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Enterobacter Sakazakii Chromogenic Medium
(Chromogenic Enterbacter Sakazakii Agar)
For the identification and counting of E. sakazakii in infant formula and other foods sample.
Peptone and beef extract powder to provide nitrogen, vitamins, amino acids and carbon; bile salts inhibit Gram-positive bacteria, sodium chloride maintains osmotic equilibrium; agar as medium coagulant; and citric acid, sodium thiosulfate ammonium iron for detecting hydrogen sulfide produced; chromogenic substrate 5-bromo-4-chloro-3-indolyl -ɑ-D-glucoside and the E. sakazakii α- glucosidase reacts, hydrolysis of the substrate , the release of 5-bromo-chloro-3-indolyl color groups to produce yellowish green on the plate - blue-green colonies.
Formulation (per liter):
Soy peptone :5g
Sodium chloride: 5g
Ferric ammonium citrate: 1g
Sodium deoxycholate: 1g
Sodium thiosulfate: 1g
5-bromo-4-chloro-3-indolyl -ɑ-D-glucoside :0.1g
Final pH 7.3 ± 0.2
How to use:
1.Suspend 43.1 g of the product, add 1 L of distilled or deionized water, ,heated to boiling stirring until completely dissolved, dispensing into flask, autoclave at 121 ℃ for 15minutes; cooled to 50 ℃, shake down flat. Can be stored in the refrigerator for a day or stored at room temperature for several days (dark, 4 ℃).
2.Take 333 g of sample and using MPN method taking 100 g, 10 g and 1 g aliquots in 2000ml, 250ml and 100ml Erlenmeyer flasks each of the three, the flask was equipped with a preheat in the warp of 45 ℃ 9/10 (1/10 samples) of sterile distilled water or buffered peptone water, shake cultured at 36 ℃ for 18-22 hours (SN and FDA methods).
3.The suspension was added to 10ml from each equipped 90mlEE broth (022160) / mLST-Vm (022212) in 150mL flasks, culture at 36 ℃ / 44 ℃ for 18-22 hours.
4.Crossed or coating method to mix the broth inoculated onto E. sakazakii chromogenic agar, culture at 35-37 ℃ for 18-24 hours.
5. Use MicrogenTMGN-ID or API20E or biochemical test tube, suspected Enterobacter sakazakii colonies biochemical identification.
This product appears light yellow after pour on plate, these strains were inoculated after 36 ± 1 ℃ cultured for 18-24 hours growth in the following table:
Bacteria name Number of inoculation(cfu/plate) growth situation feature
Enterobacter sakazakii ATCC51329 30 - 300 good Green -Blue Green
Common variant of Bacillus HK7132 30 - 300 good gray-black
Serratia bacteria Serratia HK7121 5000 not long --
Enterococcus faecalis ATCC29212 5000 not long --
Storage: Keep container tightly closed, store in a cool, dry place, away from bright light.
Specifications: Configurable 1L of Medium .