What medium does a urease test use and what does a positive and a negative test look like, what does this test indicate?
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The urease test typically uses a medium that contains urea, a pH indicator (such as phenol red), and a nutrient source. The most common medium is a urea broth or urea agar. Show more…
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phenol red is the indicator in the urease test and in fermentation tubes fermentation tubes: what color of inoculated medium or negative results? results: color? pH? urease test: what color of inoculated medium or negative results? results: color? pH?
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PART VI: IDENTIFICATION OF GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA Lab Activity (4) UREASE TEST Learning outcomes Explain the biochemical action of the enzyme urease. Explain the results of several bacterial species. Introduction Urea is a metabolic product of protein degradation in microorganisms. Most known bacteria are able to utilize this excreted waste product, while some produce the enzyme urease, which hydrolyzes the carbon-nitrogen bond in urea, resulting in the production of carbon dioxide, water, and ammonia. The presence of this enzyme allows organisms that produce urease to use urea as a nitrogen source. The accumulation of ammonia in the medium containing urea allows for the detection and support of the growth of many urease-producing organisms. The medium supplied contains urea, peptones, and dextrose as a carbon source, as well as a pH indicator (phenol red). The medium appears salmon-orange at neutral pH (pH 6.8). As ammonia accumulates and the pH of the medium rises, the color of the medium changes from salmon-orange to fuchsia. Once the pH reaches 8.4, the change from salmon-orange to fuchsia does not occur, and the pH of the medium remains neutral. Occasionally, acidic products accumulate in the medium, causing the color to change from salmon-orange to yellow. However, this color change is not considered a negative reaction, as it is due to the fermentation of glucose by the organism and not the degradation of urea.
Qualitative analysis of urine Detection of urea 1. In the sodium hypobromite test, why is there a brisk effervescence of nitrogen that appeared in the test tube, thus indicating the presence of urea in the urine sample? 2. In the urease test, why is there a pink or red colored product of the solution, thus indicating the presence of urea in the urine sample?
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