title: Engineered pentafunctional minicellulosome for simultaneous saccharification and ethanol fermentation in Saccharomyces cerevisiae.
abstract: Several yeast strains have been engineered to express different cellulases to achieve simultaneous saccharification and fermentation of lignocellulosic materials. However, successes in these endeavors were modest, as demonstrated by the relatively low ethanol titers and the limited ability of the engineered yeast strains to grow using cellulosic materials as the sole carbon source. Recently, substantial enhancements to the breakdown of cellulosic substrates have been observed when lytic polysaccharide monooxygenases (LPMOs) were added to traditional cellulase cocktails. LPMOs are reported to cleave cellulose oxidatively in the presence of enzymatic electron donors such as cellobiose dehydrogenases. In this study, we coexpressed LPMOs and cellobiose dehydrogenases with cellobiohydrolases, endoglucanases, and β-glucosidases in Saccharomyces cerevisiae. These enzymes were secreted and docked onto surface-displayed miniscaffoldins through cohesin-dockerin interaction to generate pentafunctional minicellulosomes. The enzymes on the miniscaffoldins acted synergistically to boost the degradation of phosphoric acid swollen cellulose and increased the ethanol titers from our previously achieved levels of 1.8 to 2.7 g/liter. In addition, the newly developed recombinant yeast strain was also able to grow using phosphoric acid swollen cellulose as the sole carbon source. The results demonstrate the promise of the pentafunctional minicellulosomes for consolidated bioprocessing by yeast.
authors.affiliation: Metabolic Engineering Research Laboratory, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research, Singapore.
authors.forename: Youyun
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
authors.forename: Tong
authors.initials: T
authors.lastname: Si
authors.affiliation: Metabolic Engineering Research Laboratory, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research, Singapore ang_ee_lui@ices.a-star.edu.sg zhao5@illinois.edu.
authors.forename: Ee Lui
authors.initials: EL
authors.lastname: Ang
authors.affiliation: Metabolic Engineering Research Laboratory, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research, Singapore Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA ang_ee_lui@ices.a-star.edu.sg zhao5@illinois.edu.
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhao
mesh_terms: D002244:Carbon / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D044603:Cellulosomes / Q000235:genetics* / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D000431:Ethanol; D002244:Carbon; D002482:Cellulose