Which one of the following is not used as biofertiliser ?

Options

A. Bacillus thuringiensis
B. Anabaena
C. Nostoc
D. Rhizobium

Explanation

### Step-by-Step Solution:

1. **Understanding Biofertilizers**:
- Biofertilizers are substances that contain living microorganisms or latent cells. They enhance the nutrient availability to plants when applied to seeds, plant surfaces, or soil by colonizing the rhizosphere.

2. **Identifying the Options**:
- The options provided are:
- A) Bacillus thuringiensis
- B) Anabina
- C) Nostoc
- D) Rhizobium

3. **Analyzing Each Option**:
- **Bacillus thuringiensis**: This bacterium is primarily used in genetic engineering to create transgenic plants, such as Bt cotton, which produces a toxin to protect against pests. It is not used as a biofertilizer.
- **Anabina**: This is a nitrogen-fixing cyanobacterium that is used as a biofertilizer.
- **Nostoc**: Another nitrogen-fixing cyanobacterium that serves as a biofertilizer.
- **Rhizobium**: This bacterium forms symbiotic relationships with legumes and is well-known for its role in nitrogen fixation, making it a biofertilizer.

4. **Conclusion**:
- Among the options, **Bacillus thuringiensis** is the only one that is not used as a biofertilizer, as it is utilized for creating transgenic plants.

5. **Final Answer**:
- The correct answer is **A) Bacillus thuringiensis**.