An improved sporulation medium has been developed in which all five strains of Clostridium perfringens tested exhibited a 100- to 10,000-fold increase in numbers of spores when compared with spore yields in SEC medium under comparable conditions. In addition, three of five strains produced a 100- to 1,000-fold increase, with the remaining two strains yielding approximately the same numbers of spores, when compared with strains cultured in Ellner medium. At the 40-hr sampling time, 18 of 27 strains produced a 10- to 100-fold increase in numbers of spores in our medium, when compared to spore production obtained in a medium recently reported by Kim et al. The new medium contained yeast extract, 0.4%; proteose peptone, 1.5%; soluble starch, 0.4%; sodium thioglycolate, 0.1%; and Na2HPO4. 7H2O, 1.0%. In some cases, the spore yield could be increased by the addition of activated carbon to the new medium. The inclusion of activated carbon in the medium resulted in spores with slightly greater heat resistance than spores produced in the new medium without added carbon or in SEC or in Ellner medium. The major differences in heat resistance of the various strains appeared to be genetically determined rather than reflections of a particular sporulation medium. A definite heat-shock requirement was shown for four of four strains, with the optimal temperature ranging from 60 C for a heat-sensitive strain to 80 C for a heat-resistant strain. Heating for 20 min at the optimal temperature resulted in a 100-fold increase over the viable count obtained after heating for 20 min at 50 C.
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机译：已经开发了一种改进的孢子形成培养基，其中与可比较条件下的SEC培养基中的孢子产率相比，所测试的所有五个产气荚膜梭菌菌株的孢子数量均显示出100至10,000倍的增加。此外，与在Ellner培养基中培养的菌株相比，五个菌株中的三个菌株增加了100到1,000倍，而其余两个菌株产生的孢子数量大致相同。在40小时的采样时间中，与Kim等人最近报道的在培养基中获得的孢子产量相比，在我们的培养基中27个菌株中有18个菌株的孢子数量增加了10到100倍。新培养基中含有酵母提取物0.4％。蛋白ept，1.5％;可溶性淀粉0.4％巯基乙酸钠，0.1 ％;和Na2HPO4。 7 H 2 O，1.0％。在某些情况下，可以通过向新培养基中添加活性炭来提高孢子产量。培养基中包含活性炭，所产生的孢子的耐热性要比不添加碳的新培养基，SEC或Ellner培养基中产生的孢子的耐热性略高。各种菌株的耐热性的主要差异似乎是由遗传决定的，而不是特定孢子形成介质的反射。对于四个应变中的四个应变，显示出一定的热冲击要求，最佳温度范围从热敏感应变的60℃到耐热应变的80℃。在最佳温度下加热20分钟，比在50℃下加热20分钟后获得的存活数增加100倍。
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