THE INFLUENCE OF THE SPORULATION TEMPERATURE ON THE HEAT RESISTANCE AND CHEMICAL COMPOSITION OF BACTERIAL SPORES

The thermal resistance of spores of Bacillus subtilis and Bacillus coagulans was varied by the production of spore suspensions at selected incubation temperatures. The spores were analyzed for heat resistance and their DPA and cation (Ca++, Mg++, and Mn++) contents. The thermal resistance of the B. subtilis spore suspensions, as well as their DPA and cation content, increased as the sporulation temperature was increased. Spores of B. coagulans showed a similar increase in heat resistance as the sporulation temperature was increased, while the cation content remained essentially constant. The DPA content of the B. coagulans spore suspensions, however, decreased as the sporulation temperature was increased. The ratio of millimoles of cations to the millimoles of DPA per 1 × 1010spores was calculated for the spore suspensions of each organism. For both organisms, this ratio increased as the thermal resistance of the spore suspension increased.