Title: Modification of the nanostructure of lignocellulose cell walls via a non-enzymatic lignocellulose deconstruction system in brown rot wood-decay fungi

Abstract

Wood decayed by brown rot fungi and wood treated with the chelator-mediated Fenton (CMF) reaction, either alone or together with a cellulose enzyme cocktail, was analyzed by small angle neutron scattering (SANS), sum frequency generation (SFG) spectroscopy, Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Results showed that the CMF mechanism mimicked brown rot fungal attack for both holocellulose and lignin components of the wood. Crystalline cellulose and lignin were both depolymerized by the CMF reaction. Porosity of the softwood cell wall did not increase during CMF treatment, enzymes secreted by the fungi did not penetrate the decayed wood. The enzymes in the cellulose cocktail also did not appear to alter the effects of the CMF-treated wood relative to enhancing cell wall deconstruction. This suggests a rethinking of current brown rot decay models and supports a model where monomeric sugars and oligosaccharides diffuse from the softwood cell walls during non-enzymatic action. In this regard, the CMF mechanism should not be thought of as a “pretreatment” used to permit enzymatic penetration into softwood cell walls, but instead it enhances polysaccharide components diffusing to fungal enzymes located in wood cell lumen environments duringmore » decay. SANS and other data are consistent with a model for repolymerization and aggregation of at least some portion of the lignin within the cell wall, and this is supported by AFM and TEM data. The data suggest that new approaches for conversion of wood substrates to platform chemicals in biorefineries could be achieved using the CMF mechanism with >75% solubilization of lignocellulose, but that a more selective suite of enzymes and other downstream treatments may be required to work when using CMF deconstruction technology. Strategies to enhance polysaccharide release from lignocellulose substrates for enhanced enzymatic action and fermentation of the released fraction would also aid in the efficient recovery of the more uniform modified lignin fraction that the CMF reaction generates to enhance biorefinery profitability.« less

Authors:

Goodell, Barry ;

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Zhu, Yuan; Kim, Seong; Kafle, Kabindra; Eastwood, Daniel; Daniel, Geoffrey; Jellison, Jody; Yoshida, Makoto; Groom, Leslie; Pingali, Sai Venkatesh; O’Neill, Hugh

Publication Date:

Tue Jul 11 00:00:00 EDT 2017

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Lignocellulose Structure and Formation (CLSF)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1618685

Alternate Identifier(s):

OSTI ID: 1389009

Grant/Contract Number:  

IPTS-12345/CG-3; SC0001090; FWP ERKP752; FWP ERKP291

Resource Type:

Published Article

Journal Name:

Biotechnology for Biofuels

Additional Journal Information:

Journal Name: Biotechnology for Biofuels Journal Volume: 10 Journal Issue: 1; Journal ID: ISSN 1754-6834

Publisher:

Springer Science + Business Media

Country of Publication:

Netherlands

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; 09 BIOMASS FUELS; biofuels (including algae and biomass), bio-inspired, membrane, carbon sequestration, materials and chemistry by design, synthesis (self-assembly)