LACCASE, CELLULASE AND XYLANASE ACTIVITIES DURING GROWTH OF PLEUROTUS-SAJOR-CAJU ON SAGO HAMPAS

Sage hampas, the fibrous pith residue left after starch extraction fro m sage palm, is abundant at sage-processing factories and can be used as a substrate for the production of laccase by solid substrate fermen tation (SSF) with Pleurotus sajor-caju, an edible mushroom. The fungus grown on hampas with an adjusted carbon:nitrogen ratio of 35:1, exhib ited high laccase activity together with variable cellulase (0.3-2.8 U /g) and xylanase (0.9-10.1 U/g) activity. The maximum amount of laccas e produced was approximately 17.7 U/g after 6 days of SSF using 4-week -old inoculum at a density of 10%. With the mature four-week inoculum, laccase activity increased 12-fold compared to that achieved with two -week-old inoculum. The optimum pH and temperature of the crude laccas e were 6.0 and 50 degrees C, respectively. The apparent K-m and V-max values obtained were 0.073 mM and 0.962 U/min, respectively. The maxim um laccase activity could be almost doubled after 6 days of fermentati on by addition of 0.2 mM vanillin or ferulic acid; the cellulose to li gnin ratio increased significantly during the 12 days of SSF, from 2.7 4 in the control to 3.3, when 0.2 mM of either vanillin or ferulic aci d was added to the substrate.