Trehalase Activity and Trehalose Content in a Freeze-tolerant Yeast, Torulaspora delbrueckii, and Its Freeze-sensitive Mutant

Abstract

Two types of trehalase activities different in the optimum reaction pH (4.3 and 6.7) were found in a freeze-tolerant yeast, Torulaspora delbrueckii D2-4, and three types of the activities at pH 4.3, 5.7, and 6.7 were found in its freeze-sensitive mutant (60B3). The pH 4.3 activities in the cell extracts of the two strains were on the same level, but the pH 6.7 activity in the strain D2-4 was about half of that in the strain 60B3. The enzyme with the pH 4.3 activity and the other two enzymes were analogous to acid and neutral trehalases, respectively, in the sensitivity to metal ions and in response to phosphorylation and dephosphorylation. The trehalose content in the strain D2-4 was three times higher than that in the strain 60B3. The change of trehalose content during growth of the strain 60B3 correlated only to the change of the pH 5.7 activity.