Select the odd microbe from the following options by considering its role in nitrogen cycle.

Options

A. Clostridium
B. Nostoc
C. E.coli
D. Rhizobium

Answer

To solve the question of selecting the odd microbe based on its role in the nitrogen cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Nitrogen Cycle**: The nitrogen cycle involves several processes including nitrogen fixation, nitrification, and denitrification. Different microbes play specific roles in these processes.

2. **Identify the Microbes**: The options provided are:
- Clostridium
- Nostoc
- E. coli
- Rhizobium

3. **Analyze Each Microbe's Role**:
- **Clostridium**: This is a nitrogen-fixing bacterium that converts atmospheric nitrogen into ammonia.
- **Nostoc**: This is a cyanobacterium that also plays a role in nitrogen fixation.
- **Rhizobium**: This bacterium forms a symbiotic relationship with legumes to fix nitrogen.
- **E. coli**: This bacterium is primarily known for its role in the gut and does not participate in the nitrogen cycle.

4. **Determine the Odd One Out**:
- Clostridium, Nostoc, and Rhizobium all play roles in nitrogen fixation, while E. coli does not contribute to the nitrogen cycle.

5. **Conclusion**: The odd microbe among the options is **E. coli**.

### Final Answer:
The odd microbe is **E. coli**.

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