The co-action of osmotic and high temperature stresses results in a growth improvement of Debaryomyces hansenii cells.

Debaryomyces hansenii is a salt tolerant yeast species, often isolated from sea water or found among other spoilage yeasts in several types of food. In this work, we examined the influence of temperature and increased osmotic pressure (two parameters also important in food industry) on D. hansenii growth. Several other authors showed that its growth at the normal yeast cultivation temperature (28 to 30 degrees C) is stimulated by the presence of sodium, in contrast to the growth of Saccharomyces cerevisiae, which is inhibited by the presence of sodium under the same experimental conditions. Here we show that the previously reported growth stimulation by sodium is temperature dependent in D. hansenii and can be observed under conditions that already amount to high temperature stress for D. hansenii. At a lower temperature (more convenient for D. hansenii cultivation), we found no significant improvement or even an inhibition of cell growth in the presence of Na(+). The growth of D. hansenii at high temperatures is also improved by the presence of potassium or sorbitol. Moreover, the temperature dependence of stimulatory effects of increased osmotic pressure in media does not seem to be unique for D. hansenii; similar relationships between the growth, cultivation temperature and presence of osmolytes we also observed for S. cerevisiae and Schizosaccharomyces pombe.