Evaluation of media, time and temperature of incubation, and method of enumeration of several strains fo Clostridium perfringens spores.

Two basal media, containing the ingredients found in common in both SPS (BBL) and TSN (BBL) media and in the previously described media of Schaedler et al. (1965) and Starr et al (1971), but minus antibiotics, were selected as the most suitable for the enumeration of Clostridium perfringens spores in a model system. These media were also used to study the influence of the presence of glucose, xylose, or ribose in various concentrations (0, 0.01, 0.1, and 1.0%) on colony morphology and spore recovery. As the sugar concentration in the basal agar medium increased, the colonies of all the test organisms also increased in size, and more of the black colonies became white in color. At the 1.0% sugar level, glucose permitted only white colony development, whereas the pentoses were completely inhibitory. Both pour plates and most-probable-number tubes were inoculated with the spores of several strains of C. perfringens and incubated at 20, 30, 37, and 45 C for 24, 48, and 72 h. Statistical analyses of the enumeration data indicated, at the 99% confidence level, that a Trypticase(BBL)-yeast extract-glucose-sulfite-iron agar gave maximal population estimates at 37 C in 72 h.