Important Interactions with Membrane Receptors in the Mode of Action of Bacillus thuringiensis Cry Toxins

4 Bacillus thuringiensis (Bt) is an aerobic, spore-forming bacterium that produces, during the sporulation phase, crystalline inclusions composed of proteins known as δ-endotoxins (3). The δ-endotoxins form two multigenic families, Cry and Cyt toxins. Cry proteins are specifically toxic to several orders of insects: Lepidoptera, Coleoptera, Hymenoptera, Diptera, and to nematodes. In contrast, Cyt toxins are mostly found in Bt strains active against Diptera (3).