Interactive effects of sodium chloride and heat shock on trehalose accumulation and glycerol production by Saccharomyces cerevisiae

Trehalose and glycerol may act as protectors inducing a high tolerance to a range of stresses which appear in the production and industrial utilization of yeast Accumulation of trehalose and glycerol production in Saccharomyces cerevisiae cultures as a response to environmental changes in temperature (30-44 degrees C) and osmotic pressure (0-1 M) was studied, using a Doehlert experimental distribution. Maximum amounts of both compounds were obtained at NaCl concentration of 0.75 M and heat shock temperature of 44 degrees C. A reduction of NaCl concentration to 0.25 nn while maintaining the temperature at 44 degrees C resulted in 73 and 51% reductions for trehalose and glycerol concentrations. The lowest amounts of both solutes were produced in the absence of NaCl at 37 degrees C heat shock. The amounts of both substances nearly doubled when a heat shock to 37 degrees C was performed on 0.5 M of NaCl grown cultures. The increase of NaCl to I nn produced 29.5% more trehalose and 5.5% more glycerol. in trehalose accumulation both NaCl concentration and heat shock temperature contribute in an interactive manner, leading to a more effective synthesis of trehalose than each one per se. NaCl was found to be more important than temperature in glycerol production but the combination of the two factors still encloses a considerable synergistic effect. NaCl contributes with an effect fivefold that of temperature on both responses. General quantification of NaCl inhibition was determined by evaluating the growth inhibition constant (K-i) which was of 2.40 M-1 indicating a reasonable resistance to osmotic stress. (C) 1999 Academic Press.