Activation of Spores of Bacillus cereus by  -Radiation

Abstract

S U M M A R YSpores of Bacillus cereus strain PX which were exposed to 0.02, 0.06, 0.18, 0.54 and 1-08 Mrad of y-radiation became progressively more activated, i.e. they germinated more rapidly in the presence of germinants (e.g. L-alanine, inosine, rt-dodecylamine, calcium dipicolinate) than did unirradiated spores. Heat-and radiation-activation differed in that irradiated spores but not heated spores germinated faster than untreated control spores in n-dodecylamine. The two methods of activation were similar in that both sorts of activated spores could be de-activated, and heated and irradiated spores both had increased contents of titratable thiol groups as compared with untreated spores. Germination-like changes still occurred rapidly in spores which had been subjected to doses of y-radiation sufficient to render them non-viable. Ionizing radiation, heat and other agents which activate spores probably do so by changing the tertiary structure of spore macromolecules and thereby exposing previously masked reactive sites which are important in germination.

Inactivation of Bacterial Spores by Hydrostatic Pressure

“…Further evidence is provided by the pressure inactivation being greatest near neutral pH values. The effects of heat (Curran & Evans, 1945) and y-radiation (Gould & Ordal, 1968) as 'activating' treatments for germination could explain their potentiation of the lethality of pressure for spores. Germination (at I atm.)…”

Mechanism of the Inhibition of Germination of Bacterial Spores by -radiation in the Presence of Iodoacetamide and Iodate

“…Irradiated spores of Bacillus cereus PX germinated more rapidly than unirradiated spores (Gould & Ordal, 1967) but, in contrast, spores irradiated with IAM or with potassium iodate were inhibited from subsequent germination. Fig.…”

Inhibitory Effect of Spice Powders on the Development of Heated and Irradiated <i>Bacillus subtilis</i> Spores as Evaluated by Calorimetry

“…Gamma-ray injures mainly DNA and the damaged DNA is thought to be repaired during the outgrowth and the early stage of the subsequent vegetative growth in spores. In such gamma-ray damaged spores, the germination system is considered to be unaffected and still functional Gould et al, 1968;Hayashi et al, 1995 . Because it was thought that the target of the gamma-ray irradiation in spores was different from that of spice compounds, the inhibitory effect of spice powder might not be enhanced in suppressing the development of irradiated spores.…”