OPTIMIZATION OF MANGANESE PEROXIDASE PRODUCTION BY THE WHITE-ROT FUNGUS BJERKANDERA SP. STRAIN BOS55

Manganese dependent peroxidase (MnP) is the most ubiquitous peroxidase produced by white rot fungi. MnP is known to be involved in lignin de gradation, biobleaching and in the oxidation of hazardous organopollut ants. Bjerkandera sp, strain BOS55 is a nitrogen-unregulated white rot fungus which produces high amounts of MnP in the excess of N-nutrient s due to increased biomass yield. Therefore, the strain is a good cand idate for use in large scale production of this enzyme. The objective of this study was to optimize the MnP production in N-sufficient cultu res by varying different physiological factors such as Mn concentratio n, culture pH, incubation temperature and the addition of organic acid s. The fungus produced the highest level of MnP (up to 900 U l(-1)) wh en the Mn concentration was 0.2 to 1 mM, the pH value was 5.2, and the incubation temperature was 30 degrees C. A noteworthy finding was tha t MnP was also produced at lower levels in the complete absence of Mn. The addition of organic acids like glycolate, malonate, glucuronate, gluconate, 2-hydroxybutyrate to the culture medium increased the peak titres of MnP up to 1250 U l(-1). FPLC profiles indicated that the org anic acids stimulated the production of all MnP isoenzymes present in the extracellular fluid of the fungus.