title: Improvements in ethanol production from xylose by mating recombinant xylose-fermenting Saccharomyces cerevisiae strains.
abstract: To improve the ability of recombinant Saccharomyces cerevisiae strains to utilize the hemicellulose components of lignocellulosic feedstocks, the efficiency of xylose conversion to ethanol needs to be increased. In the present study, xylose-fermenting, haploid, yeast cells of the opposite mating type were hybridized to produce a diploid strain harboring two sets of xylose-assimilating genes encoding xylose reductase, xylitol dehydrogenase, and xylulokinase. The hybrid strain MN8140XX showed a 1.3- and 1.9-fold improvement in ethanol production compared to its parent strains MT8-1X405 and NBRC1440X, respectively. The rate of xylose consumption and ethanol production was also improved by the hybridization. This study revealed that the resulting improvements in fermentation ability arose due to chromosome doubling as well as the increase in the copy number of xylose assimilation genes. Moreover, compared to the parent strain, the MN8140XX strain exhibited higher ethanol production under elevated temperatures (38 °C) and acidic conditions (pH 3.8). Thus, the simple hybridization technique facilitated an increase in the xylose fermentation activity.
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kato
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Suyama
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Yamada
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Hasunuma
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D000449:Aldehyde Reductase / Q000235:genetics / Q000378:metabolism; D050542:D-Xylulose Reductase / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D014994:Xylose; D000449:Aldehyde Reductase; D050542:D-Xylulose Reductase