SUMMARY
Subculture counts using 16 different media representing three general types (fresh‐meat infusion, formulated media, and dehydrated) were compared for the recovery of severely heated spores of two strains of PA3679. Comparative tests with these same media were made on the recovery of heated spores of PA3679, which had been produced in four sporogenic media. In general, the subculture media prepared from fresh‐meat infusions showed the highest recovery counts for all spore suspensions in all experiments. Dehydrated media showed the poorest recovery. The intermediate counts with the formulated media overlapped the counts with the other two groups of media. Pork‐pea infusion extract and beef infusion extract consistently yielded the highest counts and were appreciably higher than any of the dehydrated media. Differences were noted between the response of the two strains of PA3679 to the various subculture media. In addition, differences were noted between the responses to various subculture media on a single strain when the spores were grown on different substrates. Spores of a single strain of PA3679 grown in different substrates showed marked differences in heat resistance.