EFFECT OF RADIATION ENVIRONMENT ON THE THERMAL RESISTANCE OF IRRADIATED SPORES OF BACILLUS SUBTILIS
An attempt was made to determine the effect of environmental conditions during irradiation on the degree of induced heat sensitization B. subtilis on spores. The degree of heat sensitization induced in the spores by gamma irradiation was not changed when irradiation was carried out at low oxygen tension (1 mm Hg) as compared with irradiation in air. Heat sensitization was slightly greater at pH 7.0 than at pH 4.5. Culture media were found to influence the degree of induced heat sensitivity, with less effect being produced by complex organic substrates. Thus, radioinduced thermal sensitization was slightly greater when the spores were suspended in phosphate buffer (pH 7.0) as compared with nutrient broth or ham puree: the same effect was observed with spores of Clostridium sporogenes. Apparently, the complex molecules in the organic substrates compete with the free radicals formed during irradiation of the aqueous solvent and thus protect the spores from indirect effects during irradiation. B. subtilis was sensitized to heat less by irradiation at 90 deg C than was C. sporogenes P.A. 3679. A dose of approximates 800,000 rep prior to heating was required to reduce the D value (decimal reduction time) of C. sporogenes P.A. 3679 by 90%, whereas with B. subtilis 1,200,000 rep was needed to cause a 90% decrease in the D value. A possible explanation for this is that the catalase of B. subtilis might destroy any hydrogen peroxide formed within the spore during irradiation and thus prevent damage from this toxic compound. Sporeg of C. sporogenes P.A. 3679 being catalase-negative might be injured to a greater degree during irradiation than spores of B. subtilis. (BBB)
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge
- NSA Number:
- NSA-17-035468
- OSTI ID:
- 4659184
- Journal Information:
- Applied Microbiology (U.S.) Changed to Appl. Environ. Microbiol.ed as Arch. Pathol. (March 1928-September 1950 and July 1960-December 1975) and as AMA, Journal Name: Applied Microbiology (U.S.) Changed to Appl. Environ. Microbiol.ed as Arch. Pathol. (March 1928-September 1950 and July 1960-December 1975) and as AMA Vol. Vol: 11; ISSN APMBA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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EFFECT OF RADIATION ENVIRONMENT ON THE THERMAL RESISTANCE OF IRRADIATED SPORES OF BACILLUS SUBTILIS
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