Activated forms of Bacillus thuringiensis insecticidal toxins have consistently been found to
form insoluble and inactive precipitates when they are expressed in Escherichia coli.
Genetic engineering of these proteins to improve their effectiveness as biological pesticides
would be greatly facilitated by the ability to express them in E. coli, since the molecular
biology tools available for Bacillus are limited. To this end, we show that activated B.
thuringiensis toxin (Cry1Ac) can be expressed in E. coli as a translational fusion with the …

Disclosed herein are activated Bt toxins expressed in E. coli as a translational fusion with a
phage coat protein of filamentous phage. Phage displaying this fusion protein were viable,
infectious, and as lethal as pure toxin on a molar basis when fed to insects susceptible to
native Bt toxins.