Characterization of lignin by 1H and 13C NMR spectroscopy

Chen, Chen-Loung; Robert, D.

doi:10.1016/0076-6879(88)61017-2

Cited by 93 publications

(85 citation statements)

References 21 publications

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“…Table 3 lists the corresponding peak assignments identified for the lignin preparations (21,22). The 13 C NMR spectra can be broken into structural unit regions and integrated to obtain structural information.…”

Section: Resultsmentioning

confidence: 99%

Solution-State Nuclear Magnetic Resonance Study of the Similarities between Milled Wood Lignin and Cellulolytic Enzyme Lignin

Holtman

Chang

Kadla

2004

J. Agric. Food Chem.

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The structures of milled wood lignin (MWL) and cellulolytic enzyme lignin (CEL) have been analyzed using traditional chemical methods and solution-state NMR techniques. Comparisons of the results obtained reveal that subtle differences exist between the two lignin preparations. Thioacidolysis produced higher monomer yields from CEL than MWL, suggesting MWL has a more condensed structure. Quantitative (13)C NMR determined the degree of condensation in MWL to be 0.43 unit per aromatic moiety as compared to 0.36 in CEL. The MWL also contained a lower amount of beta-O-4' substructures per aromatic ring than CEL, 0.41 versus 0.47, respectively. Carbohydrate analysis revealed that the MWL may contain a higher proportion of middle lamella material as compared to the CEL. Because the middle lamella is considered to have a more condensed lignin structure, on the basis of the bulk polymerization theory, these results could explain the differences in beta-O-4' and degree of condensation.

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Section: Resultsmentioning

confidence: 99%

Solution-State Nuclear Magnetic Resonance Study of the Similarities between Milled Wood Lignin and Cellulolytic Enzyme Lignin

Holtman

Chang

Kadla

2004

J. Agric. Food Chem.

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“…4 and Table 2. Although some of these signals are not completely resolved, the integration of 1 H-NMR regions has long been applied to estimate the degree of aromatic-ring substitution and the contents of lignin-functional groups, such as aromatic and aliphatic hydroxyls, methoxyls, and ␤-O-4 structures (3,12,13,22). Quantitative estimates were made by correlating the total integral values with the number of protons per C 9 unit in each MWL.…”

Section: Resultsmentioning

confidence: 99%

Structural Characterization of Lignin during Pinus taeda Wood Treatment with Ceriporiopsis subvermispora

Guerra¹,

Mendonça²,

Ferraz³

et al. 2004

Appl Environ Microbiol

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Although lignin is recalcitrant, some specialized fungi developed the ability to degrade this complex molecule. Most of these fungi belong to the basidiomycetes and are responsible for the white-rot decay process (19). White-rot fungi use an intricate oxidative complex to degrade lignin, which is based on oxidative enzymes and low-molecular-mass mediators (28). Several white-rot fungi produce a lignin peroxidase (LiP) that can initiate one-electron oxidation of nonphenolic arylglycerol-␤-O-aryl ether units. This oxidation is followed by C␣-C␤ or ␤-O-aryl cleavage to give aromatic aldehydes or phenylglycerols, respectively, as primary products (19). On the other hand, some white-rot fungi degrade lignin efficiently without producing LiP (20). One of them, Ceriporiopsis subvermispora, has been extensively studied (15,16,17,31,32), owing to its suitability for biopulping (1,27). Although the industrial applicability of this fungus has been recognized, its ligninolytic strategies are not completely understood. It has often been assumed that lignin degradation by C. subvermispora is dependent on manganese-dependent peroxidases and laccases (28). The occurrence of lignin degradation inside the wood matrix during the first stages of wood decay, when low cell wall permeability does not permit enzyme diffusion, has clearly indicated that some low-molecular-mass agents also act in the early stages of lignin biodegradation (2). Lipid peroxidation induced by manganese-dependent peroxidase has been proposed for lignin biodegradation by C. subvermispora (6,17,18,32). Studies with lignin model compounds have shown that nonphenolic arylglycerol-␤-O-aryl units are disrupted by means of one-electron oxidation mechanisms similar to the routes proposed for basidiomycetes that produce LiP (18,32).Under solid-state fermentation of wood, C. subvermispora extensively depolymerizes lignin. Lignin depolymerization has been demonstrated in studies based on the molecular mass distribution of milled wood lignins (MWLs) recovered from biotreated wood samples (15) and in studies using in situ derivatization followed by reductive cleavage (DFRC) of lignin in biotreated wood, which indicates lignin depolymerization as a consequence of aryl-ether degradation (16).The present study provides additional data for evaluating lignin biodegradation by C. subvermispora during solid-state fermentation of Pinus taeda wood. The structural characteristics of MWLs extracted from sound (untreated) and biotreated wood samples were elucidated using wet-chemical and spectroscopic analyses. MATERIALS AND METHODSFungus, inoculum preparation, and wood biodegradation. C. subvermispora (Pilat) Gilbertson et Ryvarden cultures were maintained on 2% (wt/vol) malt extract agar plates at 4°C. The wood chips (approximately 2.5 by 1.2 by 0.2 cm) used in this work came from a single log of a 28-year-old P. taeda tree.Biodegradation experiments were carried out in 20-liter polypropylene bioreactors. Precolonized wood chips were used as inoculum seed to start the colonization ...

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“…To obtain a soluble sample for GPC and NMR spectroscopy, lignin was acetylated by the method of Chen and Robert (1988).…”

Section: Acetylated Ligninmentioning

confidence: 99%

A method for isolation of milled-wood lignin involving solvent swelling prior to enzyme treatment

et al. 1995

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involvingSummary A new lignin isolation method has been developed. Wood and pulp were subjected to ball milling, swelled in an organic solvent, and then treated with a cellulase. The enzyme digestion time could be shortened to 1 day with this method. The lignin obtained has been named Swelled Enzyme Lignin (SEL). Swelling and enzyme digestion conditions and their effects on lignins were investigated. The SEL's from wood could be directly washed with water, while those from pulp had to be washed with aqueous acetic acid because they were water soluble. The purification of crude SEL's was accomplished by extracting them with dioxane-water, and then precipitating and washing with ethyl ether. Lignin yields were 24-67% based on the total amount of lignin present. The characteristics of the SEL's were further investigated by gel-permeation chromatography (GPC), infrared and 13C nuclear magnetic resonance (NMR) spectroscopy.

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Characterization of lignin by 1H and 13C NMR spectroscopy

Cited by 93 publications

References 21 publications

Solution-State Nuclear Magnetic Resonance Study of the Similarities between Milled Wood Lignin and Cellulolytic Enzyme Lignin

Solution-State Nuclear Magnetic Resonance Study of the Similarities between Milled Wood Lignin and Cellulolytic Enzyme Lignin

Structural Characterization of Lignin during Pinus taeda Wood Treatment with Ceriporiopsis subvermispora

A method for isolation of milled-wood lignin involving solvent swelling prior to enzyme treatment

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