Sunday, May 3, 2009
2-47
Construction of yeast strains producing high concentration of ethanol from tapioca by using various genetic methods
Keun Kim, Bioscience and Biotechnology, The University of Suwon, San 2-2, Wau-ri, Bongdam-eup, Hwaseong-si, South Korea
For the development of yeast strains producing fuel ethanol efficiently, various genetic methods such as screening and selection, γ-irradiation-mutation, mutation by chemical mutagen, mating, protoplast fusion and recombinant DNA techniques were used. Totally 330 strains of ethanol-producing yeast strains were collected and their fermentation capabilities were examined. Strain KK1 was selected as the best ethanol producer by screening and selection of yeasts from soils of distillery. The pH-regulated continuous culture selection method was more efficient for the selection of good hybrid strains than the conventional selection method. From the rare-mating between haploid Saccharomyces sp. and polyploid S. cerevisiae and by using continuous culture selection method, hybrid clone KK2 was obtained. This strain was γ-irradiated and finally KK2-7 was selected as the best strain. By repeated γ-irradiation, the best strain KK2-7-2 was selected. From mutagenesis by treatment of NTG, strain NT30-9 was obtained. After protoplast fusion, strain F160 was selected as the best strain. Using rare-mating and recombinant DNA techniques, yeast strain capable of directly fermenting starch has been constructed. All the above genetic methods used were efficient in the developing yeast strains with improved ethanol production.