Abstract

It has been postulated that in wood inhabiting fungi, iron chelating low molecular weight compounds (siderophore or siderophore-type), would be involved in wood biodegradation. Fungal siderophore from Ganoderma applanatum (FS-Ga) are catecholates and present enzymatic-type activity. In this work, the bleaching of Kraft pulp (Kappa 29.9, viscosity 43.3 mPa. s, brightness 30.4°Elrepho) was carried out by using different sequences including stages with catechol, 2,3-dihydroxybenzoic acid (DHBA) or siderophore extracted from G. applanatum cultures. In the bleaching sequence TpEP with 0.5% catechol, 0.5% DHBA or 0.5% FS-Ga in presence of 0.5% H 2O 2, the kappa number was reduced to 17.7, 16.9 and 18.3 respectively, the viscosity decreased considerably to 12 mPa. s but in the last case the viscosity was 31.3 mPa. s. Using FS-Ga with 0.5% hydrogen peroxide, in the sequence TpEopP, a pulp with kappa number 14, brightness 52°Elrepho and 18.5 mPa. s was obtained.