Cry-like genes, in an uncommon gene configuration, produce a crystal that localizes within the exosporium when expressed in an acrystalliferous strain of Bacillus thuringiensis.

Cry proteins are pesticidal toxins produced by the bacterium Bacillus thuringiensis (Bt), which aggregate in sporulating cells to form a crystal. Except in a relatively few cases, these crystals are located outside the exosporium that surrounds the spore. Bt2-56 is a strain of Bt that has the relatively uncommon characteristic of locating its Cry protein-containing crystal within the exosporium, and in association with a long, multifiber filament.