EFFECT OF TEMPERATURE ON THE RATE OF GERMINATION IN BACILLUS CEREUS

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Knaysi, Georges (Cornell University, Ithaca, N.Y.). Effect of temperature on the rate of germination in Bacillus cereus. J. Bacteriol. 87:619–622. 1964.—By use of the change of the spores from bright to dark, when observed in dark contrast with a phase microscope, as a criterion for the incipience (first stage) of germination, and increase in the volume of the spore as a criterion for the second stage, it was found that the two stages differed in their cardinal temperatures. In the strain investigated, the first stage has a maximum of about 59, an optimum of 30, and a minimum estimated to be in the neighborhood of −1 C. The corresponding temperatures for the second stage are 44, 35, and 10 C. Spores exposed to temperatures above the maximum for the first stage have a tendency to turn dark at temperatures suitable for germination, and this tendency is not immediately arrested when the spores are exposed to pH 3.2 to 3.4 at 6 C. The potential value of the differences between the cardinal temperatures of the two stages for the control of sporeformers is discussed.

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