title: Direct ethanol production from barley beta-glucan by sake yeast displaying Aspergillus oryzae beta-glucosidase and endoglucanase.
abstract: Three beta-glucosidase- and two endoglucanase-encoding genes were cloned from Aspergillus oryzae, and their gene products were displayed on the cell surface of the sake yeast, Saccharomyces cerevisiae GRI-117-UK. GRI-117-UK/pUDB7 displaying beta-glucosidase AO090009000356 showed the highest activity against various substrates and efficiently produced ethanol from cellobiose. On the other hand, GRI-117-UK/pUDCB displaying endoglucanase AO090010000314 efficiently degraded barley beta-glucan to glucose and smaller cellooligosaccharides. GRI-117-UK/pUDB7CB codisplaying both beta-glucosidase AO090009000356 and endoglucanase AO090010000314 was constructed. When direct ethanol fermentation from 20 g/l barley beta-glucan as a model substrate was performed with the codisplaying strain, the ethanol concentration reached 7.94 g/l after 24 h of fermentation. The conversion ratio of ethanol from beta-glucan was 69.6% of the theoretical ethanol concentration produced from 20 g/l barley beta-glucan. These results showed that sake yeast displaying A. oryzae cellulolytic enzymes can be used to produce ethanol from cellulosic materials. Our constructs have higher ethanol production potential than the laboratory constructs previously reported.
authors.affiliation: Research Institute, Gekkeikan Sake Co Ltd, Kyoto 612-8385, Japan. a_kotaka@gekkeikan.co.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kotaka
authors.forename: Hiroki
authors.initials: H
authors.lastname: Bando
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kaya
authors.forename: Michiko
authors.initials: M
authors.lastname: Kato-Murai
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kuroda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sahara
authors.forename: Yoji
authors.initials: Y
authors.lastname: Hata
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Ueda
mesh_terms: D002480:Cellulase / Q000235:genetics / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D001467:Hordeum / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D014920:Wine / Q000382:microbiology*; D047071:beta-Glucans / Q000378:metabolism*; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D047071:beta-Glucans; D000431:Ethanol; D001617:beta-Glucosidase; D002480:Cellulase