Sensitivities of germinating spores and carvacrol-adapted vegetative cells and spores of Bacillus cereus to nisin and pulsed-electric-field treatment.
Treatment of Bacillus cereus spores with nisin and/or pulsed-electric-field (PEF) treatment did not lead to direct inactivation of the spores or increased heat sensitivity as a result of sublethal damage. In contrast, germinating spores were found to be sensitive to PEF treatment. Nisin treatment was more efficient than PEF treatment for inactivating germinating spores. PEF resistance was lost after 50 min of germination, and not all germinated spores could be inactivated. Nisin, however, was able to inactivate the germinating spores to the same extent as heat treatment. Resistance to nisin was lost immediately when the germination process started. A decrease in the membrane fluidity of vegetative cells caused by incubation in the presence of carvacrol resulted in a dramatic increase in the sensitivity to nisin. On the other hand, inactivation by PEF treatment or by a combination of nisin and PEF treatments did not change after adaptation to carvacrol. Spores grown in the presence of carvacrol were not susceptible to nisin and/or PEF treatment in any way.
Agrotechnological Research Institute (ATO), Bornsesteeg 59, 6708 PD Wageningen, The Netherlands. I.E.Pol@ATO.WAG-UR.NL
I E
IE
Pol
W G
WG
van Arendonk
H C
HC
Mastwijk
J
J
Krommer
E J
EJ
Smid
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R
Moezelaar
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001409:Bacillus cereus / Q000187:drug effects / Q000502:physiology*; D000081007:Cymenes; D004574:Electromagnetic Fields; D006358:Hot Temperature; D039821:Monoterpenes; D009561:Nisin / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects / Q000502:physiology; D013729:Terpenes / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D000081007:Cymenes; D039821:Monoterpenes; D013729:Terpenes; D009561:Nisin; C073316:carvacrol