Evidence for contribution of neutral trehalase in barotolerance of Saccharomyces cerevisiae

in yeast, trehalose accumulation and its hydrolysis, which is catalyzed by neutral trehalase, are believed to be important for thermotolerance, We hav e shown that trehalose is one of the important factors for barotolerance (r esistance to hydrostatic pressure); however, nothing is known about the rol e of neutral trehalase in barotolerance. To estimate the contribution of ne utral trehalase in resisting high hydrostatic pressure, we measured the bar otolerance of neutral trehalase I and/or neutral trehalase II deletion stra ins. Under 180 MPa of pressure for 2 h, the neutral trehalase I deletion st rain showed higher barotolerance in logarithmic-phase cells and lower barot olerance in stationary-phase cells than the wild-type strain, Introduction of the neutral trehalase I gene (NTH1) into the deletion mutant restored ba rotolerance defects in stationary-phase cells, Furthermore, we assessed the contribution of neutral trehalase during pressure and recovery conditions by varying the expression of NTN1 or neutral trehalase activity with a gala ctose-inducible GAL1 promoter with either glucose or galactose, The low bar otolerance observed with glucose repression of neutral trehalase from the G AL1 promoter was restored during recovery with galactose induction. Our res ults suggest that neutral trehalase contributes to barotolerance, especiall y during recovery.