Time course of fungal removal of lipophilic extractives from Eucalyptus globulus wood

Free and esterified sitosterol, the main lipophilic constituents of eucalyp t wood extractives, have been associated with the formation of pitch deposi ts during manufacturing of environmentally-sound paper pulp from Eucalyptus globulus wood. These, and other lipophilic compounds, were analyzed by gas chromatography-mass spectrometry in the course of wood treatments (up to 7 weeks) with four extractive-degrading fungi in order to optimize biotechno logical control of pitch deposition in eucalypt pulp (with moderate loss of wood weight). In contrast to commercialized fungi used in pitch control, w hich are not able to degrade sitosterol, the fungi investigated in this pap er produced a rapid decline of both free and esterified sterols in wood. Th e degradation rate of steroid hydrocarbons and squalene was moderate, and t he amount of steroid ketones (probably formed during oxidative degradation of steroids) and triglycerides increased at different stages of wood treatm ent. Up to 95% removal of total steroids (including free and esterified ste rols, steroid ketones and steroid hydrocarbons) by fungi was obtained at th e end of wood treatment under the solid-state fermentation conditions used. The most promising results from the point of view of industrial applicabil ity, however, were obtained after 1-2 weeks of treatment with either Phlebi a radiata or Par ia subvermispora, which enabled 70% steroid removal with a moderate wood weight loss of 1-4%. (C) 2000 Elsevier Science B.V. All righ ts reserved.