FIG. 4.

β-Galactosidase synthesis in B. thuringiensis 80-21 containing plasmids with the cry1A gene promoter region fused to lacZ. The fusions contained the wild-type promoter (■), the 272 mutant BtII promoter (□), and the 271 mutant BtI promoter (○). The cells were grown and sporulated in G-Tris medium plus 7 μg of chloramphenicol per ml and sampled as described in Materials and Methods. In all cases, exponential growth ended at about 10 h.