Influence of Trehalose Accumulation on Response to Freeze Stress in Baker's Yeast

Accumulation of trehalose is suggested to be a critical determinant in improving the stress tolerance of the yeast Saccharomyces cerevisiae. To test the influence of trehalose accumulation on response to freeze stress, we constructed all single and double gene disruption mutants of the trehalase genes ATH1, NTH1 and NTH2 and examined the changes of their trehalose accumulations and their freeze tolerances. Under the condition of freeze stress, three mutants, Δnth1, Δnth2Δnth1, and Δath1Δnth1, all of which carry the NTH1 gene disruption, showed increased trehalose accumulation as compared to the parent strain and other mutants. Moreover, compared with the parent strain BY-6, the NTH1 disruption mutants possessed higher cell survival ratios and greater relative leavening abilities. The results indicated that NTH1 gene is important for trehalose degradation under conditions of freeze stress, thus closely correlated with freeze tolerance of baker's yeast.