RICE STRAW DEGRADATION BY WHITE ROT FUNGI AND VARIANCE OF ACTIVITIES OF RELATED ENZYMES

White rot fungi (Pleurotus sp.) strains Z17、921 and 1024 were separately cultivated in the medium of rice straw supplemented with 20% of cottonseed hull. The contents of main chemical constituents in the substrate and activities of cellulases complex and polyphenolase in the culture were determined at different growth stages. The results showed that the contents of cellulose and lignin in the cultural substrate continuously decrease from inoculation to the fruit body formation, whereas the amounts of the moisture and crude protein were increased gradually. The activities of laccase in the culture showed a quick increase during mycelium growth and then decrease. The highest activity of guaiacolase occurred during mycelium growth and fruit body formation, and then decreased or disappeared.