title: The influence of pretreatment and enzyme loading on the effectiveness of batch and fed-batch hydrolysis of corn stover.
abstract: To try to improve hydrolysis yields at elevated solids loadings, a comparison was made between batch and fed-batch addition of fresh substrate at the initial and later phases of hydrolysis. Both ethanol (EPCS) and steam-pretreated corn stover (SPCS) substrates were tested at low (5 FPU) and high (60 FPU) loadings of cellulase per gram of cellulose. The fed-batch addition of fresh substrate resulted in a slight decrease in hydrolysis yields when compared with the corresponding batch reactions. A 72-h hydrolysis of the SPCS substrate resulted in a hydrolysis yield of 66% compared with 51% for the EPCS substrate. When the enzyme adsorption and substrate characteristics were assessed during batch and fed-batch hydrolysis, it appeared that the irreversible binding of cellulases to the more recalcitrant original substrate limited their access to the freshly added substrate. After 72-h hydrolysis of the SPCS substrate at low enzyme loadings, ∼40-50% of the added cellulases were desorbed into solution, whereas only 20% of the added enzyme was released from the EPCS substrate. Both simultaneous and sequential treatments with xylanases and cellulases resulted in an up to a 20% increase in hydrolysis yields for both substrates at low enzyme loading. Simons' stain measurements indicated that xylanase treatment increased cellulose access, thus facilitating cellulose hydrolysis.
authors.affiliation: Forest Products Biotechnology Group, Dept. of Wood Science, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. richard.chandra@ubc.ca
authors.forename: Richard P
authors.initials: RP
authors.lastname: Chandra
authors.forename: Kathy
authors.initials: K
authors.lastname: Au-Yeung
authors.forename: Carolina
authors.initials: C
authors.lastname: Chanis
authors.forename: Alexandra A
authors.initials: AA
authors.lastname: Roos
authors.forename: Warren
authors.initials: W
authors.lastname: Mabee
authors.forename: Pablo A
authors.initials: PA
authors.lastname: Chung
authors.forename: Sonia
authors.initials: S
authors.lastname: Ghatora
authors.forename: Jack N
authors.initials: JN
authors.lastname: Saddler
mesh_terms: D004798:Enzymes / Q000378:metabolism*; D006868:Hydrolysis; D003313:Zea mays / Q000378:metabolism*
chemical_list: D004798:Enzymes