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What is TSIA used for?
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A differential medium for the identification and fermenation of gram - enteric bateria based on their ability to ferment selected carbs and to produce hydrogen sulfide
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What does the TSIA medium contain?
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3 sugars, pH indicator, 2 sources of sulfer, an iron salt and a general nutrient base like peptone or yeast extract
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What are the sugars in TSIA?
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Glucose 0.1%, sucrose 1% and lactose at 1%
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What it the pH indicator?
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Phenol red
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What color is phenol red at neutral pH values?
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Red
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What color is phenol red in acidic conditions?
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Yellow
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What color is phenol red in alkaline conditions?
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Bright red
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What is Cysteine in this medium?
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Sulfur-containing amino acid
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What is Thiosulfate in this medium?
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Sulfur source
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Besides Sulfur sources what else do Cysteine and Thiosulfate serve as?
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Electron acceptors
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Why is the iron salt necessary?
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To detect the producation of Hydrogen sulfide gas resulting from the utilization of these sulfur sources
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Unlike the phenol red carbohydrate broth tubes that only contained a single sugar, what is in each of the TSIA tubes?
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3 sugars-glucose, lactose and sucrose
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What is 10 times lower than the concentrations of either lactose or sucrose?
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Glucose
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What do organisms usually utilize first?
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Glucose, after about 10 hours of incubation
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After the utilization of glucose, what does the organism use?
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Metabolism of sucrose, lactose or peptone
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