Biology ETDs

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Spores of Bacillus subtilis var. niger and Clostridium sporogenes were exposed to heat and radiation, separately, and in simultaneous combination. The spores were subjected to treatment under two sets of conditions. Wet spores were suspended in water during treatment, while spores in the dry state were treated in air which had a relative humidity of about 30% at room temperature. Treatment with ionizing radiation at room temperature was found to be more effective in the dry than the wet state, in contrast to most theories and some research in that area. Bacillus subtilis var. niger was more resistant to heat than Clostridium sporogenes when dry spores were compared. When wet spores were heated the situation was reversed. Thermoradiation response in both wet and dry states showed an increase in D10 values (the dose required for a one log reducation in population) as dose rate increased. Three dimensional plots of the synergistic response of wet spores to thermoradiation treatment showed the most effective combinations of heat and radiation to be in the temperature range of 50 to 60 ° C with dose rates of about 10 krads/hour. During thermoradiation treatment, all application of heat and ionizing radiation was simultaneous. In the dry state the synergism increased as the temperature or dose rate, or both, were increased. This was true at all temperatures above 80° C.



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Degree Name


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Department Name

UNM Biology Department

First Committee Member (Chair)

Larry L. Barton

Second Committee Member

John August Ulrich

Third Committee Member

Paul Richard Kerkof

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Biology Commons