FIG. 5.

Viability of C. difficile sleC mutant spores. Numbers of heat-resistant CFU were determined for (A) C. difficile 630Δerm and CRG1115 (sleC) spores and (B) C. difficile R20291 and CRG1166 (C. difficile R20291 sleC) spores. Spore cultures were heated at 60°C for 25 min before they were plated onto BHIS agar (filled bars) or BHIS agar supplemented with 0.1% taurocholate (bars with diagonal lines). Spores were also decoated as described in Materials and Methods before they were plated onto BHIS agar supplemented with 1 μg/ml lysozyme (bars with horizontal lines). The bars indicate the averages of three independent experiments, and the error bars indicate standard errors of the means. The detection limit for the assay was 50 CFU/ml.