2 In clinical applications of this test system, reagents are added only if the glucose (oxidation/fermentation) test result is yellow or at least three other tests are positive. If these conditions are not met, a MacConkey agar plate is streaked and additional tests are performed confirming glucose metabolism, nitrate reduction, and motility. Why do you think this is so? Be specific. 3 Suppose, after 24 hours incubation, you notice no growth in the tubes containing mineral oil. Assuming that it is behaving properly under these conditions, what do you know about the organism and what predictions can you safely make about its performance in the decarboxylase tests, fermentation tests, and nitrate reduction test? Is it a member of Enterobacteriaceae?
Added by Karen G.
Close
Step 1
In the given clinical test system, reagents are added only if the glucose (oxidation/fermentation) test result is yellow or at least three other tests are positive. This is likely because the yellow color indicates a positive result for glucose metabolism, which Show more…
Show all steps
Your feedback will help us improve your experience
Madhur L and 65 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Methyl Red: This test determines the presence of acidic byproducts of glucose fermentation, specifically mixed acid fermentation. The test organism is inoculated into a tube of MRVP broth (Methyl Red, Voges-Proskauer broth), allowed to grow, and then tested for pH below 4.4 by adding the pH indicator Methyl Red. A bright red color indicates a positive result (pH below 4.4), whereas a negative result shows yellow (pH above 4.4). Voges-Proskauer: This test determines the ability of bacteria to produce acidic byproducts from glucose, specifically the presence of acetoin, an intermediate of 2,3 butanedio fermentation. The test organism is inoculated into a tube of MRVP broth, allowed to grow, and then tested for the presence of acetoin by adding 10 drops each of alpha naphthol and 40% KOH. A dull brick red color indicates a positive result. This result may require vigorous agitation and application of heat (placing the tube in the incubator) and may take up to 1 hour to develop. No change in the color of the tube indicates a negative result.
Dominador T.
When grown on urea agar, the control organism used on lab #9, turned the medium pink due to the accumulation of ammonia. To detect the presence of oxidase, an enzyme needed for aerobic respiration, an artificial acceptor is used that changes purple if positive. To detect the presence of phenylalanine deaminase, drops of should be added to the tube, resulting in a green precipitate. The control organism for the lipase test was . A halo was observed around it indicating the breakdown of olive oil in the medium. If an organism is positive for the mixed acid test, it is most likely negative for the test. In the nitrate reduction test, the control organism, , is able to reduce nitrates into nitrites. The medium used to detect the presence of proteases was The medium used to detect the presence of amylase was The medium used to detect the presence of lipases was To detect the presence of catalase, drops of should be added to a slide containing the organism in question and the presence of oxygen bubbles should be detected if the enzyme is presence.
Adi S.
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
Watch the video solution with this free unlock.
EMAIL
PASSWORD