Fecal coliform is a kind of coliform, also known as heat-resistant coliform.
Fecal coliforms are a group of intestinal bacteria that grow in the intestines of human beings and warm-blooded animals, and are excreted with feces, accounting for more than 1/3 of the dry weight of feces, so they are called fecal coliforms. Water, food, cosmetics, soil, etc. polluted by feces contain a large number of such flora. If fecal coliform is detected, it means that it has been contaminated by feces.
coliform bacteria
1, coliform refers to a group of aerobic and anaerobic bacteria, which can decompose lactose at 37℃ for 24 hours to produce acid and gas. It mainly comes from human and animal feces, and can usually be used as an indicator of water and feces pollution.
2. Escherichia coli refers to gram-negative bacilli that can ferment lactose at 37℃ and produce acid and gas within 24h, including not only Escherichia coli, but also Enterobacter, Citrobacter and Klebsiella of Enterobacteriaceae.
3. Escherichia coli refers to a group of Gram-negative bacilli, which can ferment lactose to produce acid and gas within 24 hours under aerobic and facultative anaerobic conditions at 36℃. It mainly includes Escherichia coli, Citrobacter Watermelon, Klebsiella and Enterobacter cloacae of Enterobacteriaceae.
Literature source
Coliform group is not a taxonomic name of bacteriology, but a term in the field of sanitary bacteria. It does not represent a certain bacterium or a certain genus, but refers to a group of bacteria with certain characteristics related to fecal pollution. These bacteria are not completely consistent in biochemistry and serology. Defined as: Gram-negative bacilli that can decompose lactose to produce acid and gas at 37℃. It is generally believed that the bacteria of this flora can include Escherichia coli, Citrobacter, Klebsiella aerogenes and Enterobacter cloacae.
Escherichia coli is widely distributed in the feces of warm-blooded animals and in nature. The investigation shows that coliforms mostly exist in the feces of warm-blooded animals, places where people often move and places where feces are polluted. The pollution of human and animal feces to the external environment is the main reason for the existence of coliforms in nature. Typical Escherichia coli is dominant in feces, but there are many other types of Escherichia coli in the external environment.
Coliform group is put forward as an indicator of fecal contamination, and the detection of coliform group mainly indicates whether there is fecal contamination in food. The number of coliforms indicates the degree of fecal pollution and also reflects the harm to human health. Feces are human intestinal excreta, including the feces of healthy people and the feces of intestinal patients or carriers. Therefore, in addition to normal bacteria, there are some intestinal pathogens (such as Salmonella and Shigella) in feces. Therefore, if there is fecal pollution in food, it can be inferred that there is the possibility of intestinal pathogenic bacteria pollution in food, which lurks the threat of food poisoning and epidemic situation and must be regarded as a potential danger to human health.
Fecal coliforms and drinking water
According to the national drinking water standard, the number of coliforms in drinking water should not exceed 3 per liter, and the total number of bacteria should not exceed 100 per milliliter.
The fecal coliforms in Qingdao No.1 bathing beach exceeded the standard.
The fecal coliforms in Qingdao No.1 bathing beach exceeded the standard. Last week, the State Environmental Protection Administration released the water quality report of 28 beaches in coastal cities nationwide 16. The report shows that the first bathing beach in Qingdao is not suitable for swimming because the fecal coliform group exceeds the standard of 2000 /L, and the water quality is poor.
Detection method of fecal coliform bacteria
Fecal coliform is a subspecies of total coliform; Directly from feces, it can grow and reproduce at 44-44.5℃ and metabolize tryptophan into indole, and its other characteristics are the same as those of the total coliforms except heat resistance.
Bacteria in the total coliforms usually exist in water and soil in the natural environment, except in the intestines. But the most suitable temperature for these coliforms to live in the natural environment is about 25℃. If they are cultured at 37℃, they can still grow, but if the culture temperature is raised to 44.5℃, they will no longer grow. However, Escherichia coli directly from feces is used to growing at around 37℃, such as raising the culture temperature to 47℃. Therefore, E.coli in natural environment can be distinguished from E.coli in feces by increasing the culture temperature. The coliforms growing at 37℃, including those growing in feces, are called "total coliforms"). The coliforms that can still grow at 44.5℃ are called "fecal coliforms", and fecal coliforms are of great significance in hygiene.
1.5 Precautions for inspection
(1) Put the inoculated samples into a constant-temperature water bath box or a waterproof constant-temperature incubator, and the temperature in the box must reach the required temperature (44 1℃) before putting them in. If a constant temperature water bath box is used, its water surface should be higher than the surface of inoculum, and the Petri dish with filter membrane should sink to the bottom of the water bath box.
(2) The purity and quality of aniline blue in 2)MFC medium often affect the colony color. According to the test results, the color of fecal coliforms cultured with imported aniline blue plus O. 1g and domestic aniline blue plus 0.2g is typical. However, it is uncertain whether the performance of domestic aniline blue is equally stable. Therefore, before using the prepared culture medium, it is best to inoculate the typical fecal coliforms and observe the color of the contrast colonies.
Rosmarinic acid will decompose under high pressure. The prepared test solution should be kept at 2- 10℃ for no more than 2 weeks. If the color changes from dark red to brown, it should be discarded. If the contamination of miscellaneous bacteria is less, the addition or absence of rosanilic acid has no effect on the number of colonies and can be omitted. .
(3) The colonies growing on the filter membrane should not only choose blue colonies, but also choose light blue colonies or colonies with deep light blue centers.
(4) Drinking water is usually disinfected by chlorine, and the water contains a certain amount of residual chlorine, which makes the coliforms in a state of destruction or inhibition. When collecting water samples, sodium thiosulfate should be added for dechlorination, so that the destroyed bacteria can be revived and repaired, thus avoiding the appearance of low or even false negative counting results.
(5) It is very important to preserve water samples correctly after sampling. If it is not preserved properly, the coliforms in the sample will die or grow again under certain conditions, which will affect the accuracy of the test results. After receiving the water sample, the inspection room shall conduct inspection immediately. If it cannot be inspected for some reason, it should be put into the refrigerator immediately and inspected within 2 hours.
Regarding the influence of storage time and temperature of water samples on the number of coliform bacteria, Lonsans and others reported that when the number of coliform bacteria in water samples is small, there is little difference between refrigerator storage and room temperature storage; If there are a large number of bacteria in water samples, the number of bacteria will decrease faster when stored at room temperature (23-39.5℃) than when stored in refrigerator (0- 1O℃).
Water quality fecal coliform detector
JMS2009 online fast coliform monitor can quickly detect many common fungi in life, such as Escherichia coli, total coliform, fecal coliform and total fecal coliform.
Instrument characteristics
automatic detection
The operation is simple, and the field test can be carried out without complicated and expensive laboratory equipment and professionals.
Automatic sampling frequency can be programmed: from once every hour to once every 24 hours.
The detection period is short, less than 12 hour (fast analysis speed).
Continuous detection of Qualcomm quantity
Real-time, online and automatic detection.
Multiple output function
Fecal coliform detector
Measuring principle
FC medium is most suitable for the growth of coliform bacteria and fecal flora.
In microbial culture medium, Escherichia coli and fecal Escherichia coli contain specific
Sex enzyme, the substrate used in this system can be decomposed and released by this specific enzyme.
Produce a compound to change the color of the culture medium. This system is universal.
Detect the color change of the culture medium and detect the coliforms in the water.
Fecal Escherichia coli. FC culture solution is a patented product.
applied range
Is suitable for coliforms such as drinking water, surface water, underground water, sewage and the like,
Automatic monitoring of fecal coliforms.
Sample analysis method
Inject water samples into FC culture solution and culture bacteria at a certain temperature.
(coliforms need to be kept at a constant temperature of 36.5℃, and fecal coliforms need to be kept at a constant temperature of 44.5℃). through
The coliforms and fecal coliforms in water samples were detected by continuous photometric determination.
After measuring each sample, the instrument will automatically sterilize the pipeline.
technical parameter
Sampling amount:1.5l.
Detection limit: 1 piece/100ml.
Sampling frequency: 1 hour (adjustable)
Measurement period: the longest is 12 hours.
Detection time: less than 12 hours.
Culture temperature: 36.5℃ or 44.5℃
Disinfection of pipelines: before each measurement and after pollution.
Pipeline cleaning: after each pipeline disinfection.
Reagent: culture medium: 1 bottle/sample.
Sodium hypochlorite (available chlorine: 0.5%): 5l a week.
Zero correction: automatic correction before each injection.
Reference solution: culture solution
Communication interface: RS232 or 485
Alarm signal: controller failure, temperature failure, microprocessing.
Fault, instrument fault
Remote control: remote control of startup and standby.
Environment: moistureproof and dustproof, temperature 0 ~ 40℃
Power supply: 220v AC/50hz.
Protection grade: IP55
External dimensions:
Weight: 100kg