title: Enhanced hydrolysis of lignocellulosic biomass: Bi-functional enzyme complexes expressed in Pichia pastoris improve bioethanol production from Miscanthus sinensis.
abstract: Lignocellulosic biomass is the most abundant utilizable natural resource. In the process of bioethanol production from lignocellulosic biomass, an efficient hydrolysis of cellulose and hemicellulose to release hexose and pentose is essential. We have developed a strain of Pichia pastoris that can produce ethanol via pentose and hexose using an assembly of enzyme complexes. The use of enzyme complexes is one of the strategies for effective lignocellulosic biomass hydrolysis. Xylanase XynB from Clostridium cellulovorans and a chimeric endoglucanase cCelE from Clostridium thermocellum were selected as enzyme subunits, and were bound to a recombinant scaffolding protein mini-CbpA from C. cellulovorans to assemble the enzyme complexes. These complexes efficiently degraded xylan and carboxymethylcellulose (CMC), producing approximately 1.18 and 1.07 g/L ethanol from each substrate, respectively, which is 2.3-fold and 2.7-fold higher than that of the free-enzyme expressing strain. Miscanthus sinensis was investigated as the lignocellulosic biomass for producing bioethanol, and 1.08 g/L ethanol was produced using our recombinant P. pastoris strain, which is approximately 1.9-fold higher than that of the wild-type strain. In future research, construction of enzyme complexes containing various hydrolysis enzymes could be used to develop biocatalysts that can completely degrade lignocellulosic biomass into valuable products such as biofuels.
authors.affiliation: Department of Biotechnology, Korea University, Seoul, Republic of Korea.
authors.forename: Sang Kyu
authors.initials: SK
authors.lastname: Shin
authors.affiliation: Department of Biotechnology, Korea University, Seoul, Republic of Korea.|Institute of Life Science and Natural Resources, Korea University, Seoul, Republic of Korea.
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Hyeon
authors.affiliation: Department of Biotechnology, Korea University, Seoul, Republic of Korea.
authors.forename: Young In
authors.initials: YI
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, Korea University, Seoul, Republic of Korea.
authors.forename: Dea Hee
authors.initials: DH
authors.lastname: Kang
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, Seoul, Republic of Korea.
authors.forename: Seung Wook
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, Kwangwoon University, Seoul, Republic of Korea.
authors.forename: Chulhwan
authors.initials: C
authors.lastname: Park
authors.affiliation: Department of Biotechnology, Korea University, Seoul, Republic of Korea. samhan@korea.ac.kr.
authors.forename: Sung Ok
authors.initials: SO
authors.lastname: Han
mesh_terms: D056804:Biofuels; D018533:Biomass; D002480:Cellulase / Q000235:genetics / Q000378:metabolism; D018556:Crops, Agricultural / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism*; D010843:Pichia / Q000201:enzymology* / Q000235:genetics; D006109:Poaceae / Q000378:metabolism*; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D056804:Biofuels; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin; D001617:beta-Glucosidase; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases; C090001:XynB xylanase
keywords: Bioethanol; Biorefinery; Enzyme complex; Miscanthus sinensis; Pichia pastoris