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. 2009 Nov 20;192(3):657–664. doi: 10.1128/JB.01209-09

FIG. 3.

FIG. 3.

Development of heat-resistant CFU of C. difficile mutants over 5 days. Cultures of C. difficile were incubated anaerobically at 37°C in BHIS broth. Every 24 h, samples were heat treated at 60°C for 25 min before they were plated onto BHIS agar supplemented with 0.1% taurocholate and incubated at 37°C for 24 h. The numbers of heat-resistant CFU per milliliter were determined. The symbols 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. (A) •, C. difficile 630Δerm; ▴, CRG1115 (sleC); ○, CRG1555 (CRG1115 complemented with parental sleC gene); □, CRG1556 (CRG1115 harboring pMTL84151 empty vector control); ▪, CRG1651 (C. difficile 630Δerm harboring pMTL84151); ▾, CRG878 (CD3563); ⧫, CRG789 (spo0A). (B) (○), C. difficile R20291; •, CRG1166 (sleC); ▪, CRG1634 (CRG1166 complemented with parental sleC); ▾, CRG1628 (CRG1166 harboring pMTL84151); ⧫, CRG1652 (C. difficile R20291 harboring pMTL84151); ▴, CRG1375 (spo0A). All data points for CRG1115 and CRG789 in panel A and for CRG1166, CRG1628, and CRG1375 in panel B are overlaid because there was no heat-resistant colony formation.