• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.494-498
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• 1988

The optimum conditions for glucoamylase production, and ethanol productivity of the transformant TSD-14 were investigated as compared with the parental strains. The properties of TSD-14 were comparatively similar to the donor S. diastaticus IFO 1046 as regards the conditions of glucoamylase production and ethanol productivity. The soluble starch was the most effective carbon source for the glucoamylase production. While inorganic nitrogen sources did not prompt cell growth and enzyme production, the organic nitrogen sources generally enhanced both cell growth and glucoamylase production. The metal salts such as FeSO$_4$, MgSO$_4$, MnCl$_2$, and NiSO$_4$were favorable to the enzyme production. And the optium temperature and initial pH for glucoamylase production were 3$0^{\circ}C$ and 5. The transformant TSD-14 produced 8.3%(v/v) ethanol from 15% sucrose medium, 4.8%(v/v) ethanol from 15% soluble starch medium, and 7.5%(v/v) ethanol from 15% liquefied potato starch medium. The corresponding fermentation efficiency were 84% , 45% and 70%, respectively.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.403-409
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• 1992

For the development of a glucanolytic yeast strain. the seceretion of endo-1.4-$\beta$-D-glucanase (CMCase) of Bacillus subtilis was performed in yeast using glucoamylase gene (STA1) of Saccharomyces diastaticus. A 1.7 kb-DNA fragment of STA1 gene containing authentic promoter, signal sequence, threonine serine-rich (TS) region and N-terminal region (98 amino acids) of mature glucoamylase was ligated to YEp 24. E. coli-yeast shuttle vector. And then. CMCase structural gene of B. subtilis was fused in frame with the 1.7 kb-DNA fragment of STA1 gene, resulting in recombinant plasmid pYES('24. Yeast transformant harboring pYESC24 had no CMCase activity. So. we deleted TS region and N-terminal region of mature glucoamylase existing between signal sequence and CMCase structural gene in pYESC24. consequently constructed recombinant plasmid pYESC11. The yeast transformed with the newly constructed recombinant plasmid pYESC11 efficiently secreted CMCase to extracellular medium. After 4 days culture. total CMCase activity of this transformant was 44.7 units/ml and over 93% of total CMCase activity was detected in culture supernatant.

• Korean Journal of Microbiology
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• v.32 no.4
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• pp.271-279
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• 1994

To develop a yeast strain which stably secretes both $\alpha$-amylase and glucoamylase and therefore is able to convert starch directly to ethanol, a mouse salivary $\alpha$-amylase cDNA gene with a yeast alcohol dehydrogenase I promoter has been introduced into the cell of a Saccharomyces diactaticus hybrid strain secreting only glucoamylase. To secrete both enzymes more stably without loss of the $\alpha$-amylase gene during a cell-multiplication, an integrating plasmid vector containing $\alpha$-amylase gene was constructed and introduced into the yeast cell. The results showed that the linearized form of the integrating vector was superior in the transformation efficiency and the rate of the expression of the $\alpha$-amylase gene than the circular type of the vector. The yeast transformant having a linearized plasmid vector exhibited higher mitotic stability than the yeast transformant habouring episomat plasmid vector. The transformant containing the linearized vector producing both $\alpha$-amylase and glucoamylase exhibited 2-3 times more amylolytic activity than the original untransformed strain secreting only glucoamylase.

• Korean Journal of Food Science and Technology
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• v.41 no.5
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• pp.541-546
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• 2009

The objectives of this study were to evaluate the physico-chemical and sensory characteristics of a Korean traditional alcoholic beverage (yakju) prepared using different nuruk (Korean-style koji) concentrations and yeasts such as the fusant FA776 and Saccharomyces cerevisiae KOY-1, respectively. The fusant FA776, which has alcohol-fermenting and starch-utilizing properties, was formed by Saccharomyces cerevisiae KOY-1 and Saccharomyces diastaticus KCTC1804. The fermentation trial was conducted in a 5 L lab-scale jar at $25^{\circ}C$. The maximum alcohol production of the K-100 and F-50 reached levels of 135.0 mg/mL and 119.4 mg/mL, respectively. The pH values were in a range of 4.3-4.5. Total acidity was in a range of 0.47-0.60%. Organic acids and amino acids were analyzed in order to evaluate variations in its composition and content via HPLC analysis. Organic acids including lactic acid, citric acid, malic acid, and pyruvic acid, and 16 kinds of amino acids, including aspartic acid, were detected in all treatments. K-100 showed the highest amino acid contents, whereas F-50 exhibited the lowest amino acid contents. Volatile flavor components such as phenylethyl alcohol, isoamyl alcohol, 2-methylthiophane, isobutyl alcohol, and ethyl succinate were detected as a major component in all treatments, as determined via gas chromatography. The results of our sensory evaluation demonstrated that Yakju fermented by the FA776 fusant yielded more favorable results than S. cerevisiae KOY-1.