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Citrate Lab Report

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CITRATE TEST: Citrate was the carbon source of this medium. If an organism used the enzyme citrate permease, the medium became basic due to its utilization for fermentation of carbohydrates. The medium started out green and turned blue, indicating a positive test due to hydrolyzation of citrate into oxaloacetate and acetate using the enzyme citrate lyase. If growth was apparent but lacked a color change, it was a positive result. Acid = (green & negative) and base = (blue & positive) Growth = (positive). A negative tube showed no growth5. The citrate test identified a functional citric acid cycle in which facultative anaerobes utilized. Ingredients in the medium included: 1) A indicator dye called Bromthymol blue, which turned green when acids were present5 2) A nitrogen source, ammonium salts in order to test the ability of an organism to use a single specific carbon source5 SIM MEDIA This procedure began with …show more content…

The medium had a pH indicator called phenol red and a potassium phosphate buffer that was used to resist alkalization of the medium from peptone metabolism. When the pH level elevated, rapid urease positive organisms turned a bright pink and orange or yellow colors indicated a negative result for urea hydrolysis. PHENYLALANINE Deaminase Test: This test looked for the enzyme, phenylalanine deaminase, which removed an NH2 group from cysteine to produce pyruvic acid, ammonia, and hydrogen sulfide. Next, five drops of ferric chloride was added to the tube. A positive test would turn a green color due to the reaction phenylpyruvic acid with the reagent, ferric chloride. A negative test stayed a yellow color indicating the absence of phenylalanine deaminase. 5 NITRATE REDUCTION TEST: When nitrate (NO3) is oxidized, it has been reduced to nitrite (NO2). If the unknown organism had the enzyme nitrate reductase, it reduced nitrate shown

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