Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Botany - Microbiology

Peroxidases are important group of enzymes that play a major role in biodegradation of organopollutants. Fungi are unique in secreting non- specific; broad-spectrum peroxidases extracellularly. This property makes utilizable tools in biodegradation of organopollutants including textile effluents. The present study focused on screening of indigenous fungal isolates from soil contaminated with textiles effluents for their degradation of different textile dyes and peroxidases production. Eight fungal isolates were isolated, identified, and tested for their peroxidase production and decolorization activity of six different dyes on solid media. Only two dyes (sunzol brilliant orange and suncron blue) were chosen to investigate in liquid media. All fungal isolates gave positive decolorization; however, the highest percentage of decolorization in the liquid media was obtained with humicola grisea. Lignin peroxidases from Humicola grisea, which was the most potent fungus, was studied regarding the optimal culture conditions for production, extraction, purification, characterization of purified isoenzymes. The best lignin peroxidases (LiPs) production obtained using Kirk and Tien media supplemented with 10g l⁻¹ sucrose as carbon source and 0.5g l⁻¹ ammonium hydrogen phosphate as nitrogen source. The optimum temperature for LiPs production was at 30 {u00BA}C, while the optimum pH was at 4. LiPs were extracted and purified using gel filtration and ion exchange chromatography. Protein and heme protein were eluted in different peaks about 6 of these peaks had LiP activity, this is an indication that LiP in H. grisea was isoenzymes

Issued also as CD