title: Enzymatic hydrolysis of hardwood and softwood harvest residue fibers released by sulfur dioxide-ethanol-water fractionation.
abstract: The enzymatic hydrolysis of hardwood and softwood harvest residues treated by SO2-ethanol-water (SEW) fractionation was studied. The target was to convert these fibers with high yield into glucose monomers which could be further converted into biofuel by a subsequent fermentation stage. Hardwood biomass residues were efficiently digested at low enzyme dosage (5 FPU/g cellulose) whereas the softwood residues required notably higher enzyme dosage (20 FPU) for sufficient conversion. However, cellulase dosage of softwood could be reduced mannanase supplementation. Especially the high lignin content of softwood biomass pulps impairs the digestibility and thereby, improved delignification could notably enhance the hydrolysis yields. It was shown that inferior delignification of SW biomass is due to persistent polyphenolic acids present in coniferous bark, whereas no evidence of the negative effect of inorganics and acetone extractives was observed. Additionally, SW hydrolyzate was successfully converted into a mixture of butanol, acetone and ethanol through ABE fermentation.
authors.affiliation: Department of Forest Products Technology, Aalto University, FI-00076 AALTO, Finland. Electronic address: minna.yamamoto@aalto.fi.
authors.forename: Minna
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Forest Products Technology, Aalto University, FI-00076 AALTO, Finland.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Iakovlev
authors.affiliation: Department of Biotechnology and Chemical Technology, Aalto University, FI-00076 AALTO, Finland.
authors.forename: Sandip
authors.initials: S
authors.lastname: Bankar
authors.affiliation: Department of Chemical and Biological Engineering, University of Maine, 5737 Jenness Hall, Orono, ME 04469-5737, USA.
authors.forename: Mehmet Sefik
authors.initials: MS
authors.lastname: Tunc
authors.affiliation: Department of Forest Products Technology, Aalto University, FI-00076 AALTO, Finland; Department of Chemical and Biological Engineering, University of Maine, 5737 Jenness Hall, Orono, ME 04469-5737, USA. Electronic address: AvanHeiningen@umche.maine.edu.
authors.forename: Adriaan
authors.initials: A
authors.lastname: van Heiningen
mesh_terms: D018533:Biomass; D002480:Cellulase / Q000378:metabolism*; D005591:Chemical Fractionation; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D006868:Hydrolysis; D008031:Lignin / Q000302:isolation & purification; D008361:Mannosidases / Q000378:metabolism; D059808:Polyphenols / Q000494:pharmacology; D012972:Sodium Hydroxide / Q000494:pharmacology; D013458:Sulfur Dioxide / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D014934:Wood / Q000378:metabolism*
chemical_list: D059808:Polyphenols; D014867:Water; D013458:Sulfur Dioxide; D000431:Ethanol; D012972:Sodium Hydroxide; D008031:Lignin; D008361:Mannosidases; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases
keywords: ABE fermentation; Biorefinery; Enzymatic hydrolysis; Harvest residue; SO(2)–ethanol–water (SEW) fractionation