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What is true about Bt toxin?
A
The concerned $Bacillus$ has antitoxins
B
The inactive protoxin gets converted into active form in the insect gut
C
Bt protein exists as active toxin in the $Bacillus$
D
The activated toxin enters the ovaries of the pest to sterilise it and thus prevent its multiplication
Detailed Solution
The Bt toxin protein exists in the bacterium as an inactive protoxin (crystals), which is why it does not kill the $Bacillus$ itself; the bacterium has no antitoxin.
Once an insect ingests the inactive toxin, the crystals are solubilised by the alkaline pH of its gut and the protoxin is converted into the active form.
The activated toxin binds to the surface of the midgut epithelial cells and creates pores, which cause cell swelling and lysis and eventually the death of the insect.
It does not act on the ovaries or sterilise the pest.
Hence the true statement is that the inactive protoxin gets converted into the active form in the insect gut.
Once an insect ingests the inactive toxin, the crystals are solubilised by the alkaline pH of its gut and the protoxin is converted into the active form.
The activated toxin binds to the surface of the midgut epithelial cells and creates pores, which cause cell swelling and lysis and eventually the death of the insect.
It does not act on the ovaries or sterilise the pest.
Hence the true statement is that the inactive protoxin gets converted into the active form in the insect gut.