| Trehalose (α-D- glucopyranosyl-1-1-α-glucopyranose) is widely present in bacteria, yeasts, and fungi as well as some insects, invertebrates and plants. Recent results have shown that trehalose does not only primarily function as a reserve carbohydrate but also as a highly efficient protectant, enhancing the resistance of cellular components against adverse conditions such as high temperature, freezing, low dehydration, high osmotic pressure and high concentration of ethanol. These unique protective properties of trehalose make it an interesting compound for several applications, for example as cryoprotectant for cells in medicine and microbiology, as an effective component in cosmetics, as a stabilizer for clinical reagents and bioproducts, or even as a preservative for fresh foodstuff. Thus, much attention has been directed to inexpensive means for producing trehalose.It is thought that starch is the best substrate for production of trehalose due to its low price and easily obtained raw material. Pretorius et al stated that among 150 yeast species that are capable of using starch as carbon and energy sources, Saccharomycopsis fibuligera which expresses raw starch-degrading glucoamylase in addition to α-amylase with debranching activity degrades starch with great efficacy. In the previous studies, trehalose accumulation from starch by Saccharomycopsis fibuligera. sdu was examined and 18.0 % (w/w) trehalose accumulated in the yeast cells (cell dry weight) was observed within 48 h of fermentation. It was shown that S. fibuligera is a good producer of trehalose from starch. But the yeast strain can synthesize acid trehalase and neutral trehalase which can mobilize trehalose accumulated by the cells. Therefore, it is very important to delete or decrease the activity of acid and neutral trehalases in the yeast in order to enhance trehalose yields.It is not economical to use soluble starch as the substrate for production of trehalose in a large scale. Corn starch is commercially produced in China, much cheaper than soluble starch and easily obtained. A series of studies in shaking flasks were conducted to investigate the feasibility of substituting soluble starch by corn starch to accumulate trehlose by strain All. In this study, we found that All accumulated more trehalose in the media containing com starch than in those containing souble starch.Effect of different aeration rate, agitation speed and concentration of com starch on direct conversion of com starch to trehalose by mutant All of Saccharomycopsis fibuligera were examined by using a Biostat B2 2-1 fermentor in this study. We found that the optimal conditions for direct conversion of com starch to trehalose by the mutant were that agitation speed was 200 rpm, aeration rate was 4 1 min'1, concentration of com starch was 2.0% (g ml"1) , initial pH was 5.5, fermentation temperature was 30 °C. Under these conditions, over 22.9% (g g"1) of trehalose was accumulated in the yeast cells, cell yield was 1.52 g of cell dry weight per 100 ml of the fermentation medium, 0.12 % (gml"1) of reducing sugar and 0.21% (gnu"1) of total sugar were left in the fermented medium within 48 h of fermentation.In this paper, hot distilled water was used to extract trehalose from the cells of All. It was found that trehalose extraction by hot distilled water was more efficiency in volume-production.After purification process, trehalose crystal with high purity was got in this study.
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