Exploring the potential of fungal manganese-containing lipoxygenase for pitch control and pulp delignification.

The potential of the lipoxygenase from Gaeumannomyces graminis to remove lipophilic extractives from eucalypt and flax pulps was investigated. Pulp treatments were performed with the lipoxygenase both in the presence and absence of linoleic acid, and were followed by a peroxide bleaching stage. The main lipophilic extractives from eucalypt pulp such as conjugated and free sterols decreased up to 40% and 7%, respectively, by the lipoxygenase treatment in the presence of linoleic acid. Different degradation patterns were observed among the lipophilic compounds present in flax pulp, although a high removal of all the extractives classes, including alkanes (21-55%), fatty alcohols (42-61%), and free (16-55%) and glycosylated (45-71%) sterols, was attained in all the lipoxygenase treatments. Reactions of the lipoxygenase with model lipid mixtures were carried out to better understand the degradation patterns observed in pulps. Finally, pulp delignification by the lipoxygenase treatments was also evaluated.