초록
<P>Use of super strains exhibiting tolerance to high temperature, acidity and ethanol is a promising way to make ethanol production economically feasible. We describe here the breeding and performance of such a multiple-tolerant strain of <I>Saccharomyces cerevisiae</I> generated by a spore-to-cell hybridization technique without recombinant DNA technology. A heterothallic strain showing a high-temperature (41°C) tolerant (Htg<SUP>+</SUP>) phenotype, a derivative from a strain isolated from nature, was crossed with a homothallic strain displaying high-ethanol productivity (Hep<SUP>+</SUP>), a stock culture at the Thailand Institute of Scientific and Technological Research. The resultant hybrid TJ14 displayed ability to rapidly utilize glucose, and produced ethanol (46.6g/l) from 10% glucose fermentation medium at high temperature (41°C). Not only ethanol productivity at 41°C but also acid tolerance (Acd<SUP>+</SUP>) was improved in TJ14 as compared with its parental strains, enabling TJ14 to grow in liquid medium even at pH 3. TJ14 maintained high ethanol productivity (46.0g/l) from 10% glucose when fermentation was done under multiple-stress conditions (41°C and pH 3.5). Furthermore, when TJ14 was subjected to a repeated-batch fermentation scheme, the growth and ethanol production of TJ14 were maintained at excellent levels over ten cycles of fermentation. Thus, the multiple-stress (Htg<SUP>+</SUP> Hep<SUP>+</SUP> Acd<SUP>+</SUP>) resistant strain TJ14 should be useful for cost-effective bioethanol production under high-temperature and acidic conditions.</P>