Toxic component of Bacillus thuringiensis is

Options

A. Alkaloid
B. Steroid
C. Amino acid
D. Protein

Answer

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

1. **Identify Bacillus thuringiensis (Bt):**
- Bacillus thuringiensis is a soil-dwelling, gram-positive bacterium known for its insecticidal properties.

2. **Understand the Mechanism of Action:**
- This bacterium produces spores that contain cryogenes, which are responsible for the production of cryoproteins.

3. **Function of Cryoproteins:**
- Cryoproteins are toxic to certain insects, particularly their larvae. When these proteins are ingested by the larvae, they become activated in the gut.

4. **Effect on Insects:**
- Once activated, the cryoproteins disrupt the intestinal tract of the insect, leading to its death. They are particularly effective against nematodes, dipterans, and lepidopterans.

5. **Analyze the Options:**
- The question provides four options:
- A) Alkaloid
- B) Steroid
- C) Amino acid
- D) Protein
- Since cryogenes encode for cryoproteins, the toxic component of Bacillus thuringiensis must be a protein.

6. **Select the Correct Answer:**
- Based on the analysis, the correct answer is **D) Protein**. The other options (alkaloid, steroid, amino acid) do not represent the toxic component produced by Bacillus thuringiensis.

**Final Answer:**
The toxic component of Bacillus thuringiensis is **D) Protein**.

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