Question

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

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

Answer 1

The correct option is C Alkaline pH of gut

Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (bollworms) and dipterans. B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein which exists as inactive protoxins but when an insect (bollworm) ingests the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals.