[Effect of 2,4-dinitrophenol on stability of a turbidostat yeast culture to heat shock].

The resistance of a turbidostat culture of Saccharomyces cerevisiae 14 to heat shock was investigated. The growth rate of the turbidostat culture after a cultivation temperature shift from a suboptimal (20 degrees C) or optimal (30 degrees C) value to a supraoptimal value of 37.5 degrees C was taken as an index of heat-shock resistance. Experiments were performed in both the two variants: with 2,4-dinitrophenol (DNP) present in cells and medium and with DNP present only in the medium. Cells were found to be resistant to heat shock when they contained no DNP; intracellular DNP did not prevent the formation of the system responsible for thermotolerance, but hindered the functioning of this system. The resistance of yeast to heat shock is presumably determined by the efficiency of oxidative phosphorylation.