INDUCIBLE THERMOTOLERANCE IN LACTOBACILLUS-BULGARICUS

The effect of a sublethal heat challenge on the subsequent thermotoler ance of Lactobarillus bulgaricus at different stages of growth was inv estigated along with the effect of heating menstrum on survival. The r esponse of the cells to heat stress was shown to be dependent upon bot h cell age and heating menstrum. Heat-inducible thermotolerance could be provoked in cells which had been growing exponentially when they we re subjected to the sublethal heat stress: pre-incubation at 10 degree s C above the optimum growth temperature. The same effect could not, h owever, be reproduced in cells taken from the stationary phase. Cells from the stationary phase were shown to always be more thermotolerant as compared to exponential phase cells. Cells showed a greater thermot olerance when heated in milk as compared to buffer.