FIG. 4.

(A, B) Effects of elevated levels of the GerA GR on commitment and DPA release during B. subtilis spore germination. Commitment (•, ▾, ▪) and DPA release (○, ▿, □) of heat-activated spores of B. subtilis strains PS533 (wild type) (A) and PS3476 (PsspD::gerA) (B) germinating with various concentrations of l-valine were measured as described in Materials and Methods. Circles, triangles, and squares, respectively, denote l-valine concentrations of 10, 4, and 1 mM (A) or 10, 2, and 0.5 mM (B). The maximum number of RFU that each germination assay reached upon germination for 5 h in panel A and for 3 h in panel B was set at 100%, but the actual germination percentages of spore samples at the end of germination incubations were 95, 90, and 45% in panel A and 95, 86, and 74% in panel B, going from the highest to the lowest l-valine concentration. Note that the PS533 spore preparation used in the experiment shown is different from the one used in the experiment shown in Fig. 3. However, differences in rates of commitment and DPA release for l-valine germination between B. subtilis spore preparations did not affect the conclusions made in this work about factors important in determining the timing of commitment and DPA release for spore populations.