24. If you had been growing a mixture of bacteria on a mediun containing gelatin

Question

24. If you had been growing a mixture of bacteria on a mediun containing gelatin as a solidifying agent and notices, after incubation, that the medium haá turned to a liquid even at cool temperatures, you could assume that: by the organisns A. The gelatin had been used as nutrient by the organisms B. The medium was unsuitable for growth of the org C. The organisms had used the medium for growth but not the D. The gelatin in the medium was broken down by the incuba- B. None of these are true since this is the usual or expected gelatin. tion temperature. result. 25. The name of the chemical reagent used to detect the presence of indole in a culture tube is which of the following: A. Methy red indicator B. Potassium hydroxide solution C. Alpha naphthol D. Kovac's reagent E. Nessler's reagent 26. Indole is formed by the action of some bacteria on: A. Proteins B. Lactose c. Gelatin D. Giucose E. Tryptophan 27. The blacking of triple sugar iron agar (or pepton-iron agar) is due to the interaction of Hs and: A. Glucose B. Gelatin C. FeSO D. Red blood cells E. Iron 28. The number of different kinds of carbohydrates present in a fermentation broth test is always: A. 1 B. 2 D. more than 3 E. None 29. The actual change being tested for in the VP test is which of the following: A. Sharp lowering of the pH of the medium B. The production of acetylmethyl carbinol C. The oxidation of glucose D. The production of ammonia B. The production of vinyl pyrrole

Explanation / Answer

24. A. The gelatin had been used as a nutrient by the organisms.

This test can be used to detect gelatin hydrolysing bacteria. If they are present, the media turns liquid and cannot be solidified back even at low temperatures.

25. Kovac's reagent (used in Indole detection test).

26. Tryptophan

27. Iron

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