Development of Management System for Bioremediation of Contaminated Soil with Agricultural Chemicals by Basidiomycetes

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In recent years, environmental pollution by agricultural chemicals used on farmlands, golf courses, and other areas has been a serious social problem in Japan. Since farmlands and golf courses connect closely with water systems, i.e. rivers and lakes, the agricultural chemicals cause water pollution and provide a bad influence on the natural water ecosystem. In order to prevent water pollution by agricultural chemicals, the direct treatment of soil containing agricultural chemicals using microorganisms seems to be one of the most effective methods. In this research, the incubation condition for efficient production of lignin-degrading enzymes by immobilized cell culture using a white-rot fungus, Pleurotus ostreatus, and the treatment of agricultural chemicals, 2, 4-D and 2, 4, 5-T, by the lignin-degrading enzymes were examined. Production of lignin-degrading enzymes, i.e. manganese peroxidase (MnP) and laccase (Lac), by white-rot fungus Pleurotus ostreatus was studied using polyurethane foam (PUF) as a carrier of immobilizedcells. The maximum activity of the two enzymes was 500 and 80 U/ml, respectively, under incubation conditions such as 40 PUF numbers, pH 4.5, 30℃, and 20 g/l of glucose concentration. Agricultural chemicals, 2, 4-D and 2, 4, 5-T, were decreased by the enzyme solution from P.ostreatus to the extent of about 50% at an incubation time of 50 h and decreased by the mixed enzyme solution from P.ostreatus, B.adusta, and P.chrysosporium to the extent of about 70% at an incubation time of 30 h.