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Condensed lignin structures and re‐localization achieved at high severities in autohydrolysis of Eucalyptus globulus wood and their relationship with cellulose accessibility
Author(s) -
Araya Fabio,
Troncoso Eduardo,
Mendonça Regis Teixeira,
Freer Juanita
Publication year - 2015
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.25604
Subject(s) - eucalyptus globulus , lignin , cellulose , cellulase , heteronuclear single quantum coherence spectroscopy , hydrolysis , chemistry , biomass (ecology) , ether , cell wall , eucalyptus , substrate (aquarium) , enzymatic hydrolysis , chemical engineering , organic chemistry , materials science , botany , nuclear magnetic resonance spectroscopy , biochemistry , agronomy , biology , ecology , engineering
Eucalyptus globulus wood was subjected to autohydrolysis pretreatment at different severity factors. The pretreated materials were enzymatically saccharified at a substrate load of 10% (w/v) using a cellulase enzyme complex. Around 82–95% of original glucans were retained in the pretreated material, and the enzymatic hydrolysis yields ranged from 58% to 90%. The chemical and structural changes in the pretreated materials were investigated by microscopic (SEM, LSCM) and spectroscopic (2D‐HSQC NMR and FT‐IR) techniques. 2D‐NMR results showed a reduction in the amounts of β‐ O ‐4 aryl–ether linkages and suggested the presence of newly condensed structures of lignin in the biomass pretreated at the more severe conditions. Furthermore, the microscopic analysis showed that lignin migrates out of the cell wall and re‐deposits in certain regions of the fibers at the more severe conditions to form droplet‐like structures and expose the cellulose surface. These changes improved the glucose yield up to 69%, on dry wood basis. Biotechnol. Bioeng. 2015;112: 1783–1791. © 2015 Wiley Periodicals, Inc.