Table 1.

DPA, core water content, and colony formation of various sporesa

StrainSpore properties
DPA content (μg/OD600)Core wet density (g/ml)Germination
Colonies formed/OD600in 24 hbPhase dark spores in 36 h (%)c
PS533 (wild type)14.81.3656.5 × 107 NDd
FB7215.51.3704 × 104 <0.5
FB108<0.71.2971.3 × 107 40
FB108 (sporulated with DPA)9.71.3454.5 × 105 ND
  • a Spores were prepared, and the DPA content, core wet densities, and colonies formed/OD600 on LB medium plates were determined as described in Materials and Methods.

  • b Values are averages of data from two determinations on one spore preparation. These values differed by <2-fold between three different spore preparations. After germination with CaDPA prior to spreading onto LB medium plates, the values for all four strains were 108 colonies formed/OD600 in 24 h.

  • c Spores (107/ml) were incubated at 37°C in 10 mM Tris-HCl (pH 7.4) for 36 h, and then 120 to 200 spores were examined in the phase-contrast microscope.

  • d ND, not determined.