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

近年来，在日本，农田、高尔夫球场等地使用的农药造成的环境污染已成为严重的社会问题。由于农田和高尔夫球场与水系（即河流和湖泊）紧密相连，农用化学品会造成水污染，并对自然水生态系统产生不良影响。为了防止农药对水体的污染，利用微生物直接处理含有农药的土壤似乎是最有效的方法之一。在本研究中，培养条件下有效生产的木质素降解酶的固定化细胞培养，使用白腐真菌，Pleumorostreatus，和处理农药，2，4-D和2，4，5-T，木质素降解酶进行了检查。以聚氨酯泡沫塑料（PUF）为载体，研究了白腐菌平菇（Pleenostreatus）产木质素降解酶锰过氧化物酶（MnP）和漆酶（Lac）的情况。在pH4.5、温度30℃、葡萄糖浓度20 g/l、PUF数40个条件下，两种酶的最大活力分别为500和80 U/ml。培养50 h时，糙皮侧耳酶解液对农药2，4-D和2，4，5-T的去除率约为50%，培养30 h时，糙皮侧耳、黄孢原毛平革菌和B.adusta的混合酶解液对农药2，4-D和2，4，5-T的去除率约为70%。

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.