الفهرس 
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Abstract
This work represents the ability of six autochthonous basidiomycetes of Damietta District-Egypt to produce ligninolytic enzymes in comparison with another six basidiomycetes. These fungal strains were first screened for avicellase enzyme, all recorded enzyme activity with Pleurotus columbinus, Cyathus stercoreus exhibited the highest cellulolytic activity. The fungal strains were screened for lignin modifying enzymes based on the decolorization of Poly-R 478. The decolorization of Poly-R varied in prsponse to different nitrogen regims. All tested fungi exhibited decolorization ability without nitrogen except Agaricus campester. Peptone and potassium nitrate stimulated the decolorization potentialities, consequently they have been used at different concentrations by favorable seven fungi that efficiently decolorize Poly-R. All the fungal strains were further screened in different liquid media and peroxidase, laccase, manganese peroxidase (MnP), and lignin peroxidase (LiP) were assayed. Pleurotus columbinus has the highest activity of laccase (0.395 and 5.5 U/ml/min) in both mineral salt malt extract broth (M-M) and vinasse-wheat bran (V-W) . On the other hand Cyathus stercoreus proved to be highest producer of MnP in mineral salt broth (MS) (0.058 U/ml/min). Optimization of both enzymes has been done.The optimum conditions of Pleurotus columbinus laccase were pH 6-6.5 at 30oC for 10-12 days with ammonium tartrate and acetate as a nitrogen sources, arabinose as a carbon source and addition of wheat bran and straw to the culture media. The optimum conditions for MnP production by Cyathus stercoreus were pH 6, 30oC for 14 days, ammonium tartrate, glucose and rice straw. Addition of natural products has a mild effect in production of both enzymes. Both laccase and MnP enhanced by tween 80. Purification was carried out using acetone, ammonium sulfate, Sephadex G-100 and DEAE- sephacel. Maximum activity of purified laccase was recorded at pH 4.5-5, 35oC, 50Mm of 2.6- dimethoxy phenol (2.6-DMP) and it was completely stable at pH 4-5.5 and 35oC. On the other hand the optimum pH, temperature and concentration of both 2.6-DMP & H2O2 for MnP activity were found to be 3.5, 45oC and 0.45 & 0.4 mM respectively and it was completely stable at pH 3.5-4.5 and 45oC. The molecular wheight of purified laccase and MnP by SDS-PAGE was found to be 66 and 37 kDa respectively. Laccase activity was enhanced in presence of Cu2+, Mg2+& Ca2+moreover, Ca2+enhanced MnP activity at the time EDTA caused the highest inhibitory effect for both enzymes.