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12 Cards in this Set
- Front
- Back
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What is the application of the citrate test?
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Used to determine the ability of an organism to use citrate as its sole source of carbon.
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What is in the media of the citrate test?
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Sodium citrate. Ammonium phosphate. Bromthymol blue dye.
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What is the purpose of sodium citrate in the agar?
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It is the sole carbon source. Bacteria that possess citrate-permease can transport the citrate molecules into the cell and produce pyruvate.
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What is the purpose of ammonium phosphate in the agar?
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It is the sole nitrogen source. Bacteria that survive the medium and utilize the citrate also convert the ammonium phosphate to ammonia and ammonium hydroxide which alkalinize the agar to blue.
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What is the purpose to the Bromthymol blue dye?
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pH indicator. Green at pH 6.9 and blue at pH 7.6.
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What is utilization media?
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designed to differentiate organisms based on their ability to grow when an essential nutrient is strictly limited.
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What enzyme is involved in the Citrate test?
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Citrate-Permease. Produce pyruvate from the carbon source citrate.
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Why does the media turn blue?
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Bacteria that can survive the medium and utilize the citrate also convert the ammonium phosphate to ammonia and ammonium hydroxide both of which tend to alkalinize the agar. At pH 7.6 it is blue.
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How do you inoculate and why?
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Lightly inoculated with an inoculating needle rather than a loop to avoid confusion between actual growth and heavy incoulum
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What is the interpretation of a result of a blue citrate slant?
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Citrate is utilized.
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What is the interpretation of a result of no color change and growth in the citrate slant?
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Citrate is utilized.
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What is the interpretation of a result of no color change and no growth in the citrate slant?
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Citrate is not utilized.
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