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  • Walter de Gruyter GmbH  (4)
  • English  (4)
  • 1
    Online Resource
    Online Resource
    Sterols and lignin in Eucalyptus globulus Labill. wood: Spatial distribution and fungal removal as revealed by microscopy and chemical analyses
    Walter de Gruyter GmbH ; 2009
    In:  hfsg Vol. 63, No. 3 ( 2009-05-01), p. 362-370
    Details
    In: hfsg, Walter de Gruyter GmbH, Vol. 63, No. 3 ( 2009-05-01), p. 362-370
    Abstract: Wood decay experiments were carried out aiming at the selective removal of lipophilic compounds with selected basidiomycetes isolated from Eucalyptus globulus plantations in Uruguay: Dendrophora albobadia , Lentinus tigrinus , Peniophora cinerea , Peniophora lycii , and Phanerochaete crassa . Localization and composition of lipophilic compounds and lignin of E. globulus were determined by gas chromatography-mass spectrometry, fluorescence microscopy using filipin staining, confocal laser scanning microscopy (CLSM), and low temperature scanning electron microscopy. Free and esterified sterols, mainly sitosterol, were the predominant lipophilic compounds in the control wood. Sterols were present in ray parenchyma cells, together with polyphenols, and in vessels. This confirms earlier observations indicating that these cell types are the principal source of lipophilic extractives involved in pitch problems during pulping and bleaching. Sterols are also present in the vestures of fiber and vessel pits. Different fungal degradation patterns of E. globulus wood were determined. P. lycii showed the highest specificity for lignin degradation during short incubation time together with considerable sterol removal capacity. Ray parenchyma cells and their lumen deposits were strongly degraded by P. lycii . Eucalypt lignin located in vessel walls and fiber cell corners was more resistant to fungal attack, as revealed by CLSM. The initial decay stage of L. tigrinus was restricted to vessels and tyloses where the sterol compounds were removed.
    Type of Medium: Online Resource
    ISSN: 1437-434X , 0018-3830
    URL: Article
    DOI: 10.1515/HF.2009.041
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1466072-6
    SSG: 23
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  • 2
    Online Resource
    Online Resource
    HSQC-NMR analysis of lignin in woody ( Eucalyptus globulus and Picea abies ) and non-woody ( Agave sisalana ) ball-milled plant materials at the gel state 10 th EWLP, Stockholm, Sweden, August 25–28, 2008
    Walter de Gruyter GmbH ; 2009
    In:  hfsg Vol. 63, No. 6 ( 2009-11-01), p. 691-698
    Details
    In: hfsg, Walter de Gruyter GmbH, Vol. 63, No. 6 ( 2009-11-01), p. 691-698
    Abstract: In situ analysis of lignin by 2D NMR of whole plant material was carried out by swelling finely ball-milled samples in deuterated dimethylsulfoxide (DMSO- d 6 ) and sonicated so that a gel was formed in the NMR analysis tube. Solution HSQC NMR spectra of different plant materials representative for hardwood ( Eucalyptus globulus ), softwood ( Picea abies ), and non-woody plants ( Agave sisalana ) are presented here. The spectra show signals corresponding to those of the main plant constituents, such as lignin and polysaccharides. The lignin signals were assigned by comparing the HSQC spectra of the whole plant materials with the HSQC spectra of their respective milled-wood lignins (MWLs). In general terms, the major lignin structural features, such as the relative abundances of the main lignin substructures, the syringyl/guaiacyl ratios and the extent of γ-acetylation of the lignin side-chain observed in the HSQC spectra of the whole plant materials, matched those obtained from the HSQC spectra of the isolated MWLs. Therefore, this technique, which needs only minor amounts of lignocellulosic material and minimal sample preparation, can be useful for the rapid screening of plant lignins without the need for tedious and time-consuming lignin isolation procedures.
    Type of Medium: Online Resource
    ISSN: 1437-434X , 0018-3830
    URL: Article
    DOI: 10.1515/HF.2009.070
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1466072-6
    SSG: 23
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Structural characterization of milled wood lignins from different eucalypt species
    Walter de Gruyter GmbH ; 2008
    In:  hfsg Vol. 62, No. 5 ( 2008-09-01), p. 514-526
    Details
    In: hfsg, Walter de Gruyter GmbH, Vol. 62, No. 5 ( 2008-09-01), p. 514-526
    Abstract: The chemical structure of milled-wood lignins from Eucalyptus globulus , E. nitens , E. maidenii , E. grandis , and E. dunnii was investigated. The lignins were characterized by analytical pyrolysis, thioacidolysis, and 2D-NMR that confirmed the predominance of syringyl over guaiacyl units and only showed traces of p -hydroxyphenyl units. E. globulus lignin had the highest syringyl content. The heteronuclear single quantum correlation (HSQC) NMR spectra yielded information about relative abundances of inter-unit linkages in the whole polymer. All the lignins showed a predominance of β-O-4′ ether linkages (66–72% of total side-chains), followed by β-β′ resinol-type linkages (16–19%) and lower amounts of β-5′ phenylcoumaran-type (3–7%) and β-1′ spirodienone-type linkages (1–4%). The analysis of desulfurated thioacidolysis dimers provided additional information on the relative abundances of the various carbon-carbon and diaryl ether bonds, and the type of units (syringyl or guaiacyl) involved in each of the above linkage types. Interestingly, 93–94% of the total β-β′ dimers included two syringyl units indicating that most of the β-β′ substructures identified in the HSQC spectra were of the syringaresinol type. Moreover, three isomers of a major trimeric compound were found which were tentatively identified as arising from a β-β′ syringaresinol substructure attached to a guaiacyl unit through a 4-O-5′ linkage.
    Type of Medium: Online Resource
    ISSN: 1437-434X , 0018-3830
    URL: Article
    DOI: 10.1515/HF.2008.096
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2008
    detail.hit.zdb_id: 1466072-6
    SSG: 23
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    A commercial laccase-mediator system to delignify and improve saccharification of the fast-growing Paulownia fortunei (Seem.) Hemsl.
    Walter de Gruyter GmbH ; 2018
    In:  Holzforschung Vol. 73, No. 1 ( 2018-12-19), p. 45-54
    Details
    In: Holzforschung, Walter de Gruyter GmbH, Vol. 73, No. 1 ( 2018-12-19), p. 45-54
    Abstract: It was demonstrated for the first time that a laccase-based enzymatic pretreatment is able to delignify fast-growing paulownia species. The treatment was performed with a commercial low-redox potential laccase isolated from Myceliophthora thermophila (Apinis) Oorschot and methyl syringate (MeS) as a natural phenolic mediator. Up to 24% lignin removal was attained by the laccase-MeS treatment (L/MeS), followed by alkaline peroxide extraction in a multistage sequence. The reduction in lignin content was accompanied by a significant improvement in the subsequent enzymatic saccharification, with increases of up to 38% glucose and 34% xylose yields. The structural modifications of the lignin were analyzed in situ by two dimensional-nuclear magnetic resonance (2D-NMR) spectroscopy. A considerable removal of guaiacyl and syringyl lignin units with respect to the carbohydrate signals was visible as well as the cleavage of β- O -4′, β-5′ and β-β′ linkages leading to elevated amounts of C α -oxidized guaiacyl and syringyl units. The presence of oxidized lignin compounds in the filtrates of the enzymatic treatments – such as vanillin, vanillic acid, syringaldehyde and syringic acid – conclusively demonstrates the ability of L/MeS treatment to oxidize and depolymerize the lignin in paulownia wood.
    Type of Medium: Online Resource
    ISSN: 1437-434X , 0018-3830
    URL: Article
    DOI: 10.1515/hf-2018-0095
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 1466072-6
    SSG: 23
    Location Call Number Limitation Availability
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