title: Fractionation of cellulase and fermentation inhibitors from steam pretreated mixed hardwood.
abstract: The purpose of liquid hot water and steam pretreatment of wood is to fractionate hemicelluloses, partially solubilize lignin, and enhance enzyme hydrolysis of cellulose. The pretreatment also solubilizes sugar oligomers, lignin-derived phenolic compounds, acetic acid, and furan derivatives that inhibit cellulase enzymes and/or impede fermentation of hydrolysates by yeasts. This work extends knowledge of the relative contribution of identified inhibitors, and the effect of temperature on their release when pretreated materials are washed and filtered with hot water. Dramatic yield improvements occur when polymeric or activated carbon adsorbs and removes inhibitors. By desorbing, recovering, and characterizing adsorbed molecules we found phenolic compounds were strong inhibitors of enzyme hydrolysis and fermentation of concentrated filtrates by Saccharomyces cerevisiae wine yeast NRRL Y-1536 or xylose fermenting yeast 424A (LNH-ST). These data show that separation of inhibitors from pretreatment liquid will be important in achieving maximal enzyme activity and efficient fermentations.
authors.affiliation: Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2022, USA.
authors.forename: Youngmi
authors.initials: Y
authors.lastname: Kim
authors.forename: Thomas
authors.initials: T
authors.lastname: Kreke
authors.forename: Rick
authors.initials: R
authors.lastname: Hendrickson
authors.forename: Josh
authors.initials: J
authors.lastname: Parenti
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ladisch
mesh_terms: D000180:Acrylic Resins / Q000494:pharmacology; D000327:Adsorption / Q000187:drug effects; D002480:Cellulase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D005591:Chemical Fractionation / Q000379:methods*; D004791:Enzyme Inhibitors / Q000302:isolation & purification*; D005285:Fermentation / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism; D006868:Hydrolysis / Q000187:drug effects; D010636:Phenols / Q000302:isolation & purification; D011137:Polystyrenes / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D012997:Solvents / Q000737:chemistry; D013227:Steam; D013997:Time Factors; D014934:Wood / Q000737:chemistry* / Q000201:enzymology*
chemical_list: D000180:Acrylic Resins; D004791:Enzyme Inhibitors; D010636:Phenols; D011137:Polystyrenes; D012997:Solvents; D013227:Steam; C015661:amberlite XAD 7; D002482:Cellulose; D002480:Cellulase; D005947:Glucose