| Customization: | Available |
|---|---|
| CAS No.: | 3 Years |
| Formula: | Culture Medium |
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CRM002 E.coli Chromogenic Medium
(Chromogenic E.coli Agar)
For the rapid detection and enumeration of Escherichia coli.
Peptone and yeast extract powder provides carbon and nitrogen sources and trace elements; sodium chloride maintains osmotic equilibrium; agar as medium coagulant; dodecyl sulfate inhibit Gram-positive bacteria; chromogenic substrate and large intestine coli β- glucuronidase enzyme specific reaction, hydrolysis of the substrate, the release of the color groups produce green colonies on the light yellow plate.
Formulation (per liter):
Peptone :15.0g
Yeast extract powder: 3.0g
Sodium chloride: 5.0g
Sodium lauryl sulfate:0.1g
Agar: 12.0g
Chromogenic substrate 6.5g
Final pH 7.0 ± 0.2
1. Weigh 41.6g of the product, adding 1.0L distilled or deionized water, heated to boiling stirring until completely dissolved, dispensing into flask, 115 autoclaved for 10minutes.
2. Take 25.0g or 25.0ml of sample with sterile procedures , added to the flask containing 225.0mL of sterile phosphate buffered saline (or saline) , shaken thoroughly homogenized with a homogenizer or a 1:10 dilution of 1min solution, diluted 1:10 and then continue to select the appropriate serial dilutions of three, the two plates inoculated with each dilution, poured dissolved by heating and cooled to about 45 medium.
3, observe the results.
Quality Control
This product appears light yellow after the pouring on plate, these strains were inoculated after 36 ± 1 18 ~ 24h culture growth in the following table.
Bacteria name bacteria NO. growth situation feature
Escherichia coli ATCC25922 good green colonies
Citrobacter ATCC8090 good colorless colonies
Salmonella typhimurium CMCC50115 good colorless colonies
Enterococcus faecalis ATCC29212 suppressed -----
Storage: Store in a dark, cool and dry place, tighten the caps immediately after use. Storage period of two years.
Specifications: Configurable 1L medium dry.
Package: Packing material:Packed in plastic bottles with plastic film wrapped
Capacity:1liter/bottle
1.Offering Free Sample for Testing .
2.R & D team to provide technical support.
3.Provide packaging, labeling OEM customization.
Q1:
Sometimes color of dehydrated culture media between batches have subtle differences,would this affect test results?
A1:The source and storage conditions of raw material is different ,so there may be a slight difference in color, which is a normal phenomenon. Products from our company have to undergo a rigorous inspection and sensory biology verification before sale, to ensure that all the indicators characteristics of the product is under enterprise standard to the extent permitted, not affect the test results.
Q2:
After pouring the liquid medium on the plate , medium seems hard to clot or coagulation time is longer, is it some problem with product quality?
A2: The reason may be:
The required hydration in the preparation process have not been done completely .That is to say distilled water is not boil sufficiently to dissolve agar. Because agar proportion, easily settle in the bottom of the bottle, if not fully shaken after high-temperature sterilization, it will lead to uneven upper agar culture gene content and difficult to set.
Q3:
Why some colonies of E. coli chromogenic medium color not shown above, but also confirmed through biochemical tests for E. coli (false negative)?
A3: E. CHROMOGENIC medium is based on the principle of specific enzyme of E. coli and design, 94% of E. coli have β- glucuronidase enzyme, with the chromogenic enzyme substrate medium role in the formation of blue-green colonies. And about 4% of the E. coli does not have β- glucuronidase enzymes, including concern O157: H7 Escherichia coli. Therefore, these E. coli can not be displayed on the color characteristic of E. coli chromogenic medium,it is possible of false-negative on the chromogenic medium. However, the traditional medium of the same can not avoid the problem of false negatives, such as: no gas or slow ferment lactose intolerance may also strain 44.5 false negatives in the conventional medium. For this small part of the E. coli can be detected using other methods.
Q4:
During anaerobic or micro-aerobic culture, is it necessary to remove gas bag from package? How to use oxygen indicator?
A4: During anaerobic or micro-aerobic culture, using method of gassing agent should be done according to the manufacturer's instructions. Remove the paper bag from the plastic packaging, but do not cut the paper bag. Torn the outer packaging of oxygen indicator then it can be used.
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