A urease test is used to identify Mycobacterium tuberculosis because:

• A. it ferments lactose, resulting in acid production
• B. it reduces nitrate to nitrite
• C. it forms endospores under adverse conditions
• D. it produces the enzyme urease, which hydrolyzes urea to ammonia and carbon dioxide

Answer: (D)

Verified step by step guidance

1. Understand the purpose of the urease test: it detects the presence of the enzyme urease, which hydrolyzes urea into ammonia and carbon dioxide.
2. Recall that Mycobacterium tuberculosis produces urease, which is why the urease test can be used to identify it.
3. Recognize that the other options (fermentation of lactose, nitrate reduction, endospore formation) are unrelated to the urease test and Mycobacterium tuberculosis identification.
4. Know the chemical reaction catalyzed by urease: \(\text{urea} + \text{H}_2\text{O} \xrightarrow{urease} 2 \text{NH}_3 + \text{CO}_2\).
5. Understand that the production of ammonia increases the pH, which can be detected by a color change in the test medium, confirming urease activity.