Radiation resistance of spores of some Clostridium perfringens strains.

Clostridium perfringens spores (eight strains) were irradiated in a model system with 60Co gamma rays at -30 C. The quantal response data obtained were analyzed with extreme value statistics. It was found (at the 95% confidence level) that all eight strains followed the same rate of death and that this rate was probably (at the 95% level) not exponential. The statistics did not exclude, however, a normal, lognormal, Weibull, or related rate of spore kill. A more definitive study would be required to distinguish between the latter distributions.

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.

Clostridium perfringens. I. Sporulation in a biphasic glucose-ion-exchange resin medium.

A biphasic culture medium suitable for cultivation and sporulation of Clostridium perfringens, C. botulinum, and C. sporogenes was devised. The medium designed for use in a disposable, compartmented, plastic film container contained peptones, yeast extract, minerals, an anion exchange resin, and glucose in 4% agar as the solid phase and (NH(4))(2)SO(4) and 0.1% agar as the liquid phase. With the biphasic system, it was not necessary to use active cultures as inocula. Growth was at least equal to that obtained in conventional media, and spore production of 9 out of 12 strains of C. perfringens equalled or usually exceeded that of conventional media.