FIG. 1.

(A to F) Commitment and DPA release during the germination of B. subtilis and B. cereus spores. Heat-activated spores of B. subtilis strain PS533 (wild type) were germinated in 2 mM l-alanine (A, B), heat-activated spores of B. subtilis strain PS3415 (PsspB::gerB*) were germinated in 150 μM l-asparagine (C, D), and heat-activated spores of B. cereus were germinated in 40 mM NH₄Cl and 6 mM l-alanine (E, F). d-Alanine (A and E) or acetic acid (C) was added to germination incubations at zero time and other times, as indicated by arrows 1, 2, and 3, denoting 2.5, 5, and 10 min (A, C) or 1, 1.5, and 2 min (E), and commitment and DPA release during incubations with or without d-alanine or acetic acid addition were determined as described in Materials and Methods. Shown in panels B, D, and F are normalized commitment (•) and germination (○) curves derived from data in panels A, C, and E, respectively, as described in Materials and Methods. The maximum number of RFU that each germination assay reached upon germination for 2 h in panels A and C and for 30 min in panel E was set at 100%, but the actual germination percentages of spore samples at the end of germination incubations were 95, 90, and 95% in panels A, C, and E, respectively. Note that in the experiments in panels A, C, and E, d-alanine was added at many more times than shown and only data from three d-alanine addition times are shown for clarity. However, data for all d-alanine addition times are shown in panels B, D, and F.