FIG 4.

Characterization of the C. perfringens F4969 nanI null mutant. (A) PCR analysis of the wild-type F4969 strain shows genes for all three C. perfringens sialidases (nanH, nanI, nanJ) and the cpe gene. The mutant strain carries the wild-type nanH, nanJ, and cpe genes but has a 0.9-kb intron insertion in its nanI gene. The leftmost lane contains molecular size markers (the numbers on the left are in base pairs). (B) Southern blot hybridization of an intron-specific probe with DNA from the wild-type F4969 or the nanI null mutant strain. A single intron insertion was detected using DNA only from the nanI null mutant. The leftmost lane contains DNA fragment size markers. (C) Sialidase activity analyses for the wild-type F4969, nanI null mutant, and complemented strains using 16-h TH broth culture supernatants. *, P < 0.05. The error bars indicate standard errors. OD₅₉₅, optical density at 595 nm.