Final answer:
The medium used to assess urease activity in bacteria is urease broth, which includes urea, buffers, a tiny amount of nutrients, and phenol red as a pH indicator.
Step-by-step explanation:
The medium used to test for urease activity is known as urease broth. This specialized medium contains urea, buffers, minimal nutrients, and the pH indicator phenol red. During the test, bacteria are inoculated into the urease broth and then incubated.
If the bacteria produce urease rapidly, they hydrolyze the urea in the broth to ammonia, which raises the pH and changes the color of the phenol red indicator to deep pink, indicating a positive test result. This color change is a direct consequence of the enzymatic activity converting urea into ammonia (NH3) and carbon dioxide (CO2).