FIG 2.

Percentages of individual C. difficile spores that had lost DPA or became phase dark after HP treatment at 550 MPa. C. difficile ATCC 43601 spores were exposed to 550 MPa of HP for various times as described in Materials and Methods. Samples treated for various times were assayed for DPA release (○) by measuring either DPA released in germination supernatant fluid (A) or the percentage of individual spores that had lost DPA or spores that had become phase dark (B) (△). All values were corrected for the small percentage (≤2%) of phase-dark spores in the starting spores and the small percentage (<5%) of DPA that was present in the supernatant fluid or absent from untreated spores, all as described in Materials and Methods. In a separate experiment, ∼90% of individual C. difficile spores had lost DPA after 15 min of 550-MPa treatment, while ≤3% of these individual spores had become phase dark (data not shown).