Evans R I, Russell N J, Gould G W, McClure P J
Biochemistry Unit, School of Molecular and Medical Biosciences, University of Wales, Cardiff, UK.
J Appl Microbiol. 1997 Sep;83(3):273-80. doi: 10.1046/j.1365-2672.1997.00225.x.
The formation and storage temperatures of Clostridium botulinum spores are shown to influence their subsequent ability to germinate. Spores were formed at 10 degrees, 20 degrees, 30 degrees and 37 degrees C and following harvest were stored as aqueous suspensions at 20 degrees C (ambient temperature), 4 degrees C (refrigerated) or -20 degrees C (frozen) for periods of up to 1 month. The spores formed at 20 degrees C germinated most rapidly and to the greatest extent. When the spores were germinated immediately after harvest (fresh), there was no difference in the germinability of those spores formed at 20 degrees or 30 degrees C, whether or not they had been heat-shocked before use. However, following storage overnight or longer, differences in the relative germinabilities of the different spore samples were seen. Spores which had been stored at ambient temperature overnight germinated significantly faster and to a greater extent than did those which had been stored for up to 1 month. Similar differences were also observed between spores germinated fresh and those stored overnight, when the spores were stored refrigerated or frozen. Germinability was also influenced by the temperature of storage, since there were differences between spores formed at the same temperature but stored at different temperatures for the same period of time: for example, when spores which had been formed at 20 degrees C were germinated at 10 degrees C following a heat-shock, those which had been stored at ambient temperature germinated faster and to a greater extent than did those which had been stored refrigerated or frozen. It is concluded that there is a complex interaction between formation, storage and germination temperatures, which determines spore germinability. The fact that the changes are time-dependent and can occur in the frozen state is taken to mean that they are physico-chemical rather than metabolic. It is also significant in relation to refrigerated foods which are at risk from Cl. botulinum in that changes which occur during cool or frozen storage can enhance the germinability of spores if the temperature rises above that of chill cabinets.
肉毒梭菌孢子的形成温度和储存温度被证明会影响其随后的萌发能力。孢子在10℃、20℃、30℃和37℃下形成，收获后作为水悬浮液分别在20℃（室温）、4℃（冷藏）或-20℃（冷冻）下储存长达1个月。在20℃下形成的孢子萌发最快且程度最大。当孢子收获后立即萌发（新鲜状态）时，在20℃或30℃下形成的孢子，无论使用前是否经过热激处理，其可萌发能力没有差异。然而，过夜或更长时间储存后，不同孢子样品的相对可萌发能力出现了差异。在室温下过夜储存的孢子比储存长达1个月的孢子萌发得明显更快且程度更大。当孢子冷藏或冷冻储存时，新鲜萌发的孢子和过夜储存后萌发的孢子之间也观察到了类似的差异。可萌发能力还受储存温度的影响，因为在相同温度下形成但在不同温度下储存相同时间的孢子之间存在差异：例如，当在20℃下形成的孢子在热激后于10℃下萌发时，在室温下储存的孢子比冷藏或冷冻储存的孢子萌发得更快且程度更大。结论是，形成温度、储存温度和萌发温度之间存在复杂的相互作用，这决定了孢子的可萌发能力。这些变化是时间依赖性的且能在冷冻状态下发生，这一事实意味着它们是物理化学变化而非代谢变化。这对于有肉毒梭菌风险的冷藏食品也很重要，因为在冷藏或冷冻储存期间发生的变化，如果温度升至高于冷藏柜温度，可能会增强孢子的可萌发能力。
