IMPROVED CONDITIONS FOR BIODELIGNIFICATION OF DEINKED PULP BY ENZYMESFROM PHANEROCHAETE-CHRYSOSPORIUM

Optimum conditions for growth and enzyme production of the white rot f ungus Phanerochaete chrysosporium were studied. Variables investigated included pH, temperature and nutrient concentration, particularly NH4 +. The optimized culture condition was then used for biodelignificatio n of deinked pulp. After 14 days of treatment, the Klason lignin conte nt of deinked pulp was reduced from 18.5 to 12.5%, under shaking condi tions and a pulp consistency of 3%. Reduction in lignin content was co ncurrent with the improvement in strength and water retention value, b ut brightness loss was also observed. The ligninase enzymes obtained f rom a culture 8-12 days old were harvested and applied to a 1% pulp co nsistency together with 0.025-0.4 mM H2O2. Delignification was observe d after 4 days of incubation at 33-degrees, resulting in a pulp having a better brightness retention compared to treatment involving fungal mycelium alone.