title: Heterologously expressed Aspergillus aculeatus β-glucosidase in Saccharomyces cerevisiae is a cost-effective alternative to commercial supplementation of β-glucosidase in industrial ethanol production using Trichoderma reesei cellulases.
abstract: Trichoderma reesei is a filamentous organism that secretes enzymes capable of degrading cellulose to cellobiose. The culture supernatant of T. reesei, however, lacks sufficient activity to convert cellobiose to glucose using β-glucosidase (BGL1). In this study, we identified a BGL (Cel3B) from T. reesei (TrCel3B) and compared it with the active β-glucosidases from Aspergillus aculeatus (AaBGL1). AaBGL1 showed higher stability and conversion of sugars to ethanol compared to TrCel3B, and therefore we chose to express this recombinant protein for use in fermentation processes. We expressed the recombinant protein in the yeast Saccharomyces cerevisiae, combined it with the superb T. reesei cellulase machinery and used the combination in a simultaneous saccharification and fermentation (SSF) process, with the hope that the recombinant would supplement the BGL activity. As the sugars were processed, the yeast immediately converted them to ethanol, thereby eliminating the problem posed by end product inhibition. Recombinant AaBGL1 activity was compared with Novozyme 188, a commercially available supplement for BGL activity. Our results show that the recombinant protein is as effective as the commercial supplement and can process sugars with equal efficiency. Expression of AaBGL1 in S. cerevisiae increased ethanol production effectively. Thus, heterologous expression of AaBGL1 in S. cerevisiae is a cost-effective and efficient process for the bioconversion of ethanol from lignocellulosic biomass.
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Treesukon
authors.initials: T
authors.lastname: Treebupachatsakul
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Nakazawa
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Shinbo
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fujikawa
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Asami
authors.initials: A
authors.lastname: Nagaiwa
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ochiai
authors.affiliation: Graduate School of Agriculture and Biological Sciences and Research Institute for Advanced Science and Technology, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka, 599-8531, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawaguchi
authors.affiliation: Department of Chemical Engineering, Ichinoseki College of Technology, Takanashi, Hagisho, Ichinoseki, Iwate, 021-8511, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Nikaido
authors.affiliation: Department of Chemical Engineering, Ichinoseki College of Technology, Takanashi, Hagisho, Ichinoseki, Iwate, 021-8511, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Totani
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Shioya
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Shida
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Morikawa
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan. Electronic address: owataru@vos.nagaokaut.ac.jp.
authors.forename: Wataru
authors.initials: W
authors.lastname: Ogasawara
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Okada
mesh_terms: D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics; D018533:Biomass; D002475:Cellobiose / Q000378:metabolism; D002480:Cellulase / Q000378:metabolism*; D000431:Ethanol / Q000191:economics* / Q000378:metabolism*; D005285:Fermentation; D008031:Lignin / Q000378:metabolism; D011994:Recombinant Proteins / Q000191:economics / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D014242:Trichoderma / Q000201:enzymology*; D001617:beta-Glucosidase / Q000191:economics / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; C036909:lignocellulose; D002475:Cellobiose; D000431:Ethanol; D008031:Lignin; C427304:Novozym 188; D001617:beta-Glucosidase; D002480:Cellulase
keywords: Aspergillus aculeatus β-glucosidase; Cel3B; Ethanol; GH3; Saccharomyces cerevisiae; Simultaneous saccharification and fermentation; Trichoderma reesei