefaciens) pseudomonal Fraga (Ps. Frags) and pseudomonal fluorescens (Ps. Fluorescens) [7, 10, 11].
Ps. Putrefaciens is characterized by the reddish-brown color of the deep colonies on the agar and the absence of pigment staining the medium, the ability to thin meat-peptone gelatin, the absence or poor growth at a temperature of 37 °, the rapid recovery of litmus milk and a strong odor of decomposition. In agar with sugar, when planting with a prick, some cultures gave acid in the lower layers and alkalinization on the surface. Adding salt to the agar medium up to 4-5% improves growth. Above 8% growth is delayed. In butter, they cause loss of flavor as a result of the destruction of diacetyl, and then give the smell of decomposition. Like all psychrophilic bacteria, Ps. Putrefaciens easily breaks down when heated. In milk at 61,5 ° they were destroyed within 2 min., And most during 1 min.
Ps. fragi, unlike Ps. putrefaciens, causes milk coagulation. Ps. fluorescens is characterized by a pronounced ability to allocate to the substrate green pigment. These bacteria meat-liquefy gelatin, do not grow or do not grow at 37 °, without causing coagulation of milk alkalinization.
Bacteria of the genus Achromobacter may slightly acidify the milk, but not enough to roll. Usually the reaction of milk remains the same or becomes alkaline. They can form acid from hexoses (glucose) without gas evolution.
Close to the genus Achromobacter are Alcaligenes bacteria. Ot'Achromobacter They differ in that the milk and basified not form acids from carbohydrates .
Psychrophilic bacteria contained in soil, water (fresh and especially in sea water), airborne. At the enterprises they shatters equipment, tools, containers, in large quantities contained in products when you receive them in storage. Actively breeding psychrophilic bacteria on foods with little acidity: meat, fish, and non-acidic dairy and vegetables. The acidic products - berries, fruits, tomatoes, milk products - actively reproduces only a small part of psychrophilic bacteria.
The content of psychrophilic bacteria in the products illustrated by the following example.
From bacteria isolated from sardines, at a temperature of from 7 ° growing it grew at room temperature 90%, at 4 ° - 77%, at 0 ° -66% and -2 ° -64%.
The composition of the microflora of meat products received in the trading network, the ability to reproduce is shown in the Table. 5.
Composition psychrophilic bacteria on different products can be seen in Table. 6.
Mould. By psychrophilic microorganisms include most molds. Molds grow quite actively and frozen foods. The most common among them Pénicillium, then Nucor, Rhіzorus, Thamnidium, Sladosorium and others. The last two types of molds cease to reproduce only about -10 ° .
T able 5. The composition of the microflora and minced cutlets for the ability to grow at different temperatures (in% of the number of bacteria growing at ambient temperature)
|Meat semi-finished products||crop cultivation temperature, ° C|
|№ 2||> 69||69||34||30|
|№ 6||> 87||87||64||60|
Mold fall on products during manufacture and storage at refrigerated.
Table 6. Composition of psychrophilic bacteria in different product (in%)
|Raw milk is stored at 3-5 ° within 1-3 days .||15,1||45,3||16,8||19,5||з;з|
|The oil (gram-negative bacteria affecting milk)||-21||41||27,6||3,7||5;8|
|The surface of the two kinds of flat fish (the North Sea) ||53-60||13-14||6-8||5-9||1-3||1-2||11-14|
|Freshly caught cod (North Sea) ||51,5||41,3||1,5||0,7||1||4|
|Surface birds : at the beginning of storage.||> 35-||-||-25||-10||- 5||-10|
Mould as yeast proliferate mainly in acidic foods (berries, fruits, juices, milk products), as well as meat and fish. As aerobic, they grow mainly on the surface. In the presence of air they can grow well in the deep layers of the product; for example, in a poorly evolved in oil, they are able to develop inside the monolith.
Yeast and molds are not resistant to heat. So, the debate (and conidia) molds are destroyed at temperatures significantly lower than 100 °. The spores of many species died out mold in milk during 30-minute exposure at 55,5 °; Some squeezed at 60 °, but 62,7 ° die out completely. According to others, when ° 62,7 30 die out within seconds. few mold spores, when 68,3 ° during the same time - the majority, and at 74-80 ° all died .
The presence of molds in foods subjected to pasteurization, it indicates poor holding or subsequent pollution. Some molds are active towards proteins and fats. Great lipolytic ability of different lactic mold Oidium lactis. Some mold using sugar and oxidize organic acids.
Yeasts and actinomycetes. Psychrophilic yeast - Torul ( "wild yeast"), as well as psychrophilic bacteria are bessporovymi. Psychrophilic yeast grow on all the products stored in refrigerators. Most often they occur and rapidly grow in acidic foods. Actinomycetes grow at temperatures up to -2; -3 °.
Mesophilic microorganisms do not grow in a cold-storage products; minimum temperature of growth 5-10 °. These include spore forming aerobic and anaerobic bacteria, many coccoid form, the lactic acid bacteria and others. This group also includes pathogenic bacteria, coliform bacteria, Proteus, staphylococci, faecal streptococci and so on. D.
Higher temperatures 0 ° cease to multiply the cultural race of yeast and certain types of mold (Aspergillus niger).
Mesophilic microorganisms in conditions of refrigerated storage can not cause changes in the commercial quality of products; Of this group, the most important are those bacteria that can adversely affect human health. According to their content, a number of products judge the quality of the latter from a sanitary and hygienic point of view. Some of this group of bacteria (for example, salmonella) are pathogenic; Others (for example, E. coli) serve as an indicator of the possible presence of pathogenic bacteria, and sometimes they themselves can cause the disease, while others (for example, certain strains of staphylococci and botulinum bacillus) can cause the formation of toxins in foods. Without causing changes in the product at low temperatures, these bacteria begin to show activity when the temperature rises.
The need for special attention to this bacteria cause more difficulty identifying their own and their metabolic products (toxins).
Coliform bacteria. As health indicators foods most commonly accepted coliform bacteria or typical (sewage) coli.
These bacteria are found in the intestines of humans and animals, from entering the environment and non-compliance with sanitary regulations - in products.
Coliform bacteria are divided into a number of species. Of these, the main ones are the typical (sewage) coli Bact. coli-commune, American terminology or Escherichia coli, and Bact. coli-aerogenes, or Aerobacter aerogenes. Determination of species belonging of these bacteria is difficult. It is more expedient to determine the content in the products of all these groups of bacteria without installing species.
Bact. coli-commune differs from Bact. coli-aerogenes on the temperature minimum. The first stop growth of about 5 °, the second is closer to 0 °.
With a large accumulation of Bact. Coli-commune in the product (for example, in milk) often results in false lactic fermentation, and Bact. Coli-aerogenes - and mucus. A typical E. coli causes the decay of peptones with the formation of indole. In carbohydrate foods, E. coli strongly increase acidity (typical E. coli to pH <5,0 and coli-aerogenes to pH ~ 5), but they are unstable to acidic medium and in acidic products die quickly enough. With mild heating, they are destroyed. So, according to Airs and Johnson, from 174 strains of E. coli bacteria at 62 ° for 3 min. Survived 12 (7%); Tanner from 23 at 62 ° for 30 min. One strain survived; By Stark and Patterson from 505 crops at 60 ° for 30 min. 487 perished (96%); Of the remaining 18 at 61,5 ° for 30 min. 14 strains were destroyed and at 62 ° for 30 min-4.
These bacteria die off more quickly than many other non-spore frozen bacteria, particularly acidic products, wherein the concentration of acid is greatly increased as a result of water freezing. The butter at about -18 ° E. coli completely do not die within a few years.
Salmonellы. Bacteria of this type cause intestinal infectious disease type. Salmonella get into food when insufficiently rigorous veterinary-sanitary control in the field of raw materials processing and multiply in violation of technological and sanitary regime (insufficient heat treatment, slow cooling, storage at elevated temperatures, and so on. N.). These bacteria cease to proliferate npi temperature 5 °
Salmonella sensitive to heat treatment. Meat contaminated with Salmonella after provarkoy within 2,5 hours. It did not cause human disease . Some types of salmonella commonly found in eggs of waterfowl. Salmonella found in chicken eggs obtained from hens suffering salmonellosis .
Fyekalinyye stryeptokokki (enterococci). These bacteria can be read by a more reliable sanitary indicator of foods than the E. coli. They are also constantly contained in the intestines of humans and animals. The greatest practical importance in food microbiology is given to Str. Faecalis and Str. Liquefaciens, which are found in raw and pasteurized milk, milk powder and cheese, frozen vegetables and other products. The effect of these bacteria on the human body is not yet clear. Some believe that bacteria cause disease of the body, getting into the gastrointestinal tract; Others classify these bacteria as being toxic, capable of producing toxin in products.
Fecal streptococci are characterized by greater resistance to cold in comparison with E. coli. Thus, in the green beans at temperatures -17,8; -20, -29 ° faecal streptococci remained almost in the starting amount for more than 400 days .
According to the content of streptococci in frozen products more properly assessed the conditions of manufacture and storage of up to refrigerator available.
Canned hams isolated from fecal streptococci grown in the presence of bile 40% (at pH 9,6) and in the presence 6,5% NaCl. Their temperature range is from growth to 10 45 °. They kept heating at 60 30 ° within minutes.
П88 ° When they died within one minute .
Fecal streptococci are resistant to chlortetracycline and to the effects of ionizing radiation (see. Table. 3).
However. It - Nesporova motile bacteria. In response to the external environment and the impact of temperature close to Proteus bacteria coliform. Proteus growth stops at about 5 °. Only a few representatives can grow and at a temperature of about 0°
Proteus has a very active proteolytic; In this respect, it is second only to the anaerobic spore-forming bacteria. The Proteus group can meet and pathogenic strains. The presence of the bacteria Proteus is unacceptable in the finished meat products (culinary, cooked sausage, jelly, frozen culinary meat products, etc.).
Proteus bacteria resistant to the antibiotic biomitsin (chlortetracycline), so this drug is applicable to meat products only in low temperatures, or in combination with additional antibiotics.
Staphylococci. Staphylococci are globose non-sporey bacteria. Bacteria of the type Staphylococcus aureus (Staphylococcus aureus) may contain toxic strains. These bacteria stop multiplying at a temperature of about 7 °. In some cases, staphylococci can cause food poisoning, for example, when consuming ice cream and cream cake, some dairy (curd, cheese) and other products, if these products or their constituent parts are stored at a temperature above 7 °. Staphylococci can cause pustular diseases if they enter open wounds or weak mucous membranes.
Staphylococci are very common in nature.
Toxigenic Staphylococcus strains have been found in the nasopharynx more than 50% of healthy people . Therefore, the possibility of getting their products is very high.
In dairy products Staphylococci fall in the following cases: when the milk is obtained from cows suffering from mastitis; If dairy products are made without pre-pasteurization (such as yoghurt and cheese) or samoskvashivaniem (cottage cheese); by contamination of milk after pasteurization.
Aureus may be contaminated with large batches of dairy products due to the mixing of milk from mastitis cows with milk just milk yield.
The products can get staphylococci by persons suffering from pustular disease or are carriers of these bacteria. In order to prevent the breeding of staphylococci and the formation of the toxin products should not be stored for a long time above the minimum temperature of the breeding of bacteria.
Staphylococci very resistant to the action of both low and high temperatures. They can withstand heating at 100 ° for 35 min. Some strains of the dry heating medium and incubated fatty longer heating.
To kill bacteria in creams recommended for warming them with 90 ° within 20-25 minutes. or 220 ° for 15 min. . Persistent storage are not only bacteria but also toxins formed by them. This explains, for example, cases of poisoning or cream cheese after prolonged storage of the product at low temperatures, when the reproduction of the bacteria did not occur. The toxin withstand temperatures 100 ° (boiling water) to 20 minutes. and 120 ° in oily environments.
Staphylococcal toxin can be found in culinary products, if not in their manufacture or enforced cooling heat treatment.
The presence of staphylococcal toxin has no effect on product color and odor, and manifests itself only in painful symptoms of a person. The presence of the toxin may be determined by reaction kittens intravenous toxin. Determination of toxigenic staphylococci can be done on a range of indicators and by specific phages .
Staphylococci can grow in media with a high content of NaCl (Up to 9%). Therefore, they can multiply and salted products and environments. In order to identify staphylococcus content is added to the medium 7,5% NaS1. However, the identification of staphylococci in fish microflora which also reproduces at high salt content, is difficult.
Sporoobrazwyuşçïe anaerobic. These bacteria may be found in some types of products. If the products are stored prior to cooling and anaerobic favorable for growth of these bacteria temperatures or cooled very slowly, the toxins can be formed therein. Such cases, however, there are only very rarely and under abnormal conditions of storage.
In case of contact cold storage products containing anaerobic bacteria toxins, toxin activity can be maintained for a long time (over several years).
Spore-forming aerobes. These bacteria reproduction is stopped at a temperature above 5 °. However, they may to some extent adversely affect the product in the growth conditions below the minimum temperature. This effect may occur because of the strong collagenase and gelatinase activity in the tissue softening. However, in order for this action affected, especially at low temperatures, the content of these bacteria should be very high. Therefore, their storage in refrigeration value is extremely limited.