الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The aim of this study is to isolate and identify microorganisms associated with polyethylene and plastic polymers in soil. Polyethylene and plastic are two polymers that have a wide range of applications. They are resistant to degradation and deterioration, causing their accumulation in the environment and causing serious environmental problems. Twenty six fungal isolates were recoverd from benzene station soils, Petroleum refinery area and Botany department, faculty of science, Fayoum University. All tested fungi exhibited lignin peroxidase activities in soil as well as in liquid cultures. Aspergillus niger and Penicillium chrysogenum were superior in ligninolytic enzyme production. Hence, they were chosen for the following studies. For optimization of the production of lignin peroxidase enzyme by the two tested fungi, different aspects were considered like : Temperature, pH , exposure to UV light, moisture, carbon source , nitrogen source, metal salt inhibitors and type of plastic materials. The temperature range from 15 ºC to 45 ºC were tried and the optimum temperature of the two fungi under study were 40 ºC for Penicillium chrysogenum and 35 ºC for A.niger. Maximum enzyme activity was reached at pH
5 and 6 for Penicillium chrysogenum and Aspegillus niger, respectively. The gradual increase in moisture from one to five days led to a high significant increase in the amount of enzyme production, it reached 9.9 units ∕ml and 11.0 units ∕ml for P.chrysogenum and A.niger, respectively after 5 days incubation of plastic materials in moisture content. Increasing exposure to UV light decreasing the enzyme activity of two fungal strains, glucose was the most suitable carbon source for maximum