Intracellular Level of Trehalose in Soy Sauce Yeasts under Different Stresses

Trehalose can protect organisms against disadvantage conditions, such as high osmolarity, heat, oxidation, desiccation and freezing. In this work, the ability to produce trehalose of soy sauce yeasts was studied first and the results showed that trehalose could be accumulated gradually in logarithmic phase and achieve a concentration peak in stationary phase. Then the relevance of growth conditions and intracellular trehalose level of soy sauce yeasts was investigated. Mutant strains (S3-2, T3-5) which can grow in hypertonic conditions, showed different results from their original organisms Zygosaccharomyces rouxii (S) and Torulopsis versatilis (T). For S and T could increase trehalose level from 7.0% and 7.5% to 8.4% and 9.6% with 9% salt stimulation, respectively. While the mutants could accumulate more trehalose under a higher salt (about 12%) stimulation compared to 0% NaCl situation, which suggested a significant feature of the mutants.And the original strains could increase the trehalose level from 8.4% and 9.6% to 10.1% and 10.9% respectively under heat shock (40 °C, 30mins). Moreover, the mutant strains could also product more trehalose in the thermal stimulation condition, but less than the original ones.