title: Construction of a xylose-metabolizing yeast by genome integration of xylose isomerase gene and investigation of the effect of xylitol on fermentation.
abstract: A yeast with the xylose isomerase (XI) pathway was constructed by the multicopy integration of XI overexpression cassettes into the genome of the Saccharomyces cerevisiae MT8-1 strain. The resulting yeast strain successfully produced ethanol from both xylose as the sole carbon source and a mixed sugar, consisting of xylose and glucose, without any adaptation procedure. Ethanol yields in the fermentation from xylose and mixed sugar were 61.9% and 62.2% of the theoretical carbon recovery, respectively. Knockout of GRE3, a gene encoding nonspecific aldose reductase, of the host yeast strain improved the fermentation profile. Not only specific ethanol production rates but also xylose consumption rates was improved more than twice that of xylose-metabolizing yeast with the XI pathway using GRE3 active yeast as the host strain. In addition, it was demonstrated that xylitol in the medium exhibits a concentration-dependent inhibition effect on the ethanol production from xylose with the yeast harboring the XI-based xylose metabolic pathway. From our findings, the combination of XI-pathway integration and GRE3 knockout could be result in a consolidated xylose assimilation pathway and increased ethanol productivity.
authors.affiliation: Department of Chemical and Environmental Engineering, Gunma University, Kiryu, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Tanino
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hotta
authors.forename: Tomonori
authors.initials: T
authors.lastname: Ito
authors.forename: Jun
authors.initials: J
authors.lastname: Ishii
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Yamada
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Hasunuma
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ogino
authors.forename: Naoto
authors.initials: N
authors.lastname: Ohmura
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ohshima
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D000449:Aldehyde Reductase / Q000235:genetics; D019747:Aldose-Ketose Isomerases / Q000235:genetics* / Q000378:metabolism*; D004734:Energy Metabolism / Q000235:genetics; D000431:Ethanol / Q000302:isolation & purification / Q000378:metabolism; D005285:Fermentation / Q000187:drug effects; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005784:Gene Amplification; D015870:Gene Expression; D005818:Genetic Engineering; D005947:Glucose / Q000378:metabolism; D008031:Lignin / Q000378:metabolism; D020085:Neocallimastigales / Q000235:genetics*; D010427:Pentose Phosphate Pathway / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D014170:Transformation, Genetic; D014993:Xylitol / Q000494:pharmacology; D014994:Xylose / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin; D014994:Xylose; D000449:Aldehyde Reductase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; D005947:Glucose; D014993:Xylitol