title: Increased saccharification yields from aspen biomass upon treatment with enzymatically generated peracetic acid.
abstract: The recalcitrance of lignocellulosic biomass to enzymatic release of sugars (saccharification) currently limits its use as feedstock for biofuels. Enzymatic hydrolysis of untreated aspen wood releases only 21.8% of the available sugars due primarily to the lignin barrier. Nature uses oxidative enzymes to selectively degrade lignin in lignocellulosic biomass, but thus far, natural enzymes have been too slow for industrial use. In this study, oxidative pretreatment with commercial peracetic acid (470 mM) removed 40% of the lignin (from 19.9 to 12.0 wt.% lignin) from aspen and enhanced the sugar yields in subsequent enzymatic hydrolysis to about 90%. Increasing the amount of lignin removed correlated with increasing yields of sugar release. Unfortunately, peracetic acid is expensive, and concentrated forms can be hazardous. To reduce costs and hazards associated with using commercial peracetic acid, we used a hydrolase to catalyze the perhydrolysis of ethyl acetate generating 60-70 mM peracetic acid in situ as a pretreatment to remove lignin from aspen wood. A single pretreatment was insufficient, but multiple cycles (up to eight) removed up to 61.7% of the lignin enabling release of >90% of the sugars during saccharification. This value corresponds to a predicted 581 g of fermentable sugars from 1 kg of aspen wood. Improvements in the enzyme stability are needed before the enzymatically generated peracetic acid is a commercially viable alternative.
authors.affiliation: Department of Bioproducts and Biosystems Engineering, 2004 Folwell Avenue, Saint Paul, MN, 55108-6128, USA.
authors.forename: Shona
authors.initials: S
authors.lastname: Duncan
authors.forename: Qing
authors.initials: Q
authors.lastname: Jing
authors.forename: Adrian
authors.initials: A
authors.lastname: Katona
authors.forename: Romas J
authors.initials: RJ
authors.lastname: Kazlauskas
authors.forename: Jonathan
authors.initials: J
authors.lastname: Schilling
authors.forename: Ulrike
authors.initials: U
authors.lastname: Tschirner
authors.forename: Waleed Wafa
authors.initials: WW
authors.lastname: Aldajani
mesh_terms: D018533:Biomass; D002241:Carbohydrates / Q000096:biosynthesis*; D004950:Esterases / Q000378:metabolism*; D006868:Hydrolysis / Q000187:drug effects; D008031:Lignin / Q000032:analysis; D010463:Peracetic Acid / Q000494:pharmacology*; D032107:Populus / Q000187:drug effects* / Q000378:metabolism*; D012972:Sodium Hydroxide / Q000494:pharmacology; D014934:Wood / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D012972:Sodium Hydroxide; D008031:Lignin; D004950:Esterases; D010463:Peracetic Acid