EFFECT OF TEMPERATURE ON THE RATE OF GERMINATION IN BACILLUS CEREUS.

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.