Which of these processes of the nitrogen cycle can be performed by anaerobic bacteria?

Options

A. Nitrification
B. Denitrification
C. Ammonification
D. Nitrogen fixation

Answer

**Step-by-Step Solution:**

1. **Understanding Anaerobic Bacteria**: Anaerobic bacteria are microorganisms that do not require oxygen for their growth and can survive in environments devoid of oxygen.

2. **Identifying the Processes**: The processes of the nitrogen cycle mentioned in the question are:
- Nitrification
- Denitrification
- Ammonification
- Nitrogen fixation

3. **Analyzing Each Process**:
- **Nitrification**: This process involves the conversion of ammonia into nitrates and requires oxygen, thus it cannot be performed by anaerobic bacteria.
- **Denitrification**: This is the process where nitrates in the soil are converted into nitrogen gas, which can occur in the absence of oxygen. This process is specifically carried out by anaerobic bacteria.
- **Ammonification**: This process involves the conversion of organic nitrogen into ammonia. While some anaerobic bacteria can participate, it is not exclusively performed by them.
- **Nitrogen Fixation**: This process, which converts atmospheric nitrogen into ammonia, is primarily carried out by certain bacteria, some of which are anaerobic, but many nitrogen-fixing bacteria require oxygen.

4. **Conclusion**: Among the processes listed, denitrification is the one that can be performed exclusively by anaerobic bacteria.

5. **Final Answer**: The correct answer is **Denitrification**.

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