Widely used microbe in biotech sector

1. MICROBIAL INSECTICIDES-
Bacillus thuringiensis
SHIVANI THORAT
MSC 2
214

2. MICROBIAL INSECTICIDES
Microbially produced toxic
substance that kills an insect.
Organisms used as
insecticides- Bacteria, Fungus,
Virus and nematodes
Bacillus thuringiensis
Gram positive, facultatively aerobic,sporulating soil bacteria
Can infect specific target insect
Parasporal crystal protein  Protoxin/ δ- endotoxin (Cry protein)
Effective mainly against orders Lepidoptera, Diptera, Coleoptera

4. Bt Toxins
α- exotoxin
β- exotoxin
δ- endotoxin (Cry and Cyt proteins)
Hemolysins
Enterotoxins
Phospholipases
Chitinase

5. MODE OF ACTION
 Ingestion of crystals
 Activation of toxin
 Creation of ion channels
Dehydration
Bacteremia Death
USE OF Bt Toxin
Using Bt spores or isolated crystals
as biopesticide

6. GENETIC ENGINEERING
Using Bt to form GMPs/Bt
crops
Gene transfer technique using
Ti-plasmid vector system from
Agrobacterium tumefaciens
Replacing tDNA sequence
with Cry genes

8. Tobacco- First crop  Belgium
Cotton- First use 2002
Mustard- First transgenic food crop
Brinjal
Corn
Maize
Potato
Soyabean
Tomato

9. ADVANTAGES
 Safe for humans and
animals
 Genes are expressed in all
parts of the plant
 Toxins are environmental-
friendly
 Improved resistance to
pests
 Increased crop productivity
 Stability of production
LIMITATIONS
For Bt sprays:
 Poor coverage
 Low efficiency
 Uv degradable
For Bt crops:
 Costly
 Can disrupt natural process
of gene flow
 Risk of toxin resistance and
decline in crop production

10. REFERENCE
• Molecular Biotechnology  Glick
• Microbial Biotechnology- Alexander Glazer & Hiroshi
Nikaido
• Biotechnology  Satyanarayan
• Egyptian journal of biological pest control- article(52) 2018
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035146/
• Researchgate.net BT: applications in agriculture and
insect resistance management
• International scolarly research notices Mode of action
and specificity of Bacillus thuringienses (published: 20 jan
2014)