INVOLVEMENT IN SOFT-ROT WOOD DECAY AND APPLICATION OF LACCASE

本研究探讨了漆酶在软腐木腐烂中的可能作用，并对软腐菌Graphium sp.M-1-9.1培养物中漆酶的理化性质进行了检测。筛选出一株能显著降解日本山毛榉木材并产生高活性漆酶的菌株M-1-9。2.该菌生长在含有小木片的邓肯培养基上。样品经苯基琼脂糖柱层析、DEAE Sephaose CL-6B柱层析和Hi Load 16/10苯基琼脂糖HP柱层析纯化。用SDS-PAGE和Superdex 75 PC 3.2/30.4凝胶过滤对两条带进行了检测，并测定了部分纯化的漆酶氧化几种底物的动力学参数。部分纯化的漆酶的最适pH为4.5.5。从该真菌的培养物中分离到催化氧与电子供体之间的氧化还原反应产生羟基自由基的低分子量物质。这种低分子物质与漆酶结合产生的羟基自由基可能在软腐木材腐烂中起重要作用，就像白腐木材腐烂一样。

The study investigates the possible role of laccase in soft-rot wood decay and examine physical and chemical properties of the enzyme from cultures of soft-rot deuteromycete Graphium sp.M-1-9.1.The soft-rot deuteromycete Graphium sp. M-1-9 which degraded Japanese beech wood significantly and produced laccase with high activity was selected.2.The fungus was grown on Duncan's medium containing small wood pieces. Culture filtrate was extracted and obtained ammonium sulfate precipitates.3.The sample was applied to a Phenyl Sepharose, DEAE Sephaose Cl-6B, and Hi Load 16/10 Phenyl Sepharose HP column chromatographies for purification. The two bands were detected using SDS-PAGE and gel filtration on Superdex 75 PC 3.2/30.4.Kinetic parameters of the partially purified laccase for oxidation of several substrates were determined. The pH optimum for the partially purified laccase was 4.5.5.Low-molecular-weight substance that catalyzes a redox reaction to produce hydroxyl radical between oxygen and electron donors was isolated from cultures of the fungus. Hydroxyl radical produced by the low-molecular-weight substance in concert with laccase may play an important role in soft-rot wood decay as in white-rot wood decay.