Inclusion bodies and crystals of Bacillus sphaericus mosquitocidal proteins expressed in various bacterial hosts

Mosquitocidal proteins of 42 and 51 kDa from Bacillus sphaericus were produced in acrystallogenic B. sphaericus and B. subtilis strains. In both species, transformants containing each protein expressed individually were non-toxic for mosquito larvae and produced small inclusions which did not have a crystalline ultrastructure. When both components of the binary toxin were expressed together, toxicity was restored: oval and round amorphous inclusions were produced in B. subtilis, and typical native-type crystals were synthesized in B. sphaericus. In B. subtilis, native-type crystals were produced only when the two components of the binary toxin were synthesized as a 93-kDa fusion protein.