Comparative Experiments To Examine the Effects of Heating on Vegetative Cells and Spores ofClostridium perfringensIsolates Carrying Plasmid Genes versus Chromosomal Enterotoxin Genes

Publisher Website
Google Scholar
Abstract
Clostridium perfringensenterotoxin (CPE) is an important virulence factor for bothC. perfringenstype A food poisoning and several non-food-borne human gastrointestinal diseases. Recent studies have indicated thatC. perfringensisolates associated with food poisoning carry a chromosomalcpegene, while non-food-borne human gastrointestinal disease isolates carry a plasmidcpegene. However, no explanation has been provided for the strong associations between certaincpegenotypes and particular CPE-associated diseases. SinceC. perfringensfood poisoning usually involves cooked meat products, we hypothesized that chromosomalcpeisolates are so strongly associated with food poisoning because (i) they are more heat resistant than plasmidcpeisolates, (ii) heating induces loss of thecpeplasmid, or (iii) heating induces migration of the plasmidcpegene to the chromosome. When we tested these hypotheses, vegetative cells of chromosomalcpeisolates were found to exhibit, on average approximately twofold-higher decimal reduction values (Dvalues) at 55°C than vegetative cells of plasmidcpeisolates exhibited. Furthermore, the spores of chromosomalcpeisolates had, on average, approximately 60-fold-higherDvalues at 100°C than the spores of plasmidcpeisolates had. Southern hybridization and CPE Western blot analyses demonstrated that all survivors of heating retained theircpegene in its original plasmid or chromosomal location and could still express CPE. These results suggest that chromosomalcpeisolates are strongly associated with food poisoning, at least in part, because their cells and spores possess a high degree of heat resistance, which should enhance their survival in incompletely cooked or inadequately warmed foods.