Which one acts as a biofertilizer

Options

A. E. coli
B. Yeast
C. Rhizobium
D. Chlamydomonas

Answer

To determine which organism acts as a biofertilizer among the given options (E. coli, yeast, rhizobium, and chlamydomonas), we can follow these steps:

### Step-by-Step Solution:

1. **Define Biofertilizers**:
- Biofertilizers are substances that contain living microorganisms which promote plant growth by increasing the supply or availability of primary nutrients to the host plant.

2. **Identify the Role of Microorganisms**:
- These microorganisms can enhance soil fertility by fixing atmospheric nitrogen, decomposing organic matter, and making nutrients more available to plants.

3. **Evaluate the Options**:
- **E. coli**: This bacterium is primarily known for its role in the human gut and does not contribute to soil fertility or plant growth.
- **Yeast**: While yeast is useful in fermentation processes, it does not function as a biofertilizer.
- **Chlamydomonas**: This is a green algae, which can contribute to some extent in nutrient cycling but is not primarily recognized as a biofertilizer.
- **Rhizobium**: This is a genus of bacteria that forms symbiotic relationships with legumes, fixing nitrogen from the atmosphere and enriching the soil, making it a well-known biofertilizer.

4. **Conclusion**:
- Based on the definitions and roles of the microorganisms, **Rhizobium** is the only organism among the options that acts as a biofertilizer.

### Final Answer:
- The correct answer is **Rhizobium**.

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