title: Multifunctional Cellulolytic Enzymes Outperform Processive Fungal Cellulases for Coproduction of Nanocellulose and Biofuels.
abstract: Producing fuels, chemicals, and materials from renewable resources to meet societal demands remains an important step in the transition to a sustainable, clean energy economy. The use of cellulolytic enzymes for the production of nanocellulose enables the coproduction of sugars for biofuels production in a format that is largely compatible with the process design employed by modern lignocellulosic (second generation) biorefineries. However, yields of enzymatically produced nanocellulose are typically much lower than those achieved by mineral acid production methods. In this study, we compare the capacity for coproduction of nanocellulose and fermentable sugars using two vastly different cellulase systems: the classical "free enzyme" system of the saprophytic fungus, Trichoderma reesei (T. reesei) and the complexed, multifunctional enzymes produced by the hot springs resident, Caldicellulosiruptor bescii (C. bescii). We demonstrate by comparative digestions that the C. bescii system outperforms the fungal enzyme system in terms of total cellulose conversion, sugar production, and nanocellulose production. In addition, we show by multimodal imaging and dynamic light scattering that the nanocellulose produced by the C. bescii cellulase system is substantially more uniform than that produced by the T. reesei system. These disparities in the yields and characteristics of the nanocellulose produced by these disparate systems can be attributed to the dramatic differences in the mechanisms of action of the dominant enzymes in each system.
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: John M
authors.initials: JM
authors.lastname: Yarbrough
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Ruoran
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Mittal
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Todd
authors.initials: T
authors.lastname: Vander Wall
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Yannick J
authors.initials: YJ
authors.lastname: Bomble
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Decker
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Himmel
authors.affiliation: Biosciences Center, National Renewable Energy Lab , 1503 Denver W. Parkway, Golden, Colorado 80401, United States.
authors.forename: Peter N
authors.identifier: 0000-0003-3360-9210
authors.initials: PN
authors.lastname: Ciesielski
mesh_terms: D056804:Biofuels; D044602:Cellulases / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D000068536:Bacillota / Q000201:enzymology* / Q000254:growth & development; D006868:Hydrolysis; D064251:Multifunctional Enzymes / Q000378:metabolism*; D010316:Particle Size; D013499:Surface Properties; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D056804:Biofuels; D064251:Multifunctional Enzymes; D002482:Cellulose; D044602:Cellulases
keywords: biofuel; cellulase; enzymatic hydrolysis; multifunctional enzyme; nanocellulose