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 Darabitol. Saccharomyces cerevisiae and Torulaspora delbrueckii accumulated trehalose

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... s 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 sugartolerant yeasts, although they might not always be produced for it. Glycerol was shown to be an important intracellular solute for osmoregulation. Microorganisms having the ability to thrive in environments with low water activity (aW) include halophilic and halotolerant bacteria, halophilic algae, sugar-* Address reprint requests to: Ms . Keiko Tokuoka,