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Principle
- TCBS agar is composed of yeast extract, protease peptone, sodium citrate, sodium thiosulfate, ox gall, saccharose, sodium chloride, ferric citrate, bromothymol blue, thymol blue, and agar. Yeast extract provides nitrogen, carbon, vitamins and other growth factors and protease peptone provides the nitrogen and amino acids. Sodium citrate, sodium thiosulfate, and oxgall are selective agents to inhibit gram-positive organisms and suppress coliforms in addition to that increase the pH of the medium.
- The alkaline pH of the medium enhances the growth of Vibrio cholerae. Saccharose is a fermentable carbohydrate. Sodium chloride maintains osmatic balance. Sodium Thiosulfate is a sulfur source and reacts with ferric citrate as an indicator to detect hydrogen sulfide production. Bromthymol blue and thymol blue are pH indicators. Agar is a solidifying agent.
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