What is the mechanism of action of Bt toxin Class 12?

When Bt toxin is ingested by an insect, it is converted into its active form due to the alkaline pH of the gut. The activated toxin binds to the surface of the epithelial cells of the midgut and create pores. Water entered causes swelling and lysis of cells in insect body.

How does Bacillus thuringiensis Bt work?

Bacillus thuringiensis (Bt) is a species of bacteria that lives in soil. It makes proteins that are toxic to some insects when eaten, but not others. The proteins are not toxic to humans because, like all mammals, we cannot activate them. Bt is not toxic to non-target wildlife.

How does the Bt toxin function as an insecticide?

Susceptible insects must ingest Bt toxin crystals in order to be affected. In contrast to poisonous insecticides that target the nervous system, Bt acts by producing a protein that blocks the digestive system of the insect, effectively starving it.

How does Cry toxin kills the insect?

Three-domain Cry toxins from Bacillus thuringiensis kill insect cells by inserting pores into the membrane. Pore insertion is assisted by transient interactions with ABC transporters. Cry toxins have diversified to target different ABC families in the course of evolution.

What is Bt and how is it produced?

Bt Crops are transgenic crops that produce the same toxin as the bacterium Bacillus thuringiensis in the plant cell, thereby, protecting the crops from pests. The bacterium secretes specific proteins known as “cry proteins” that are toxic to insects. A few of the Bt crops include cotton, brinjal, corn, etc.

What is Bt cotton explain in detail?

What is Bt Cotton? Bt cotton has been genetically modified by the insertion of one or more genes from a common soil bacterium, Bacillus thuringiensis. These genes encode for the production of insecticidal proteins, and thus, genetically transformed plants produce one or more toxins as they grow.

How does Bacillus thuringiensis kills its host larva?

In order to work as a biological insecticide, B.t. or its spores or crystal toxins must be must be eaten by the insect. Inside the insect, the crystal toxins bind to cells of the gut wall, and cause these cells to break apart. Within minutes of eating B.t, the insect stops feeding.

How is Bacillus thuringiensis used as an insecticide?

Bacillus thuringiensis (Bt) bacteria synthesize different insecticidal proteins named Cry, Vip, and Cyt that are able to kill different insect orders, or nematodes. These proteins have been extensively used in insect control practices in agriculture as sprays or expressed in genetically modified plants.

Why does Bacillus thuringiensis produce toxins?

Once ingested by insects, these crystals are solubilized in the midgut, the toxins are then proteolytically activated by midgut proteases and bind to specific receptors located in the insect cell membrane [5,7], leading to cell disruption and insect death.

Where is Bt toxin gene obtained?

c Bacteria Assertion : ‘Bt’ toxin gene has been cloned from bacteria and expressed in plants to provide resistance from insect without the need of insecticides. Reason: ‘Bt’ toxin is produced from bacterium Bacillus thuringiensis.

Which toxin is produced by Bacillus thuringiensis?

Abstract. Bacillus thuringiensis bacteria produce different insecticidal proteins known as Cry and Cyt toxins. Among them the Cyt toxins represent a special and interesting group of proteins. Cyt toxins are able to affect insect midgut cells but also are able to increase the insecticidal damage of certain Cry toxins.