Cry-gene which synthesize crystal protein isolated from:

Options

A. Bacillus thuringiensis
B. Rhizobium
C. Bacillus polymyxa
D. Clostridium

Answer

**Step-by-Step Solution:**

1. **Understanding the Cry-gene**: The cry-gene, also known as the Bt gene or Bt toxin, is associated with the production of crystal proteins that are toxic to certain insects.

2. **Identifying the Source**: The question asks from which organism the cry-gene is isolated. We need to identify the correct bacterium from the given options.

3. **Evaluating the Options**:
- **Option 1: Bacillus thuringiensis**: This bacterium is known for producing Bt toxin, which is a crystal protein toxic to insects.
- **Option 2: Rhizobium**: This is primarily known for its role in nitrogen fixation in legumes, not for producing cry-proteins.
- **Option 3: Bacillus polymyxa**: This bacterium is known for its role in soil health and plant growth but does not produce cry proteins.
- **Option 4: Clostridium**: This genus includes bacteria that are primarily known for their role in fermentation and some pathogenic species, not for producing cry proteins.

4. **Conclusion**: Based on the information, the cry-gene that synthesizes crystal proteins is isolated from **Bacillus thuringiensis**. Therefore, the correct answer is **Option 1**.

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