Bacillus thuringiensis (Bt) strains have been used for designing...

Bacillus thuringiensis producte endotoxin (Cry proteins) during the stationary phase of its growth cycle which when ingested and released in the gut of the larvae of insect pest, disrupts the insect gut lining thereby killing earthen. In this way, it act as a bioinsecticide. Related Theory Scientists identify and isolate the gene that produces the lethal protein. The gene is removed from the bacterium and a gene conferring resistance to a chemical (usually antibiotic or herbicide) is attached that will prove useful in a later step. The Bt gene with the resistance gene attached is inserted into plant cells. Any plant cell that has the Bt gene must also have the resistance gene that was attached to it. The plant cells are grown in the presence of the antibiotic or herbicide and select the plant cells that are unaffected by it. These genetically transformed plant cells are then grown into whole plants by a process called tissue culture. The modified plants produce the same lethal Bt protein produced by $B$ bacteria because the plants now have the same gene.