Molecular analysis of ssp3 knock-out mutant. (A) PCR analysis of the total DNAs from C. perfringens wild-type and ssp3 mutant. Total DNA isolated from wild type SM101 and the ssp3 mutant DR101 strains was subjected to PCR analysis using ssp3-specific primer pair CPP13/CPP16. (B) Southern hybridization analysis of total DNAs from C. perfringens wild-type and ssp3 mutant. Two identical Southern blots were prepared using Hpa I-digested DNAs from wild-type (SM101) and ssp3 mutant (DR101) and probed separately with either ssp-specific or catP-specific DIG-labeled probes. The migration of the hybridizing band derived from each strain is indicated between the two blots.