Question

What triggers activation of protoxin to active Bt toxin of Bacillus thuringiensis in bollworm?

• A. Body temperature
• B. The moist surface of midgut
• C. Alkaline pH of the gut
• D. Acidic pH of the stomach

Answer 1

The correct option is C

Alkaline pH of the gut

The correct option is C.

Explanation of the correct option:

1. Bacillus thuringiensis produces a toxic insecticidal protein crystal during their growth.
2. Initially, they are inactive but when ingested by insects they convert to the active toxin.
3. This conversion is mainly due to the alkaline condition of the gut which makes it solubilize.
4. This activated toxin binds epithelial cells and forms pores which leads to lysis and finally death of the insect.

Explanation of the incorrect options:

Option A:

To convert protoxin to active toxin an optimum body temperature of the insect is not required.

Option B:

To convert protoxin to active toxin the moist surface of the midgut is not required.

Option D:

To convert protoxin to active toxin acidic pH of the stomach is not required.

Final answer: Alkaline pH of the gut triggers activation of protoxin to active Bt toxin of Bacillus thuringiensis in bollworm.