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The germinability of spores of a psychrotolerant, non‐proteolytic strain of Clostridium botulinum is influenced by their formation and storage temperature
Author(s) -
Evans R.I.,
Russell N.J.,
Gould G.W.,
McClure P.J.
Publication year - 1997
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.1997.00225.x
Subject(s) - clostridium botulinum , spore , strain (injury) , microbiology and biotechnology , biology , food science , anatomy , toxin
The formation and storage temperatures of Clostridium botulinum spores are shown to influence their subsequent ability to germinate. Spores were formed at 10°, 20°, 30° and 37°C and following harvest were stored as aqueous suspensions at 20°C (ambient temperature), 4°C (refrigerated) or −20°C (frozen) for periods of up to 1 month. The spores formed at 20°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° or 30°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°C were germinated at 10°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.