Bleaching of hardwood kraft pulp with manganese peroxidase from Phanerochaete sordida YK-624 without addition of MnSO4

A study was conducted on the bleaching of kraft pulp with manganese peroxidase (MnP) from the Phanerochaete sordida YK-624 fungus without the addition of MnSO4. Oxalate was used as the Mn3+-chelating and reductive agent. Results showed that oxalate facilitates the bleaching of the kraft pulp with MnP by effectively using manganese originally found in the pulp. The oxidation of Mn2+ by MnP was found to be dependent on the presence of organic acids produced by the fungus.