STUDIES ON THE POSTIRRADIATION OXYGEN EFFECT IN BACTERIAL SPORES
Experiments were designed to elucidate the mechanisms of postirradiation effects of oxygen in bacterial spores. Kaolin powder contaminated with spores of Bacillus subtilis was dried, sealed under vacuum, and treated at 22 un. Concent 85% with up to 800 krad of gamma radiation from a Co/sup 60/ source. The criterion of lethal damage was the inability of the spore to give rise to a colony on incubation in nutrient agar. From colony counts of samples yielding surviving fractions less than 0.5, exponential dose/survival curves were constructed and the slopes estimated using the expression: surviving fraction = e/ sup -kD/ where k is the slope and D the dose in krad. The slope is used as a measure of the lethal efficiency of the radiation, higher values of k indicating greater efficiency. The highest level of lethal efficiency shown is that resulting from postirradiation storage of spores in oxygen for 48 hr (k = 0.045 krad/sup -1/). The lowest efficiency is that for identical oxygen treatment preceded by exposure to nitric oxide for 15 min (k = 0.010 krad/sup -1/), showing the prevention of the postirradiation oxygen effect by nitric oxide. Also, the development of the postirradiation oxygen effect can be arrested by removing the oxygen and can be restarted by re-admitting oxygen to the dried spore system. Treatment with nitric oxide between exposures to oxygen, however, prevents further development of the oxygen effect. (TCO)
- Research Organization:
- Univ. of Manchester, Eng.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-019857
- OSTI ID:
- 4699889
- Journal Information:
- Journal of Pharmacy and Pharmacology (England), Vol. Vol: 14; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Gamma Irradiation of Bacillus subtilis Spores
Direct enzymatic repair of deoxyribonucleic acid single-strand breaks in dormant spores