Lignin depolymerase catalyzed biobleaching of softwood kraft pulp

A crude enzyme preparation has been isolated from the white-rot fungus Trametes cingulata that depolymerizes high molecular weight softwood kraft lignin components completely. A single treatment with partially purified extracellular T. cingulata culture solution in the presence of similar to 10(4) M FAD, when followed by a brief extraction with dilute aqueous NaOH at ambient temperatures, engenders a 50% reduction in the kappa number of Jack pine kraft pulp brownstock. Thus the lignin depolymerase from T. cingulata appears to be well suited to delignifying unbleached softwood kraft pulp directly.