Submitted to: Canadian Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2003
Publication Date: 4/1/2003
Citation: Novak, J.S., Juneja, V.K., Mcclane, B.A. 2003. An ultrastructural comparison of spores from various strains of clostridiumperfringens and correlations with heat resistance parameters. Canadian Journal of Microbiology. 86:239-247 Interpretive Summary: Clostridium perfringens is a frequent food-borne pathogen in temperature- abused foods. Previous studies had shown that food-borne human disease isolates differed from non food-borne disease isolates in the location of the C. perfringens enterotoxin (cpe) gene, plasmid or chromosome, in relation to their heat resistance properties. The spore structure is largely responsible for resistance of C. perfringens to cooking temperatures of 100 C for 60 min. This study used spore ultrastructural measurements to correlate spore structure sizes with heat resistance and survival potential of the spores from different strains of C. perfringens. A negative correlation was found between spore core size and heat resistance supporting the importance of core dehydration in stabilizing spore heat resistance. Therefore, the control of spore hydration may result in decreased requirements for heat or cooking treatments to inactivate spore-forming pathogens and produce a safer food supply.
Technical Abstract: It has been shown that Clostridium perfringens isolates associated with food poisoning carry a chromosomal cpe gene, whereas non-food-borne human gastrointestinal disease isolates carry a plasmid cpe gene. In addition the chromosomal cpe gene isolates exhibit higher heat resistance as compared with the plasmid cpe strains. Therefore, the current study conducted ultrastructural measurements of spores from several plasmid and chromosomal cpe-positive C. perfringens isolates. In support of the dehydration mechanism of spore heat resistance, the C. perfringens spore core average size was found to show a negative correlation with D-values for spores obtained at 100 C. Dipicolinic acid (DPA) concentrations assayed for the spores did not correlate well with C. perfringens spore core averages nor with D-values at 100 C. Spore core size might be a distinguishing phenotypic characteristic used to identify heat resistance and survival potential of C. perfringens in improperly cooked foods.