Which one is not a biofertilizer

Options

A. Azotobacter
B. Azolla
C. Bacillus thuringiensis
D. Clostridium

Answer

To determine which option is not a biofertilizer, we will analyze each of the provided options step by step.

### Step 1: Analyze Azobacter
- **Description**: Azobacter is a genus of free-living nitrogen-fixing bacteria found in neutral and alkaline soils.
- **Function**: It helps in fixing atmospheric nitrogen, making it available to plants.
- **Conclusion**: Azobacter is a biofertilizer.

### Step 2: Analyze Azolla
- **Description**: Azolla is an aquatic fern that forms a symbiotic relationship with nitrogen-fixing blue-green algae.
- **Function**: It enhances soil fertility by fixing nitrogen.
- **Conclusion**: Azolla is a biofertilizer.

### Step 3: Analyze Clostridium
- **Description**: Clostridium is a genus of bacteria that can fix nitrogen.
- **Function**: Some species are known to contribute to soil fertility by fixing atmospheric nitrogen.
- **Conclusion**: Clostridium is a biofertilizer.

### Step 4: Analyze Bacillus thuringiensis
- **Description**: Bacillus thuringiensis (Bt) is a bacterium known for its insecticidal properties.
- **Function**: It is primarily used to produce insect-resistant plants by generating the Bt toxin.
- **Conclusion**: Bacillus thuringiensis is not a biofertilizer.

### Final Answer
The option that is not a biofertilizer is **Bacillus thuringiensis**.

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