Production of manganese peroxidase from fungal isolate CPN01 and their in vitro bleaching-ability on kraft pulp

In the framework of development of biopulping and biobleaching, utilization of several fungal isolates obtained from Indonesian forest has been investigated. This work deals with production of manganese peroxidase (MnP) secreted by fungal isolate CPN01 and its application to in vitro bleaching of Kraft pulp. Production of MnP was carried out on liquid media with various nutrients. Different kinds of nitrogen source (polypepton), carbon sources (glucose and sucrose) and wheat bran extracts were used. Influence of temperature on the MnP production was also studied. The crude enzyme was used for bleaching Kraft pulp in combination with alkaline extraction. Influence of mediator during enzymatic bleaching was also observed. The experimental results showed that concentration of polypepton as nitrogen source influenced significantly on the production of MnP. The highest MnP activity (16 units/flask) was observed in the cultivation of CPN01 in a liquid medium in which the wheat bran extract was added. Cultivation of CPN01 at 37 deg. C resulted in a higher MnP-activity compared with those at 30 deg. C. In vitro bleaching-experiment indicated that MnP from CPN01 reduced kappa number and increase brightness of pulp. The mediator, pulp consistency and pH of alkaline extraction have a significantly influence on the reducing of kappa number. Two steps in vitro bleaching with crude enzyme of MnP from CPN01 combined with two steps alkaline extraction reduced kappa number of Kraft pulp up to 12.2 point. The weight lost of pulp was around 5 percent. An increase in brightness of pulp up to 69 percent was observed, while unbleached Kraft pulp had a brightness of 54 percent