| Trehalose is a non-reducing disaccharide that has been found in many organisms. In addition to being nonreducing, it possesses several unique physical properties, which account for the principal role of trehalose as a stress metabolite. It is now being recognized as a crucial defense mechanism that stabilizes proteins and biological membranes under a variety of stress conditions. Based on its unique properties trehalose has become an important target for biotechnology, where it is produced for food manufacture, vaccine protection, pharmaceuticals and cosmetic products.In the previous studies, we found that Saccharomycopsis fibuligera sdu could accumulate trehalose efficiently (up to 0.18g/g dry weight) at the entrance of stationary phase during growth on starch as the sole carbon source. But the strain can synthesize acid trehalase and neutral trehalase, which can mobilize trehalose accumulated by the cells. To enhance yields of trehalose in this strain, it is important to delete or decrease the activity of the acid and neutral trehalases in the cells. By mutagenesis of EMS (Ethylmethanesulfonate), one mutant (All) that assimilated trehalose slowly, but grew on other carbon sources as fast as its parent strain, was isolated. In shaking 300 mL flask, the content of trehalose in the mutant All was increased by 50% than that of the wild type strain when grown in YPS medium. The activities of acid and neutral trehalases of this mutant were lower than those of the wild type. As a result, trehalose accumulation was distinctly advanced in the mutantAll.Trehalose-6-phosphate synthase (SfTps1) activity was detected in the cell extract of S. fibuligera, suggesting that trehalose synthesis pathway in this strain was as same as that in S. cerevisiae and E. coli. The SfTps1 was purified 33-fold to homogeneity by ultrafiltration and several steps of column chromatography. The purified enzyme has apparent molecular masses of 66 kDa, as determined by Native-PAGE and SDS-...
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