FIG. 4.

Electron micrographs of sporulated wild-type and engineered strains of B. thuringiensis, illustrating crystals typical of these strains. (A) Wild-type B. thuringiensis subsp. morrisoni (strain tenebrionis) DSM 2803. (B) Acrystalliferous strain (4Q7) of B. thuringiensis subsp. israelensis transformed with pPFT3A (cry3A without the STAB-SD sequence under the control of cytA promoters). (C and D) Cross section (C) and sagittal section (D) through 4Q7 cells transformed with pPFT3As (cry3A with the STAB-SD sequence under the control of cytA promoters). All micrographs are at the same magnification. Bar, 300 nm.