Spore Cortex Hydrolysis Precedes Dipicolinic Acid Release during Clostridium difficile Spore Germination

Area of Science:

• Microbiology
• Bacterial Physiology
• Molecular Biology

Background:

• Clostridium difficile spores cause infections in antibiotic-treated hosts.
• Spore germination is essential for C. difficile pathogenesis, transitioning from dormant spores to toxin-producing vegetative cells.
• Germination is triggered by bile acids and glycine, with CspC identified as the bile acid receptor.

Purpose of the Study:

• To investigate the sequence of events in Clostridium difficile spore germination.
• To compare the germination pathway of C. difficile with the well-studied model organism Bacillus subtilis.
• To elucidate the roles of the germinant receptor CspC and cortex hydrolase SleC in C. difficile spore germination.

Main Methods:

• Comparative analysis of spore germination stages.
• Genetic inactivation of key germination proteins (cspC and sleC).
• Monitoring of dipicolinic acid (DPA) release and cortex hydrolysis.

Main Results:

• Cortex hydrolysis precedes dipicolinic acid (DPA) release in C. difficile spore germination.
• Inactivation of CspC or SleC blocked both cortex hydrolysis and DPA release.
• C. difficile spore germination follows a novel pathway distinct from B. subtilis.

Conclusions:

• Clostridium difficile spore germination initiates with cortex hydrolysis, followed by DPA release.
• The germinant receptor CspC and cortex hydrolase SleC are essential for this novel germination pathway.
• Understanding this pathway has implications for controlling C. difficile infections.