Nitrifying bacteria are

Options

A. Nitrosomonas
B. Thiobacillus
C. Nitrocytis
D. Both (1) & (3)

Answer

**Step-by-Step Solution:**

1. **Understanding Nitrifying Bacteria:**
- Nitrifying bacteria are microorganisms that play a crucial role in the nitrogen cycle, specifically in the process of nitrification.

2. **Defining Nitrification:**
- Nitrification is a two-step biochemical process where ammonia is converted into nitrites and then nitrites are converted into nitrates. This process is essential for soil fertility and plant nutrition.

3. **Identifying the Bacteria Involved:**
- The first step of nitrification involves the conversion of ammonia (NH3) to nitrites (NO2-), which is primarily carried out by the bacterium **Nitrosomonas**.
- The second step involves the conversion of nitrites (NO2-) to nitrates (NO3-), which is performed by the bacterium **Nitrocytis**.

4. **Analyzing the Options:**
- The options given are:
- A) Nitrosomonas
- B) Theobacillus
- C) Nitrocytis
- D) Both A and C
- From our understanding, Nitrosomonas and Nitrocytis are both involved in the nitrification process.

5. **Excluding Incorrect Options:**
- **Theobacillus** is not involved in nitrification; instead, it is associated with the denitrification process, which is the conversion of nitrates back into nitrogen gas, thus completing the nitrogen cycle.

6. **Final Answer:**
- Therefore, the correct answer is **D) Both A and C** (Nitrosomonas and Nitrocytis).

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