BeNa Culture Collection
|Culture medium||Nutritional gravy medium (English name: NA/NB): beef paste 3.0g, peptone 10.0g,NaCl 5.0g, agar 20.0g (not included in liquid medium), distilled water 1.0L,pH 7.0. Sterilization at 121 ℃ for 15min. [Note] Adding 5 mgMnSO4 · H2O to culture Bacillus is beneficial to produce spores.|
|Subculture procedure||① Positive quality control bacteria: BNCC269342 ATCC25922; (2) negative quality control bacteria: none; (3) Activate and increase bacteria according to the above quality control samples, so that the absorbance of the diluent ten times of the two bacteria is in the range of 0.3~0.5; (4) Mix the two original bacteria liquid in the same volume, dilute 25,000 times, absorb 0.5mL of final diluent and put into 10mL of protective agent (quantitative bacteria protective agent), and mix well; (5) Dividing the mixed liquid into 0.4mL/Xilin bottles, pre-freezing at -80 degrees Celsius for 20-24 hours, taking out freeze-drying overnight, sealing the freeze-dried quality control products and labeling them for storage the next day;|
|Growth conditions||37 ℃, aerobic, 18-24h|
|Storage conditions||-20 ℃, kept away from light|
|application||Sensitive test; Antibacterial test; Food testing; Cosmetic testing; Culture control; Quality control strain; API verification bacteria, GB 4789.38-2012 Escherichia coli count positive control strain.|
|Sharing mode||Public welfare sharing|
Reference material of Escherichia coli Count in food
Product number: 359092
Date of setting value: June 15, 2021
Escherichia coli is a food-borne microorganism that grows in the intestines of humans and animals, and is also an important indicator of fecal contamination. The number of E. coli bacteria indicates the degree of food contamination by feces, and also reflects the harm to human health. Therefore, almost all food microbiological inspection standards will use the E. coli count limit index as an important hygienic index. This reference material has a wide range of uses in microbiological laboratory proficiency verification, evaluation of microbiological measurement methods and instrument calibration, and evaluation of growth rate of microbiological culture medium, and provides metrological traceability guarantee for food safety and microbiological testing
1. Sample preparation
Selected Escherichia coli(ATCC 25922) as the raw material,After culturing, the bacterial suspension was dispensed into vials with a pipette, and the lids were sealed after lyophilization.
2. Traceability and value setting method
The reference material is determined by multiple organizations using the spreading method. After 10 times series dilution of the standard substance, the number of colonies on the medium plate is counted, and the total number of colonies is calculated by formula, and the unit of measure is CFU/mL(CFU, colony forming unit Colony-Forming Units). By using quality volume etc measurement instruments that is verified and calibrated, and the quantitative measurement methods which meet the requirements of metrology characteristics, it is ensured that the measurement value of this reference material can be traced back to the basic unit of entity number “1” and the national legal unit of measurement “L”.
3. Characteristic value and uncertainty
|No.||name||standard value (CFU/mL)||Extended uncertainty (CFU/mL,k = 2)|
|BNCC 359092||Escherichia coli Counting Standards in Foods||1.2×104||0.2×104|
The uncertainty of the setting value is obtained by the combination of uncertainty components introduced by the setting method, balance, pipette, dilution factor, uniformity and stability.
4. Uniformity and stability evaluation
According to the JJF1343 national metrology technical specifications (equivalent ISO guide 35), use Escherichia coli pour plate method and evaluate the uniformity of the sample according to the principle of random sampling. The results of variance analysis show that the uniformity of the sample is good; Using the same measurement method, the stability of the sample is evaluated according to the principle of first density and then sparse. The trend analysis results show that it can be stored stably for a long time at -20 ℃, for 7 days at 4 ℃ and can be transported in ice packs.The reference material is valid for 12 months from the setting date. We will continue to track and monitor the stability of the standard substance. If changes in the value are found during the validity period, the user will be notified in time.
5.Packaging, storage and usage
1. packaging and preservation: the reference material is packed in 3ml penile bottles and sealed after freeze-drying. It is shipped on dry ice. Upon receipt, check if the dry ice is exhausted or not. Then put it in a refrigerator at -20 ℃.
2. use: the reference material should be used up at one time after opening the bottle. Before use, take it out of -20 ℃ and balance it at room temperature for 10 minutes. Use a pipette to accurately measure 1.0mL(20 ℃) of sterile distilled water to re-dissolve the freeze-dried reference material.
3. the reference material contains microorganisms. masks and latex gloves should be worn before handling. Pay attention to protect yourself during the handling, avoid inhalation or direct skin contact. After use, the remaining samples, packaging bottles, sampling tips and other consumables should be autoclaved according to biological pollution waste.
GB4789.38—2012 National Food Safety Standard Food Microbiological Inspection Escherichia coli Count [S].
1. the reference material is only for laboratory research and analysis and testing. Complaints arising from improper use or storage by users shall not be liable.
2. Please check the variety, quantity, packaging and certificate immediately upon receipt. The relevant compensation is limited to the reference material itself and does not involve any other losses.
3. the reference material is shipped with the certificate stamped”"special seal for certified reference materials of Beijing Beina Chuanglian Biotechnology Research Institute". We will not accept any complaints if the certificate can not be provided. Please keep this certificate properly.
4. For more application-related information, please contact the technical department.
Beijing Beina Chuanglian Biotechnology Research Institute