• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.489-493
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• 1988

To obtain a new yeast strain that is able to efficiently produce ethanol from starch, the glucoamylase gene of Saccharomyces diastaticus was transformed into S. cerevisiae without a cloning vector. The competent cells of S. cerevisiae, induced by the treatment of Li$_2$SO$_4$, were transformed with the partial BamHI-digests of chromosomal DNA of S. diastaticus, and the transformants were selected by their abilities to utilize and ferment starch. The transformants, which appeared at a frequency of 8.5$\times$10$^{-7}$, were able to withstand up to 800 ppm of copper sulfate like the recipient and retained the phenotypic expression of the recipient with the exception of the acquisition of STA gene and MAL gene, as regards fermentation of carbohydrates. The enzymatic properties of glucoamylases produced by transformants were very similar to those produced by S. diastaticus as based on optimium pH and temperature.

• 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 Microbiology
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• v.49 no.2
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• pp.200-204
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• 2013

To contruct amylolytic industrial strains of Saccharomyces cerevisiae which produce ethanol efficiently from raw starch, the Bacillus amyloliquefaciens ${\alpha}$-amylase genes (Amy) or Aspergillus awamori glucoamylase genes (GA1) was separately introduced into the ribosomal DNA loci in the chromosomes of the raw starch fermenting-parental strain (ATCC 9763/$YIp{\delta}AGSA{\delta}$), using double 18S rDNA-integration system. Ethanol production after 3 days of fermentation by the strain that produced ethanol most efficiently from raw starch (ATCC 9763/$YIp{\delta}AGSA{\delta}$/YIpAG2rD) among the transformant strains was 1.5-times higher than that by the parental strain. This new strain generated 9.2% (v/v) ethanol (72 g/L) from 20% (w/v) raw corn starch and consumed 75% of the raw starch content during the same period.