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A new high pressure liquid chromatographic method with evaporative light scattering detection was developed for the qualitative and quantitative analysis of apolar, low molecular weight constituents in wood. The wood extractives were obtained by means of a 6 h Soxhlet extraction with acetone. The extract was quantitatively analysed on an end-capped C18 column eluted with a gradient of acetonitrile:water:acetic acid. The crude sample was directly injected following dissolution in acetonitrile:methanol:dichloromethane (60:8:40) and filtration through a 0.45 ?m membrane filter. No other time consuming fractionation or derivatisation steps were required prior to the analysis. The main apolar, low molecular weight constituents of pinewood are free fatty acids, resin acids, sterols and triglycerides. With this method, individual free fatty acids, sterols and triglycerides are well separated. Resin acids, with the exception of dehydroabietic acid, are not separated and co-elute. The method does not require any sample clean-up steps except filtration and it is compatible with other softwood and hardwood wood species

Ninety wood-inhabiting fungi were screened for their ability to degrade and detoxify acetone extractives in Scots pine (Pinus sylvestris L.) sapwood under solid-state fermentation conditions. Fungal degradation of resin acids and long-chain fatty acids was investigated by high pressure liquid chromatography with evaporative light scattering detection (HPLC-ELSD) and the toxicity of the acetone soluble fraction of wood measured by Microtox assay. Discriminant analysis of data showed different patterns of extractive detoxification for white-rot basidiomycetes and sapstain fungi. The major detoxification skills of basidiomycetes appeared to be related to the highest degradation of resin acids, and particularly dehydroabietic acid. Among them, Ischnoderma benzoinum, Stereum sanguinolentum and Trametes versicolor greatly reduced the sapwood toxicity due to acetone extractives from the EC50 value of 0.08 mg wood ml-1 to levels between 5-10 mg wood ml-1.

1 Division of Wood Science, Sub-department of Forestry, Wageningen Agricultural University, Wageningen, The Netherlands 2 Instituto de Recursos Naturales y Agrobiología (IRNA), Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain, The fungal degradation of lipophilic extractives in sapwood and heartwood from Scots pine (Pinus sylvestris) was studied. In sapwood, the white rot fungi, Bjerkandera sp. and Funalia trogii, removed higher amounts of extractives than the sapstain strains, Ophiostoma ainoae and Ceratocystis allantospora. Triglycerides, long chain fatty acids, steryl esters and waxes in pine sapwood were almost completely degraded by all the fungi. Sterols and resin acids were also extensively degraded by the white rot strains; however, these components were not or only poorly removed by the sapstain fungi. The removal of total extractives by all the fungal strains was higher in sapwood as compared to heartwood. The highly concentrated extractive fraction in pine heartwood mainly consists of resin acids. As observed in sapwood, sapstain were also poorly effective in the degradation of the resin acids present in heartwood. The fungal degradation of heartwood extractives was not only limited by the degradative ability of the various test microorganisms, but also by the inhibitory effect exerted by the extractive fraction. The white rot fungus F. trogii was particularly inhibited on heartwood. Bjerkandera sp. showed a higher tolerance to toxic extractives and was the most efficient fungus in degrading extractive constituents in both Scots pine heartwood and sapwood. Therefore, Bjerkandera sp. strain BOS55 should be considered as a potential agent for pitch control in pulp and paper manufacture., This study has been carried out with financial support from the Commission of the European Communities, Agriculture and Fisheries (FAIR) contract no. CT 95–0560, “Wood extractives in pulp and paper manufacture: technical and environmental implications and biological removal”.

Peroxidases and laccases are key enzymes in the lignin biodegradation process. They oxidize phenolic and non-phenolic lignin model compounds into their phenoxy and cation radicals, respectively. Further non-enzymatic evolution lead then to various C-C and ether bond cleavages. Nevertheless, almost no information on the structural alterations undergone in vitro or in situ by lignin after enzymatic catalysis is available. We report here on the molecular structure of lignin oxidized by various (per)oxidasic systems. The oxidizability of phenolic and non-phenolic structures of the guaiacyl and syringyl type in the lignin network will be discussed as well as the modification of the macromolecular properties of the polymer oxidized in situ or in isolated state.