Sierra College Department of Biological Sciences

Microbiology Diagnostic Tests: Sulfur Indole Motility (SIM) Medium

The SIM medium can be used to show three different features of bacteria. Two of these are visible upon inspection of the inoculated medium after 24 hours of incubation, and the third requires that 10-12 drops of a liquid reagent be applied to the surface of the medium.


-------A ---------------------B-------------------C-------

1. Which of these tubes contains organisms that are capable of producing hydrogen sulfide?

2. What type of organic compound is being degraded by the bacteria producing the hydrogen sulfide?

3. What is the name of the black precipitate present in tube C?

4. The liquid (reagent) visible on the surface of tubes B and C was used to test for a nitrogen containing compound called what? Which tube contains organisms that can form this substance?

5. What is the name of the test reagent (liquid) used in tubes B and C? Organisms that test positive with this reagent are capable of catabolizing what?

6. Which of the three tubes contains organisms that are not motile? How do you know?

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