P-056. Roles of DacB and Spm Proteins in Clostridium perfringens Spore Resistance to Moist Heat, Chemicals and UV Radiation

D. Paredes-Sabja1, N. Sarker1, B. Setlow2, P. Setlow2, M. R. Sarker1;
1Oregon State Univ., Corvallis, OR, 2Univ. of Connecticut Hlth. Ctr., Farmington, CT.

Clostridium perfringens food poisoning is caused mainly by enterotoxigenic type A isolates that typically possess high spore heat-resistance. Previous studies have shown that α/β-type small, acid-soluble proteins (SASP) play a major role in the resistance of C. perfringens spores to moist heat, UV radiation and some chemicals. We now find that the degree of dehydration of the spore core and the spore’s peptidoglycan cortex structure are determined during C. perfringens sporulation by the spm and dacB gene products, respectively. Spores of spm and dacB strains had similar, albeit higher core water content than wild-type spores. The resistance of wild-type, spm and dacB spores to moist heat, hydrogen peroxide, hydrochloride acid, formaldehyde, nitrous acid and UV radiation, as well as the core water content and moist heat resistance of spores prepared at various temperatures has been determined. The results of these analyses suggest that (i) core water content and cortex structure has little if any role in C. perfringens spore resistance to UV and formaldehyde, presumably because these spore’s DNA is saturated with α/β-type SASP; (ii) C. perfringens spore resistance to moist heat and nitrous acid is determined to a large extent by core water content and cortex structure, as increased core water content and a altered cortex structure resulted in spores with lower resistance to these agents; (iii) spore core water content and moist heat resistance is also a function of sporulation temperature, with higher sporulation temperatures giving more moist heat resistant spores that have a decreased core water content; and (iv) factors in addition to Spm and DacB play roles in determining spore core water content and thus spore resistance to moist heat.