Question

In case of Bacillus thuringiensis, the bacterium itself is not killed by the toxic crystal protein produced by it because Bt toxin

• A. cannot cause any damage to the bacterium
• B. exists as the inactive toxin
• C. protein is produced in very less amount in the bacterium
• D. protein is not produced in the bacterium

Answer 1

The correct option is B exists as the inactive toxin

The Cry protein (an endotoxin) coded by the cry gene of Bacillus thuringiensis is a protoxin and has insecticidal properties. It kills certain insects such as lepidopterans, dipterans, coleopterans, etc.

The endotoxin gets activated in the alkaline environment of the insect gut and causes perforations in the epithelial lining of the midgut. This is followed by cell swelling and cell lysis.