3. Results and discussion
3.1. Germination efficiency of C. difficile spores
Prior to analyzing the survival ability of C. difficile spores at low
temperature, a striking difference in the germination ability of
C. difficile strain R20291 and M120 spores was observed. Estimations
of the % of spores forming colonies (CFU/spore count 100)
showed that only 0.03% of R20291 spores formed viable colonies
while the corresponding value for M120 was ~35% suggesting that
most C. difficile spores were unable to germinate or form colonies.
To confirm that the spore suspensions of both strains were viable,
C. difficile spores were decoated and plated onto BHI agar plates
containing lysozyme, which triggers germination by directly
degrading the spore peptidoglycan cortex (Paredes-Sabja and
Sarker, 2011; Paredes-Sabja et al., 2009). Spore colony-forming efficiency
reached ~90% for both strains indicating that nearly all
spores were fully viable (data not shown).