TABLE 1.

Colony formation by spores of C. perfringens strains^a

Strain (genotype)	Spore titer (CFU/ml/OD600)b
	BHI	BHI + Ca-DPAc	BHI + Lyzd
SM101 (wild type)	3.1 × 107	3.3 × 107	3.9 × 107
DPS101 (gerKA gerKC)	2.6 × 106	3.5 × 106	2.0 × 106
DPS108 (gerKB)	4.4 × 106	4.2 × 106	8.6 × 106

^aHeat-activated spores of various strains were plated on BHI agar, and colonies were counted after anaerobic incubation at 37°C for 24 h.

^bTiters are the average number of CFU/ml/OD₆₀₀ determined in three experiments, and the variance was less than 15%.

^cHeat-activated spores were preincubated with Ca-DPA as described in the text and plated on BHI plates.

^dSpores were decoated, heat activated, and plated on BHI agar containing lysozyme (Lyz), and colonies were counted after anaerobic incubation at 37°C for 24 h.