The total microbial number is some ml. Total microbial count for drinking water rationing
Table 6 - Number of colonies per MPA at 37°C
Formula 1 is used to calculate the concentration of TMP at a temperature of 37°C.
X (MCH, 37°C) = = 110.81 cfu/ml
Figure 18 - Whole sample Figure 19 - Concentration 10 -1
Figure 20 - Concentration 10 -2
At a temperature of 37°C, three types of colonies grew on the plates:
Type 1: large colonies, there are dotted and small ones; colony shape
– round; the profile of the colonies is convex; the edge of the colonies is smooth; the structure of the colonies is homogeneous; the consistency of the colonies is soft; the surface of the colonies is moist, smooth, shiny with gloss; colony transparency
– opaque; the color of the colonies is milky white. Gram stain revealed Gram-negative short rods.
type 2: medium colonies; the shape of the colonies is round; the profile of the colonies is convex; the edge of the colonies is smooth; the structure of the colonies is homogeneous; the consistency of the colonies is soft; the surface of the colonies is moist, smooth, shiny with gloss; transparency of colonies - cloudy; colony color
- orange. Gram stain revealed Gram-positive long rods.
Type 3: the shape of the colonies is round; profile of colonies - growing into the substrate; the structure of the colonies is homogeneous; transparency of colonies - transparent; the color of the colonies is milky white. Gram stain revealed Gram-positive short rods.
Figure 21 - drug type 1
Figure 23 - preparation of type 3 colonies
Table 7 - Number of colonies per MPA at 22°С
Formula 1 is used to calculate the concentration of TMP at a temperature of 22°C.
X (MCH, 22°C) = = 130.63 cfu/ml
where Y is the ratio of TMP at a temperature of 22°С and TMP at a temperature of 37°С, [CFU/ml]
Y = cfu/ml
Figure 24 - Whole sample Figure 25 - Concentration 10 -1
Figure 26 - Concentration 10 -2
At a temperature of 22°C, three types of colonies grew on the plates:
Type 1: large colonies, there are dotted ones; colony shape
- incorrect; the profile of the colonies is curved; the edge of the colonies is smooth; the structure of the colonies is homogeneous; the consistency of the colonies is soft; the surface of the colonies is moist, smooth, shiny with gloss; transparency of colonies - cloudy; the color of the colonies is cream. Gram stain revealed Gram-negative short rods.
type 2: large colonies; the shape of the colonies is round; the profile of the colonies is flat; the edge of the colonies is wrong; the structure of the colonies is heterogeneous; the consistency of the colonies is soft; the surface of the colonies is moist, rough, shiny with gloss; transparency of colonies - opaque; the color of the colonies is milky white. Gram stain revealed Gram-negative short rods.
type 3: large colonies; the shape of the colonies is round; the profile of the colonies is curved; the edge of the colonies is smooth; the structure of the colonies is homogeneous; the consistency of the colonies is soft; the surface of the colonies is moist, smooth, shiny with gloss; transparency of colonies - opaque; the color of the colonies is milky white. Gram stain revealed Gram-negative short rods.
Figure 27 - type 1 drug
Figure 29 - preparation of 3 types of colonies
Table 8 - Comparative characteristics obtained indicators with the requirements for the composition and properties of water in water bodies of recreational water use
| № | Indicators | Data received | Norm for recreational water use |
| floating impurities | Missing | Films of oil products, oils, fats and accumulation of other impurities should not be detected on the surface of the water. | |
| Smells | The intensity is weak (2 points) | Water should not acquire odors with an intensity of more than 2 points, directly detectable | |
| Hydrogen index (pH) | 8.2 units pH | Should not go beyond (6.5-8.5) units. pH | |
| Common coliform bacteria (TCB) | 3200 cfu/100ml | Not more than 500 cfu/100 ml | |
| Total Microbial Count (TMC) at 22°C | 130.63 cfu/ml. | Not standardized | |
| Total microbial count (TMC) at 37°C | 110.81 cfu/ml | ||
| Ratio TMP (22°C): TMP (37°C) | 1.2 cfu/ml | More than 4 cfu / ml |
Conclusions:
I. We studied the physical and chemical parameters of a water sample from a pond in Boroviki, the city of Kirov:
1. The odor character of the water sample is earthy. At a temperature of 22°C, the odor intensity is weak, and at 60°C, it is noticeable. The intensity of the smell is normal.
2. The pH value of the water sample was 8.2 units. pH, therefore, the environment is slightly alkaline, corresponds to the norm.
3. No floating impurities were found in the water sample.
II. The microbiological parameters of the studied water sample were determined:
1. The concentration of total coliform bacteria (TBC) was 32 CFU/ml. Which exceeds the norm for recreational water use by 6.5 times.
2. When determining thermotolerant coliform bacteria (TCB) at a temperature of 37°C, colonies grew from all dilutions; Gram staining of smears revealed gram-negative short rods in all dilutions. At a temperature of 44°C, colonies grew only from a dilution with a concentration of 10 -3 , Gram staining of smears revealed gram-negative long rods.
3. The oxidase test is positive in a culture with a concentration of 0.09 grown at a temperature of 37°C. In other cultures, the oxidase test is negative.
4. At 37°C, 3 types of colonies grew on MPA plates. Gram stain revealed gram-negative and gram-positive rods.
5. Total microbial count (TMC) at 37°C was 110.81 cfu/ml.
6. At 22°C, 3 types of colonies grew on MPA plates. Gram stain revealed gram-negative rods.
7. Total microbial count (TMC) at 22°C was 130.63 cfu/ml.
8. The ratio of TMP at 22°C to TMP at 37°C was 1.2 CFU/mL. Therefore, the reservoir is not capable of self-purification.
STYLAB offers test wipes, test pads and microbiological stamps for the determination of TMP and QMAFAnM in various samples.
The total microbial count (TMC) is an indicator for assessing the total bacterial load. This is one of the main indicators determined in the course of sanitary and microbiological studies. This is the total amount of all that are in 1 ml or 1 cm 3 of the sample. Its value is expressed in colony-forming units: CFU/ml or CFU/cm 3 . A colony forming unit is a microorganism that forms a colony during reproduction.
It is believed that the higher the TMF, the more likely the presence of pathogens in the object under study. In fact, the value of this indicator is also influenced by saprotrophs, which prevent the development of pathogenic microorganisms, and TMF unambiguously correlates only with the degree of contamination of the object. organic matter. However, this is an important sanitary indicator, since it allows you to evaluate the purity and quality of disinfection of water, surfaces, equipment and other environmental objects.
In food products, the number of mesophilic aerobic and facultative anaerobic organisms (QMAFAnM) is usually determined. Aerobic microorganisms are living things that require oxygen to survive. Facultative aerobes can live and reproduce both in the presence of oxygen and without it. Sometimes the term QMAFAnM is used as a synonym for MCH. Its value is expressed in CFU/g or CFU/cm 3 . QMAFAnM allows you to evaluate the conditions of storage and transportation of food products. TMC and QMAFAnM are not applicable to evaluate products with their own microflora, for example, lactic acid products, beer, kvass, etc.
To determine TMP and QMAFAnM, a sample of the initial concentration and several of its consecutive tenfold dilutions in sterile water or solution are sown on the medium. This is necessary in case there are a lot of microorganisms in the initial sample, and it will be impossible to distinguish the colonies formed by them. To determine KMAFanM, we recommend using test wipes. It is also possible to determine TMF on solid surfaces by the imprint method using microbiological stamps.
The effectiveness of disinfectants can also be assessed by determining TMP. To do this, it is necessary to use a medium with substances that neutralize their action, since when the effectiveness of disinfectants decreases, they do not destroy microorganisms, but only inhibit their growth. On ordinary media, such organisms do not have time to form colonies. Microbiological stamps are intended for such evaluation.
IN Russian Federation and the countries of the Customs Union, the parameters of the MCH and QMAFAnM should not exceed those established by the TR CU "On Food Safety" and other technical regulations of the Customs Union. Up-to-date legal information can be found on the website
Objective: determine the microbial count of tap water.
The microbial number gives an idea of the total contamination of water with aerobic saprophytes, which make up only a part of the total number of microbes in water. However, there is a direct relationship between the magnitude of the microbial number and the probability of the presence of pathogenic microorganisms in the water.
The microbial count of tap water should not exceed 50 bacterial colonies per 1 ml. It is determined by the method of sowing on a nutrient medium - meat-peptone agar (MPA). The method consists in the fact that in 1 ml of water bacteria are determined that are able to grow on nutrient agar at a temperature of 37 0 C for 24 hours, forming colonies visible at a magnification of 2–5 times. An analysis carried out in this way cannot completely determine all the bacteria in the water, but only those that develop under the conditions of the analysis. Therefore, the definition does not give an absolute, but a relative bacteriological characteristic of water. With this method, it is possible to compare the bacterial contamination of different places in a water source, as well as one place in different times of the year.
Instruments and equipment
Thermostat; microscope; Petri dishes; nutrient medium MPA; distilled water.
Materials: pond water and tap water.
Completing of the work
1 ml of the studied drinking water is introduced into the Petri dish with a pipette (if waste water is examined, it is diluted with sterile water several times), then the sample is poured into 10-12 ml of cooled nutrient meat-peptone agar (MPA), which has a temperature of approximately 45 0 C. The contents are quickly mixed , gently tilting and rotating the cup on the table surface. It is necessary to avoid the formation of air bubbles, inconspicuous parts of the bottom of the cup, the ingress of medium on the edges and lid of the cup. After solidification of the medium, the cup is placed in a thermostat and maintained at a temperature of 37 0 C for 24 hours. During this time, colonies grow in the Petri dish, which are visible at a magnification of 2-5 times. Usually grows from 30 to 300 colonies.
To count the number of colonies, the dish is placed upside down on a black background. To speed up the calculation of the number of colonies X, determine the number of colonies in 1 cm 2 and multiply this number by the area of \u200b\u200bthe cup
S = π r
where r is the radius of the cup.
X = nS
where n is the number of colonies.
According to the data obtained, the degree of water pollution is determined.
Table The degree of water pollution depending on the total number of bacteria
|
Water characteristic |
The number of bacteria in 1 ml |
|
very clean moderately polluted polluted very dirty |
|
|
NOTE: a has values from 1 to 9. |
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In relation to water from sources of natural origin, microorganisms are distinguished - saprobionts and catarobionts, which are considered as an indicator of microbiological pollution of water bodies. To the group of catarobionts(Katarobs) include microorganisms that live only in pure spring water. Saprobiont group(saprobes) makes up the microflora of all other fresh water bodies.
Saprobity is calledcertain physiological features a specific type of microorganisms that determine their ability to live in an aquatic environment contaminated with organic compounds. The saprobity indices for water bodies are calculated on the basis of the individual species saprobity of the organisms that make up the complex of their microflora.
The table below shows the dependence of the purity class and the level of pollution of natural water bodies on the microbiological indicators of their water.
Table 1
Indicators of microbiological contamination are applicable to many industries. Requirements for the cleanliness of reservoirs are regulated by GOSTs, TU (technical conditions), other regulatory documentation and have significant differences in relation to various objects. For example, the operation of a swimming pool is impossible without the development of a production control program. It must be coordinated with the head physician of the State Sanitary and Epidemiological Supervision of this administrative territorial unit and obtain permission from the management of the organization that is going to operate this swimming facility.
table 2
Table 3
Dear Sirs, if you have a need to correct microbiological contamination indicators in natural or industrial water, make a request to the company's specialists Waterman. We will develop an optimal water disinfection scheme.
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When analyzing water, it is necessary to control not only the content of toxic chemical substances, but also the number of microorganisms characterizing the bacteriological contamination of drinking water, TMF is the total microbial number. In the water of centralized water supply, this number should not exceed 50 CFU / ml, and in wells, wells - no more than 100 CFU / ml
Sanitary and microbiological research of water is carried out in a planned
order for the purpose of current surveillance, as well as for special epidemiological
kim testimony. The main objects of such research are:
Drinking water of the central water supply (tap water);
Drinking water of non-centralized water supply;
Water from surface and underground water sources;
Water of coastal zones of the seas;
Swimming pool water.
The main indicators for assessing the microbiological state of drinking water in accordance with the current regulatory documents are:
1. Total microbial count (TMC) - the number of mesophilic bacteria in 1 ml of water.
If the titer- the smallest volume of water (in ml) in which at least one living
microbial cell related to BGKP.
BGKP index- the amount of BGKP in 1 liter of water.
3. The number of spores of sulfite-reducing clostridia in 20 ml of water.
4. Number of coliphages in 100 ml of water.
Determination of TMC makes it possible to assess the level of microbiological contamination of drinking water. This indicator is indispensable for the urgent detection of massive microbial contamination.
Total microbial count- this is the number of mesophilic aerobic and facultative anaerobic microorganisms capable of forming colonies on nutrient agar at a temperature of 37 ° C and within 24 hours, visible at a twofold increase.
When determining the total microbial number, 1 ml of the test water is added to a sterile Petri dish and 10-12 ml of warm (44 ° C) molten nutrient agar is poured. The medium is gently mixed with water, uniformly and
without air bubbles distributing along the bottom of the cup, then cover with a lid and leave to solidify. Crops are incubated in a thermostat at 37 °C for 24 hours. Count the total number of colonies grown in both dishes and determine the average value. The final result is expressed as the number of colony forming units (CFU) in 1 ml of the test water. 1 ml of drinking water should contain no more than 50 CFU
Definition of BGKP
At the same time, common coliform bacteria - OKB and thermotolerant coliform bacteria - TKB are determined.
GKB are gram-negative, non-spore-forming rods that ferment lactose to acid and gas at 37°C for 24-48 hours. TKB are among the OKB, they have their signs, but I ferment at 44 ° C. For the determination of enterobacteria - the method of membrane filters or titration.
Microbial number - the main criteria for assessing the microbiological state of drinking water, based on the current regulatory documents, is TMC (total microbial number), which characterizes the number of aerobic and anaerobic bacteria in one milliliter of water, formed per day at a temperature of 37 degrees, in a nutrient medium. This indicator is virtually indispensable for the rapid detection of massive microbial contamination.
For determination of the total microbial number one milliliter of the test water is added to a sterile Petri dish, then 10-15 ml of warm (about 44 ° C) nutrient agar is poured in a molten form. The medium is carefully mixed with water, distributed evenly and without air bubbles over the bottom of the dish, then closed with a lid and left in the Petri dish until solidified. The same is done in the other cup. Sowing in a thermostat is incubated at a temperature of 37 ° C during the day. Then, at double magnification under a microscope, the total number of colonies grown in two cups is counted, and the average value is determined. In 1 ml of drinking water should not be more than 50 CFU.
