Which one of the following bacteria has potential for nitrogen fixation

Options

A. Nitrosomonas
B. Nitrobacter
C. Nitrosococcus
D. Rhizobium

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks which bacteria has the potential for nitrogen fixation among the given options: Nitrosomonas, Nitrobacter, Nitrosococcus, and Rhizobium.

2. **Understand Nitrogen Fixation**: Nitrogen fixation is the process by which certain bacteria convert atmospheric nitrogen (N₂) into ammonia (NH₃), which can then be used by plants.

3. **Analyze the Options**:
- **Nitrosomonas**: This bacterium is known for oxidizing ammonia into nitrite. It does not fix nitrogen.
- **Nitrobacter**: This bacterium oxidizes nitrite into nitrate, playing a role in the nitrogen cycle but not in nitrogen fixation.
- **Nitrosococcus**: Similar to Nitrosomonas, it is involved in the oxidation of ammonia to nitrite and does not fix nitrogen.
- **Rhizobium**: This bacterium forms a symbiotic relationship with leguminous plants and is known for its ability to fix atmospheric nitrogen into a form usable by plants.

4. **Conclusion**: Based on the analysis, Rhizobium is the only bacterium among the options that has the potential for nitrogen fixation.

5. **Final Answer**: The correct answer is **option D: Rhizobium**.

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