Question

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

• A. Bt toxin protein is not produced in the bacillus
• B. Bt toxin protein is produced in very less amount in the bacillus
• C. Bt toxin exists as inactive toxin
• D. Bt toxin can’t cause any damage to bacillus.

Answer 1

The correct option is C Bt toxin exists as inactive toxin

The Bt toxin protein exists as an inactive protoxin in the Bacillus but once an insect ingests the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilises the crystals. The activated protein then kills the insect by inducing bleeding and auto-digestion.