Lignin-Degrading Biobleaching of Kraft Pulp, 1994 International Pan Pacific Conference Proceedings

K. Sakai, R. Kondo

A fungal straing, Phanerochaetesordida YK-624 isolated from a rotted wood exhibited a great activity of lignin degradation and kraft pulp bleaching. A membrane filter system was devised to conduct in vitro bleaching with enzymes secreted from fungi. An exponential relationship was observed between the brightness increase of kraft pulp and the activity of manganese peroxide (MnP) secreted from a fungus strain P.sordida YK-624.

Enzyme bleaching of a hardwood unbleached kraft pulp was performed with partly purified manganese peroxidase (MnP) isolated from cultures of P.sordida YK-624. Pulp brightness increased by about 10 points and the kappa number decreased by about 6 points when the kraft pulp was treated with a partly purified MnP in the presence of MnSO4. Tween 80 and sodium malonate with adding H2O2 at a rate of 3 ml/h at 37°C for 24 h. Multiple treatment with MnP provided pulp brightness of 60.2% ISO. The results clearly indicate that MnP is capable of degrading residual lignin in hardwood kraft pulp in vitro.