PRIMARY AND SECONDARY METABOLISMS OF WHITE-POCKET FUNGUS

研究了能够有效、安全地降解环境持久性污染物的催化作用。最近，许多研究小组对白腐担子菌进行了研究，因为只有这种真菌才能使木质素(一种芳香聚合物)完全矿化。然而，强大的木质素降解菌分泌苯酚氧化酶，如漆酶和锰过氧化物酶，这些酶不仅与酚类底物反应，还生成降解产物和聚合产物。在本研究中，目标反应是氯化苯酚的降解，没有任何聚合反应形成氯化芳香聚合物。为了达到这一目的，利用了对木质素降解活性较弱的白腐菌和已知不能降解木质素的褐腐菌。主要研究结果如下：(1)白腐菌Fomitella fraxina在目前所考察的任何条件下，在染料脱色和木质素降解过程中均未产生任何酚氧化酶。(2)在Fomitella fraxina的培养滤液中发现了染料脱色活性。(3)褐腐菌能够通过烷基侧链的氧化还原和芳环的羟化作用使酚类或非酚类单体矿化。(4)褐腐菌不会引起酚类底物的聚合。

Catalysis which could lead to the degradation of environmentally persistent pollutants in an effective and safe manner were researched. Recently, white-rot basidiomycetes have been studied by many research groups since only this type of fungi can cause the complete mineralization of lignin, an aromatic polymer. However, powerful lignin degraders secretes phenol oxidizing enzymes such as laccase and manganese peroxidase, which react with phenolic substrates forming not only degradation products but also polymerized products. In this study, target reaction was degradation of chlorinated phenols without any polymerization reactions forming the chlorinated aromatic polymers. To achieve this, white-rot fungi which show weak actvity against lignin degradation and brown-rot fungi which has been known not to degrade lignin were utilized. Some interesting and unique results are listed below :(1) White-rot fungus, Fomitella fraxinea did not seceretes any phenol oxidases during decolorization of dye and lignin degradation under any conditions examined so far.(2) Dye-decolorization activity was found in the culture filtrate of F.fraxinea.(3) Brown-rot fungi were capable of mineralizing either phenolic or nonphenolic monomers with the oxidation and reduction of alkyl side chain and the hydroxylation of aromatic rings.(4) Brown-rot fungi did not cause polymerization of phenolic substrates.