title: Highly efficient bioethanol production by a Saccharomyces cerevisiae strain with multiple stress tolerance to high temperature, acid and ethanol.
abstract: 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 Saccharomyces cerevisiae generated by a spore-to-cell hybridization technique without recombinant DNA technology. A heterothallic strain showing a high-temperature (41°C) tolerant (Htg(+)) phenotype, a derivative from a strain isolated from nature, was crossed with a homothallic strain displaying high-ethanol productivity (Hep(+)), 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(+)) 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(+) Hep(+) Acd(+)) resistant strain TJ14 should be useful for cost-effective bioethanol production under high-temperature and acidic conditions.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita-shi, Osaka 565-0871, Japan.
authors.forename: Suthee
authors.initials: S
authors.lastname: Benjaphokee
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hasegawa
authors.forename: Daiki
authors.initials: D
authors.lastname: Yokota
authors.forename: Thipa
authors.initials: T
authors.lastname: Asvarak
authors.forename: Choowong
authors.initials: C
authors.lastname: Auesukaree
authors.forename: Minetaka
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Chuenchit
authors.initials: C
authors.lastname: Boonchird
authors.forename: Satoshi
authors.initials: S
authors.lastname: Harashima
mesh_terms: D056804:Biofuels; D000431:Ethanol / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development*; D012641:Selection, Genetic; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D056804:Biofuels; D000431:Ethanol; D005947:Glucose