Fungal degradation of lipophilic extractives in Eucalyptus globulus wood

Solid-state fermentation of eucalypt wood with several fungal strains was i nvestigated as a possible biological pretreatment for decreasing the conten t of compounds responsible for pitch deposition during Cl-2-free manufactur e of paper pulp. First, different pitch deposits were characterized by gas chromatography (GC) and GC-mass spectrometry (MS), The chemical species ide ntified arose from lipophilic wood extractives that survived the pulping an d bleaching processes, Second, a detailed GC-MS analysis of the lipophilic fraction after fungal treatment of wood was carried out, and different degr adation patterns were observed, The results showed that some basidiomycetes that decreased the lipophilic fraction also released significant amounts o f polar extractives, which were identified by thermochemolysis as originati ng from lignin depolymerization. Therefore, the abilities of fungi to contr ol pitch should be evaluated after analysis of compounds involved in deposi t formation and not simply by estimating the decrease in the total extracti ve content. In this way, Phlebia radiata, Funalia trogii, Bjerkandera adust a, and Poria subvermispora strains were identified as the most promising or ganisms for pitch biocontrol, since they degraded 75 to 100% of both free a nd esterified sterols, as well as other lipophilic components of the eucaly pt wood extractives, Ophiostoma piliferum, a fungus used commercially for p itch control, hydrolyzed the sterol esters and triglycerides, but it did no t appear to be suitable for eucalypt wood treatment because it increased th e content of free sitosterol, a major compound in pitch deposits.