title: Heat shock affects permeability and resistance of Bacillus stearothermophilus spores.
abstract: Heat shock of dormant spores of Bacillus stearothermophilus ATCC 7953 at 100 or 80 degrees C for short times, the so-called activation or breaking of dormancy, was investigated by separating the resulting spores by buoyant density centrifugation into a band at 1.240 g/ml that was distinct from another band at 1.340 g/ml, the same density as the original spores. The proportion of spores at 1.240 g/ml became larger when the original dormant spores were heated for a longer period of time, but integument-stripped dormant spores were quickly and completely converted to spores with a band at 1.240 g/ml. The spores with bands at both 1.240 and 1.340 g/ml were germinable faster than the original dormant spores and thus were considered to be activated. The spores with a band at 1.240 g/ml, which were considered to be fully activated, were apparently permeabilized, with a resulting complete depletion of dipicolinic acid, partial depletion of minerals, susceptibility to lysozyme action, permeation of the gradient medium, changed structural appearance in electron micrographs of thin-sectioned spores, and partly decreased heat resistance (D100 = 453 min) compared with the original dormant spores (D100 = 760 min). However, the fully activated spores with a band at 1.240 g/ml, although devoid of dipicolinic acid, still were much more resistant than germinated spores or vegetative cells (D100 = 0.1 min). The spores with a band at 1.340 g/ml, which were considered to be partly activated, showed no evidence of permeabilization and were much more heat resistant (D100 = 1,960 min) than the original dormant spores.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Microbiology, Michigan State University, East Lansing 48824.
authors.forename: T C
authors.initials: TC
authors.lastname: Beaman
authors.forename: H S
authors.initials: HS
authors.lastname: Pankratz
authors.forename: P
authors.initials: P
authors.lastname: Gerhardt
mesh_terms: D002499:Centrifugation, Density Gradient; D001411:Geobacillus stearothermophilus / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D006358:Hot Temperature; D008854:Microscopy, Electron; D010539:Permeability; D013171:Spores, Bacterial / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure