Which of the following microorganisms is used as a biofertiliser

Options

A. Bacillus
B. Azospirillum
C. Pseudomonas
D. Saccharomyces

Answer

To determine which microorganism is used as a biofertilizer, we can analyze the given options step by step.

### Step-by-Step Solution:

1. **Understanding 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. They are essential in organic farming to enhance soil fertility.

2. **Analyzing the Options**:
- **Option 1: Bacillus**
- Bacillus thuringiensis is a well-known bacterium that produces a toxin harmful to certain insects. It is primarily used as a bio-insecticide, not a biofertilizer. Therefore, this option is not correct.

- **Option 2: Azospirillum**
- Azospirillum is a nitrogen-fixing bacterium. It helps in fixing atmospheric nitrogen into a form that plants can use, thereby enhancing soil fertility. This characteristic makes it a biofertilizer. Hence, this option is correct.

- **Option 3: Pseudomonas**
- Pseudomonas species are often involved in bioremediation processes, such as cleaning up oil spills. They do not function as biofertilizers, so this option is incorrect.

- **Option 4: Saccharomyces**
- Saccharomyces is a genus of yeast used in baking and brewing industries. It does not contribute to soil fertility as a biofertilizer, making this option incorrect.

3. **Conclusion**:
- Based on the analysis, the only microorganism listed that acts as a biofertilizer is **Azospirillum**.

### Final Answer:
**Azospirillum** is the microorganism used as a biofertilizer.

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