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प्रश्न
On spraying Bacillus thuringiensis on an infected cotton crop field the pests are killed by the toxin, however the toxin although produced by the bacteria does not affect it. Explain giving reason.
उत्तर
Bacillus thuriengiensis is a microorganism that produces the bt toxin. These bacteria produce intracellular crystal structures known as endotoxin during the sporulation process, which contains an insecticidal protein. Because the endotoxin that builds up in the bacteria is an inactive precursor, bt toxin kills the insect that consumes it but not the bacterium that makes it. Only the alkaline stomach of insects can activate it. By attaching to the interior of the insect's midgut, the protoxin damages the surface barrier by causing holes that result in swelling and lysis. This damage is done by the protoxin being cleaved by proteases (alkaline conditions in the gut) when the insect ingests it. As a result, the insect is unable to consume and dies from starvation.
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