title: Co-fermentation of cellulose/xylan using engineered industrial yeast strain OC-2 displaying both β-glucosidase and β-xylosidase.
abstract: We constructed a recombinant industrial Saccharomyces cerevisiae yeast strain OC2-AXYL2-ABGL2-Xyl2 by inserting two copies of the β-glucosidase (BGL) and β-xylosidase (XYL) genes, and a gene cassette for xylose assimilation in the genome of yeast strain OC-2HUT. Both BGL and XYL were expressed on the yeast cell surface with high enzyme activities. Using OC2-AXYL2-ABGL2-Xyl2, we performed ethanol fermentation from a mixture of powdered cellulose (KC-flock) and Birchwood xylan, with the additional supplementation of a 30-g/l Trichoderma reesei cellulase complex mixture. The ethanol yield (gram per gram of added cellulases) of the strain OC2-AXYL2-ABGL2-Xyl2 increased approximately 2.5-fold compared to that of strain OC2-Xyl2, which lacked β-glucosidase and β-xylosidase activities. Notably, the concentration of additional T. reesei cellulase was reduced from 30 to 24 g/l without affecting ethanol production. The BGL- and XYL-displaying industrial yeast of the strain OC2-AXYL2-ABGL2-Xyl2 represents a promising yeast for reducing cellulase consumption of ethanol fermentation from lignocellulosic biomass by compensating for the inherent weak BGL and XYL activities of T. reesei cellulase complexes.
authors.affiliation: Toyota Biotechnology & Afforestation Laboratory, Toyota Motor Co, 1099 Marune, Kurozasa-cho, Miyoshi, Aichi, 470-0201, Japan. Satoshi_Saito@mta.mx.toyota.co.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Saitoh
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tanaka
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D002480:Cellulase / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering; D007218:Industrial Microbiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics; D014990:Xylans / Q000378:metabolism*; D014995:Xylosidases / Q000235:genetics / Q000378:metabolism*; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D014990:Xylans; D002482:Cellulose; D014995:Xylosidases; D001617:beta-Glucosidase; D002480:Cellulase