ELEVATION OF THE HEAT-RESISTANCE OF VEGETATIVE CELLS AND SPORES OF CLOSTRIDIUM-PERFRINGENS TYPE-A BY SUBLETHAL HEAT-SHOCK

The degree of heat resistance conferred on Clostridium perfringens by a heat shock, the kinetics of this development, and its duration were determined. A sublethal heat shock at 55 degrees C for 30 min increase d the heat tolerance of vegetative cells at least two-to threefold, Th e acquired tolerance was maintained for 2 h after the heat shock treat ment. Heat shock applied for the first hour of incubation produced spo res more tolerant to heat than the spores of the control. Acquired the rmotolerance is of importance in the case of this organism because of its inherently high optimal growth temperature.