Synthesis of trehalose in Saccharomycopsis fibuligera sdu under various stress conditions was investigated. Neither the activation of trehalose-6-phosphate synthase (SfTPS1) nor the change in trehalose content was observed under stress exposure of S. fibuligera sdu cells. The results of reverse transcription polymerase chain reaction, which was performed with the specific primers designed to target the SfTPS1 gene fragment cloned from this strain, also showed that all stress treatments did not increase the expression of SfTPS1 gene. These results demonstrated that synthesis of trehalose in response to stress conditions in S. fibuligera sdu clearly differs from that of Saccharomyces cerevisiae and most other fungi. The phylogenetic analysis of the amino acid sequence deduced from the SfTPS1 gene fragment showed that the SfTPS1 sequence formed a separate family that was far related to S. cerevisiae TPS1. The yeast strain, which can accumulate a large amount of trehalose under normal growth conditions, has many applications and TPS1 gene in such strain may have unique use in transgenic organisms.