title: Breeding of a xylose-fermenting hybrid strain by mating genetically engineered haploid strains derived from industrial Saccharomyces cerevisiae.
abstract: The industrial Saccharomyces cerevisiae IR-2 is a promising host strain to genetically engineer xylose-utilizing yeasts for ethanol fermentation from lignocellulosic hydrolysates. Two IR-2-based haploid strains were selected based upon the rate of xylulose fermentation, and hybrids were obtained by mating recombinant haploid strains harboring heterogeneous xylose dehydrogenase (XDH) (wild-type NAD(+)-dependent XDH or engineered NADP(+)-dependent XDH, ARSdR), xylose reductase (XR) and xylulose kinase (XK) genes. ARSdR in the hybrids selected for growth rates on yeast extract-peptone-dextrose (YPD) agar and YP-xylose agar plates typically had a higher activity than NAD(+)-dependent XDH. Furthermore, the xylose-fermenting performance of the hybrid strain SE12 with the same level of heterogeneous XDH activity was similar to that of a recombinant strain of IR-2 harboring a single set of genes, XR/ARSdR/XK. These results suggest not only that the recombinant haploid strains retain the appropriate genetic background of IR-2 for ethanol production from xylose but also that ARSdR is preferable for xylose fermentation.
authors.affiliation: Biomass Refinery Research Center (BRRC), National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-0046, Japan, inoue-h@aist.go.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Inoue
authors.forename: Seitaro
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Akinori
authors.initials: A
authors.lastname: Matsushika
authors.forename: Seiya
authors.initials: S
authors.lastname: Watanabe
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sawayama
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics; D002678:Chimera; D003433:Crosses, Genetic; D050542:D-Xylulose Reductase / Q000235:genetics; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering; D005947:Glucose / Q000378:metabolism; D006238:Haploidy; D007218:Industrial Microbiology; D009249:NADP / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*
chemical_list: D000431:Ethanol; D009249:NADP; D014994:Xylose; D000429:Alcohol Oxidoreductases; C035795:D-xylose dehydrogenase; D050542:D-Xylulose Reductase; D017853:Phosphotransferases (Alcohol Group Acceptor); C032700:xylulokinase; D005947:Glucose