Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because

Options

A. bacteria are resistant to the toxin
B. toxin is immature:
C. toxin is inactive:
D. bacteria encloses toxin in a special sac.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Bt Toxin**: Bt toxin is a protein produced by certain bacteria, notably *Bacillus thuringiensis*. It is known for its insecticidal properties.

2. **Form of Toxin in Bacteria**: In the bacteria, the Bt toxin is produced in the form of crystals. These crystals contain the toxin in an inactive form.

3. **Inactive Form - Protoxin**: The inactive form of the toxin is referred to as a protoxin. This means that while the toxin is present, it does not exhibit any harmful effects on the bacteria itself.

4. **Activation of Toxin**: The Bt toxin becomes active only when it is ingested by an insect. In the insect's gut, the conditions (such as pH and enzymes) facilitate the conversion of the protoxin into its active form.

5. **Reason for Non-Harm to Bacteria**: Since the Bt toxin remains in its inactive form (protoxin) within the bacteria, it does not kill the bacteria that produce it. The bacteria can produce the toxin without harming themselves.

6. **Conclusion**: Therefore, the crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because the toxin is inactive (as protoxin) within the bacteria and only becomes active upon entering the body of an insect.

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