The potential of using carbohydrate-binding modules (CBMs) for the characterization and modification of cellulose surfaces
department or school: Forestry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Aïssa, Kevin
issued: 2020-02-26T22:26:24Z
issued: 2020
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Cellulose is a structural material that, through its association with lignin and hemicellulose, is recalcitrant to degradation. Although the effectiveness of cellulose hydrolysis is usually assessed via glucose release, typically, cellulase accessibility to the cellulosic substrate is the key limitation that restricts effective enzymatic hydrolysis and has proven much harder to quantify. A novel method, which has the potential to better elucidate the mechanisms involved, involves the use of carbohydrate-binding modules (CBMs). In the work described here, CBM production was optimized, yielding g.L-1 quantities of the specific proteins, which were subsequently used to both characterize the surface morphology of lignocellulosic substrates and functionalize cellulose surfaces. A combination of type A and type B CBMs (CBM2a and CBM17) were primarily employed, as they showed binding preferences towards different morphologies within the cellulosic structure. Compared to more established methods the CBM method more accurately predicted enzyme accessibility, indicating that refining did not significantly improve enzyme accessibility at the microfibril level of the cellulosic substrate. In subsequent work, fluorescence-tagged carbohydrate binding modules (CBMs), which specifically bind to crystalline (CBM2a-RRedX) and paracrystalline (CBM17-FITC) cellulose, were used to differentiate the supramolecular cellulose structures in bleached softwood Kraft fibers during enzyme-mediated hydrolysis. Quantitative image analysis, supported by 13C NMR, SEM imaging, and fiber length distribution analysis, indicated that enzymatic degradation predominated in the more disorganized zones during the initial phase of the hydrolysis reaction. This resulted in rapid fiber fragmentation and an increase in cellulose surface crystallinity. Drying decreased the accessibility of enzymes to these disorganized zones, resulting in a delayed onset of degradation and fragmentation. The use of fluorescence…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/73616
note: The Potential of using Carbohydrate-Binding Modules (CBMs) for the Characterization and Modification of Cellulose Surfaces by Kevin Aïssa B.Sc., Université Paris-V (Descartes), 2010 M. Sc. Université de Sherbrooke, 2013 M. Sc. A. Université de Sherbrooke, 2015 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (FORESTRY) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) February 2020 © Kevin Aïssa, 2020 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: The Potential of using Carbohydrate-Binding Modules (CBMs) for the Characterization and Modification of Cellulose Surfaces submitted by Kevin AÑssa in partial fulfillment of the requirements for the degree of Doctor of philosophy in Forestry Examining Committee: Dr Jack (N) Saddler, Forestry Supervisor Dr. Scott Renneckar, Forestry Supervisory Committee Member Dr. Vikramaditya Yadav, Chemical and Biological Engineering Supervisory Committee Member Dr. Steven Hallam, Microbiology and Immunology University Examiner Dr. Mark Maclachlan, Chemistry University Examiner iii Abstract Cellulose is a structural material that, through its association with lignin and hemicellulose, is recalcitrant to degradation. Although the effectiveness of cellulose hydrolysis is usually assessed via glucose release, typically, cellulase accessibility to the cellulosic substrate is the key limitation that restricts effective enzymatic hydrolysis and has proven much harder to quantify. A novel method, which has the potential to better elucidate the mechanisms involved, involves the use of carbohydrate-binding modules (CBMs). In the work described here, CBM production was optimized, yielding g.L-1 quantities of the specific proteins, which were subsequently used to both characterize the surface morphology of lignocellulosic sub…
has type: Thesis/Dissertation
date issued: 2020-05
is shown at: 10.14288/1.0388734
language: eng
degree discipline: Forestry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/73616