FIG. 2.

Dependency of lonB-lacZ expression, illustrated by time courses of lonB-lacZ-driven β-galactosidase production in a wild-type strain (AH2356; inverted triangles) and in strains bearing deletion mutations of the following loci: sigF (AH2358; squares), sigE (AH2359; circles), sigG (AH2360; diamonds), and sigK (AH2361; triangles). Sporulation was induced by the resuspension method. Samples were collected every 30 min after the resuspension and onset of sporulation (T₀) and assayed for β-galactosidase activity. Enzyme activity is indicated in Miller units (see Materials and Methods). Background levels of enzyme activity in the wild-type strain MB24 were subtracted in all cases.