Effect of reciprocal pressurization on germination and killing of bacterial spores

We measured the germinating and inactivating effects of reciprocal pressuri zation (consisting of six cycles of 5 min compression and rapid decompressi on) (RP) on bacterial spores compared with the effects of continuous pressu rization (CP) by using heat sensitivity (70 degreesC, 30 min) as a criterio n for germination. There was no significant difference in the germination o f spores by RP and CP, but there was a significant difference in spore inac tivation by RP and CP except for 200 MPa-25 and 35 degreesC. The number of germinated spores was more than the number of inactivated spores following RP and CP. These results indicated that compression could initiate germinat ion, whereas rapid decompression could not initiate germination, but could inactivate the germinated spores. Thus, RP was more effective than CP in in activating spores.