FIG. 1.

Effect of the BclA protein on the germination rates of B. anthracis spores in vitro. (A) Microtiter spectrofluorometric assay of germination of spores in the presence of a germination medium with alanine, adenosine, and Casamino Acids (AAC), as described previously (30). The germination of spores of the wild-type Ames strain (○) and bclA strain (Δ) was monitored every minute for 1 h. The data (percent increase in relative fluorescence units [RFU]) are the relative increase in RFU at a given time point compared to the RFU at time zero, multiplied by 100. Representative data are presented, and similar results were obtained in at least two additional experiments. (B) Germination was also measured by absorbance readings as previously described (19). The A₆₀₀ of each sample was measured at various times and is plotted as the percentage of the initial A₆₀₀ [A₆₀₀ (init)] at time zero that is represented by the A₆₀₀ at a given time point [A₆₀₀ (t)]. Absorbance data are from three independent experiments, and standard errors of the means are depicted.