THURINGENESIS TOXIN AS A NATURAL PESTICIDE.pptx

THURINGENESIS TOXIN AS A NATURAL PESTICIDE

1. Topic:- THURINGENESIS TOXIN AS A NATURAL PESTICIDE Submitted by:- BSc. Biotechnology 3 rd year

2. Introduction Bacillus thuringiensis ( Bt ) is a Gram-positive, rod-shaped, motile, and aerobic or facultative anaerobic bacterium that produces insecticidal crystal inclusions, known as δ-endotoxins or Cry proteins, during its sporulation phase of growth. These Cry proteins have been proven to be effective against important crop pests. They’re called “genetically engineered” or “transgenic” crops because they use DNA from Bt bacteria. The plants make Bt proteins (toxins) that only target specific insects. The Bt toxin made by the plant is called a “plant-incorporated protectAnt .

3. Bt is a bacterium that is found naturally in soils throughout the world. To
reproduce, . Bt spores have proteins that are toxic to insect larvae when eaten. There are many types of Bt. Each type or strain affects different insect
groups. Target insects include the beetle family, the fly family including mosquitoes, and the butterfly family. It is used to kill beetles and the larvae of mosquitoes, black flies, and moths. Bt is also toxic to nematodes. Common types of Bt strains: Bt israelensis controls immature mosquitos, flies, and gnats. Bt aizawai and Bt kurstaki controls caterpillars of moths and butterflies. Bt tenebrionis and Bt japonensis control beetle larvae. Bt san diego controls beetle larvae.

4. Mode of action :- • The Cry protein is made as an inactive protoxin .
Cry protein has to be eaten to cause mortality.
Conversion of the protoxin (e.g., 130 kDa ) into the active toxin (e.g., 68 kDa ) called delta endotoxin requires the combination of a slightly alkaline pH (7.5-8) and the action of a specific protease(s) found in the insect gut
The active toxin binds to protein receptors on the insect gut epithelial cell membrane.
. The toxin forms pores in the insect gut.which leads to epithelial cell lysis . This cytolysis leads to gut paralysis, cessation of feeding and finally death from starvation

5. Development of some B.thurengenesis transgenic crops For insect resistant

6. Advantages – It helps in improving the crop yield, thereby, raising the farmer’s income. This results in increased farm production.
They help in controlling soil pollution as the use of synthetic pesticides is reduced. Bt crops help in protecting beneficial insects.
It can easily feed an increasing population due to increased yields in a short time.
It leads to the production of disease-free crops owing to the reduction of pesticides.
It leads to more productivity in a small area of land.

7. Disadvantage – Bt crops are costlier than naturally grown crops.
It can disrupt the natural process of gene flow.
The pests might become resistant to the toxins produced by these crops and the crop production might decline.