Soil microorganism which converts proteins to ammonia is :

Options

A. Bacillus vulgaris
B. Nitrosomonas
C. Pseudomonas
D. None of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a soil microorganism that converts proteins into ammonia. This process is crucial in the nitrogen cycle and is known as ammonification.

2. **Identifying the Process**: The conversion of proteins to ammonia is carried out by specific bacteria known as ammonifying bacteria. These bacteria break down organic matter, including proteins, into simpler compounds, ultimately resulting in ammonia (NH3).

3. **Identifying the Correct Bacteria**: Among the various soil microorganisms, one of the key players in the process of ammonification is *Bacillus vulgaris*. This bacterium is known for its ability to decompose organic matter and convert proteins into ammonia.

4. **Eliminating Other Options**:
- **Nitrosomonas**: This is a nitrifying bacterium that converts ammonia into nitrites, not proteins into ammonia. Therefore, it is not the correct answer.
- **Pseudomonas**: Although this is a nitrogen-fixing bacterium, it primarily converts atmospheric nitrogen into ammonia, rather than converting proteins into ammonia. Thus, it is also not the correct answer.

5. **Conclusion**: Based on the information provided, the soil microorganism that converts proteins to ammonia is *Bacillus vulgaris*.

**Final Answer**: *Bacillus vulgaris*

---