title: Expression of a codon-optimized β-glucosidase from Cellulomonas flavigena PR-22 in Saccharomyces cerevisiae for bioethanol production from cellobiose.
abstract: Bioethanol is one of the main biofuels produced from the fermentation of saccharified agricultural waste; however, this technology needs to be optimized for profitability. Because the commonly used ethanologenic yeast strains are unable to assimilate cellobiose, several efforts have been made to express cellulose hydrolytic enzymes in these yeasts to produce ethanol from lignocellulose. The C. flavigenabglA gene encoding β-glucosidase catalytic subunit was optimized for preferential codon usage in S. cerevisiae. The optimized gene, cloned into the episomal vector pRGP-1, was expressed, which led to the secretion of an active β-glucosidase in transformants of the S. cerevisiae diploid strain 2-24D. The volumetric and specific extracellular enzymatic activities using pNPG as substrate were 155 IU L-1and 222 IU g-1, respectively, as detected in the supernatant of the cultures of the S. cerevisiae RP2-BGL transformant strain growing in cellobiose (20 g L-1) as the sole carbon source for 48 h. Ethanol production was 5 g L-1after 96 h of culture, which represented a yield of 0.41 g g-1of substrate consumed (12 g L-1), equivalent to 76% of the theoretical yield. The S. cerevisiae RP2-BGL strain expressed the β-glucosidase extracellularly and produced ethanol from cellobiose, which makes this microorganism suitable for application in ethanol production processes with saccharified lignocellulose.
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Cinvestav-IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Ríos-Fránquez
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Cinvestav-IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico.
authors.forename: Enrique
authors.initials: E
authors.lastname: González-Bautista
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Cinvestav-IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico. tponce@cinvestav.mx.
authors.forename: Teresa
authors.initials: T
authors.lastname: Ponce-Noyola
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Cinvestav-IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico.
authors.forename: Ana Carmela
authors.initials: AC
authors.lastname: Ramos-Valdivia
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Cinvestav-IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico.
authors.forename: Héctor Mario
authors.initials: HM
authors.lastname: Poggi-Varaldo
authors.affiliation: Departamento de Genética y Biología Molecular, Cinvestav-IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico.
authors.forename: Jaime
authors.initials: J
authors.lastname: García-Mena
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250, Cuernavaca, Morelos, Mexico.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Martinez
mesh_terms: D056804:Biofuels; D002475:Cellobiose / Q000378:metabolism*; D040143:Cellulomonas / Q000201:enzymology*; D002482:Cellulose / Q000378:metabolism; D003062:Codon; D000431:Ethanol / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D001617:beta-Glucosidase / Q000235:genetics* / Q000378:metabolism
chemical_list: D056804:Biofuels; D003062:Codon; C036909:lignocellulose; D002475:Cellobiose; D000431:Ethanol; D002482:Cellulose; D008031:Lignin; D001617:beta-Glucosidase
keywords: Bioethanol; Cellobiose; Cellulomonas flavigena; Saccharomyces cerevisiae; β-Glucosidase expression