In the case of Bacillus thuringiensis , Bacillus itself is not killed by toxic protein crystals produced by it because

Options

A. Bt toxin protein is not produced in the bacteria
B. Bt toxin protein is produced in very less amount in the bacillus
C. Bt toxin exists as an inactive toxin
D. the bacteria is resistant to the Bt toxin

Answer

To solve the question regarding why Bacillus thuringiensis (Bt) is not killed by the toxic protein crystals it produces, we can break down the information provided in the video transcript step by step:

### Step-by-Step Solution:

1. **Understanding Bacillus thuringiensis**:
- Bacillus thuringiensis is a bacterium known for producing toxic proteins that are harmful to certain insects. These proteins are often referred to as Bt toxins.

2. **Production of Bt Toxin**:
- The bacterium produces these toxins in the form of crystals. However, it is important to note that these toxins are produced in an inactive form within the bacterium.

3. **Inactive Form of Toxin**:
- The key reason why Bacillus thuringiensis is not harmed by the toxins it produces is that these proteins exist as inactive forms inside the bacterium. This means that they do not exert their toxic effects on the bacterium itself.

4. **Activation in Insects**:
- When insects consume the plant material that contains the Bt toxin, the alkaline pH in the insect gut activates the inactive form of the toxin. This activation leads to the formation of a toxic active form that can damage the insect's cells.

5. **Conclusion**:
- Therefore, the correct answer to the question is that Bacillus thuringiensis is not killed by the toxic protein crystals because these proteins exist in an inactive form within the bacteria.

### Final Answer:
Bacillus thuringiensis is not killed by the toxic protein crystals it produces because these proteins exist as an inactive form within the bacterium.