Which type of pH conditions are required for action by Bt toxin?

Options

A. 8.6
B. 1
C. 7
D. 6.8

Answer

**Step-by-Step Solution:**

1. **Understanding Bt Toxin**: Bt toxin is produced by the bacterium Bacillus thuringiensis, which is a Gram-positive, spore-forming bacterium. The toxin is known for its insecticidal properties.

2. **Nature of Cry Toxins**: The toxins produced by Bt are known as Cry toxins. These toxins are synthesized in the form of inactive protoxins.

3. **Activation of Cry Toxins**: For the Cry toxins to become active and exert their insecticidal effect, they need to be activated. This activation occurs in the presence of alkaline (high pH) conditions.

4. **Role of Insect Gut**: When an insect ingests the Bt toxin, the alkaline environment of the insect's gut (which is typically higher than pH 7) solubilizes the inactive Cry crystals, converting them into their active form.

5. **Identifying pH Conditions**: The question provides several pH options: 8.6, 7, and 6.8. Among these:
- pH 8.6 is alkaline.
- pH 7 is neutral.
- pH 6.8 is slightly acidic.

6. **Conclusion**: Since the activation of Bt toxin requires alkaline conditions, the only suitable option from the given choices is pH 8.6. Therefore, the correct answer is 8.6.

**Final Answer**: The type of pH condition required for the action of Bt toxin is **8.6**.

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