Question

Crystalline protein synthesized by Bacillus thuringiensis is activated by

• A. Alkaline pH of bacteria
• B. Alkaline pH in the insect foregut
• C. Alkaline pH in the insect midgut
• D. Acidic pH in the insect gut

Answer 1

The correct option is C Alkaline pH in the insect midgut

The crystalline (Cry) protein synthesized by Bacillus thuringiensis exists as a set of inactive protoxins, but once a target insect ingests the Cry protein, this protein gets solubilized in its alkaline midgut and activated by the protease present in it. This is followed by binding to specific receptors located in the insect midgut epithelial cells which creates pores that eventually lead to the death of the insect.