2D NMR study of lignin modification during pretreatment of Eucalyptus wood feedstock with a fungal laccase and a phenolic mediator
The delignification of eucalypt feedstock during enzymatic pretreatment with the laccase from Myceliophthora thermophila, in conjunction with methyl syringate as mediator, when applied in a multistage sequence consisting of successive enzymatic and alkaline extraction stages, directly on the ground lignocellulosic material was thoroughly studied by two-dimensional nuclear magnetic resonance (2D NMR) of the whole wood (at the gel stage) after each step of the sequence. The 2D NMR analyses of eucalypt feedstock after the enzymatic pretreatment, revealed the removal of guaiacyl and syringyl lignin units (with preferential removal of the former) and aliphatic (mainly beta-O-4'-linked) side-chains of lignin without a substantial change in polysaccharide crosssignals. However, the most noticeable modification was the formation of Calpha-oxidized syringyl lignin units in the enzymatic steps that were partially removed in the alkaline extraction stages. This study revealed that the first cycle of pretreatment of eucalypt with M. thermophila laccase and methyl syringate did not produce any delignification effect and consequently did not increase the saccharification yields. However, at the end of the whole sequence (4 cycles), a high delignification (ca. 50%) of eucalypt feedstock and increases (ca. 40%) in glucose yield after enzymatic hydrolysis was attained with this laccase-mediator pretreatment.
| Main Authors: | , , , , |
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| Format: | capítulo de libro biblioteca |
| Language: | English |
| Published: |
CSIC - Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS)
2014-06-24
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| Subjects: | Eucalyptus wood, Delignification, Enzymatic pretreatment, Laccases, Lignin, 2D NMR, |
| Online Access: | http://hdl.handle.net/10261/98720 |
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