ACCUMULATION OF POLYOLS AND SUGARS IN SOME SUGAR-TOLERANT YEASTS

Accumulation of polyols and sugars in 7 strains of sugar-tolerant yeasts grown in the presence of high concentrations of glucose, sucrose, and sodium chloride was compared. Primary intracellular solutes accumulated in 4 species, Debaryomyces hansenii, Hansenula anomala, Zygosaccharomyces rouxii, and Candida tropicalis were glycerol and D-arabitol, and in Aureobasidium sp. erythritol was accumulated instead Of D-arabitol. Saccharomyces cerevisiae and Torulaspora delbrueckii accumulated trehalose as well as glycerol (and D-arabitol). The fact that significant differences were observed in the amounts of the intracellular polyols, depending on the kind of media solute suggested that there were differences between the yeasts' glucose-tolerance and sucrose-tolerance as well as between sugar-tolerance and salt-tolerance. In most strains, larger amounts of polyols accumulated intracellularly in high-solute media as compared to low-solute medium. But their total concentration was at most about 1 m, 30-40% of the extracellular solute concentrations. The intracellular polyols accumulated in high-solute media released extracellularly. These results suggested that intracellular polyols such as glycerol and D-arabitol could contribute to the osmoregulation of sugar-tolerant yeasts, although they might not always be produced for it. Glycerol was shown to be an important intracellular solute for osmoregulation.