What triggers activation of protoxin to active toxin of Bacillus thuringiensis in boll worm

Options

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

Answer

D

Explanation

Bacillus thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. These protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to alkaline pH of the gut which solubilize the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis and eventually cause death of insect.