It is well known that trehalose is a stress-induced substance. Many research[16, 18] also pointed that
thermal could stimulate yeast to produce more trehalose. In Saccharomyces cerevisiae, the TPS1 gene was
expressed at very low levels under normal conditions, and increased dramatically with heat shock, but there
was no expression of TPS2 in the control[19]. And the relevance between stimulation such as high osmolarity,
heat and the level of trehalose has also been studied in previous research. But there was little study about salttolerant
yeasts. The aim of this study is to study the capability of producing trehalose of soy sauce yeasts (S, T,S3-2 and T3-5) and how to increase their level of trehalose.