Description of MM0283
Bismuth Sulphite Agar
Use and description: Bismuth sulphite agar is a selective medium used to isolate Salmonella typhi and other enteric bacilli. Brilliant green and bismuth sulphite make this medium highly selective. Salmonella produces hydrogen sulphide in the medium which reduces ferrous sulphate around the colonies and produces a metallic precipitate. Salmonella typhi appears as flat, black colonies surraunded by a zone of black with metallic sheen.
Composition per liter: Powder A: Agar………………….……………………...15.000 g Peptone……………………….……………..17.000 g Brilliant green………………………………...0.016 g Ferrous citrate…………………………….......0.003 g Powder B: Bismuth sulphite……………………………..8.000 g Glucose……………………………….……...5.000 g Disodium hydrogen phosphate………………4.000 g
Final pH of the ready to use medium: 7.6 ± 0.2
Medium preparation: Add 32 grams of Powder A to 1 liter of distilled water. Mix thoroughly and heat with frequent agitation. Sterilise for 15 minutes at 121°C. Cool to 45 to 50oC. Suspend 17 grams of Powder B in 100 ml of deionised water, heat gently with stirring until the medium has just begins to boil, simmer for 30 seconds and cool quickly. Mix prepared Powder A and B together and pour into sterile Petri dishes while gently shaking flask to disperse the precipitate. Store the plates 3 days before use. Use within 7 days.
Quality specifications: Dehydrated medium: homogeneous, greenish-beige fine powder. Ready to use medium: green-beige agar, slightly opalescent.
Microbiological response:
Storage: Dehydrated medium should be stored between 10 to 25oC. Once opened, place the container in a dark, dry place. The dehydrated medium should not be used if there is any lump or the color has changed from the original. |
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