Divalent Cation Signaling in Clostridium perfringens Spore Germination.

Spore germination plays an essential role in the pathogenesis of Clostridium perfringens -associated food poisoning. Germination is initiated when bacterial spores sense various stimuli, including chemicals and enzymes. A previous study showed that dipicolinic acid (DPA) chelated with calcium (Ca-DPA) significantly stimulated spore germination in C. perfringens . However, whether Ca 2+ or DPA alone can induce germination is unknown. Therefore, we aimed to evaluate the possible roles of Ca 2+ and other divalent cations present in the spore core, such as Mn 2+ and Mg 2+ , in C. perfringens spore germination. Our study demonstrated that (i) Ca-DPA, but not DPA alone, induced C. perfringens spore germination, suggesting that Ca 2+ might play a signaling role; (ii) all tested calcium salts induced spore germination, indicating that Ca 2+ is critical for germination; (iii) the spore-specific divalent cations Mn 2+ and Mg 2+ , but not Zn 2+ , induced spore germination, suggesting that spore core-specific divalent cations are involved in C. perfringens spore germination; and (iv) endogenous Ca 2+ and Mg 2+ are not required for induction of C. perfringens spore germination, whereas exogenous and partly endogenous Mn 2+ are required. Collectively, our results suggest that exogenous spore core-specific divalent cation signals are more important than endogenous signals for the induction of spore germination.