Question

The bacterium Bacillus thuringiensis is widely used in contemporary biology as ____.

• A. Source of industrial enzyme
• B. Indicator of water pollution
• C. Insecticide
• D. Agent for production of dairy products

Answer 1

The correct option is C Insecticide

• Bacillus thuringiensis (Bt) is a gram-positive bacterium that produces crystals during sporulation.
• These crystals consist of pro-toxins called crystal proteins which are highly specific insecticides.
• Once ingested by the host insect, these crystals dissolve in the alkaline conditions of the gut, thereby activating the pro-toxins.
• The active toxins then binds to receptors on midgut epithelial cells. This binding will create pores in the midgut's wall, causing cell death through osmotic lysis finally killing the insect.

Thus the correct answer is option C.