INVOLVEMENT IN SOFT-ROT WOOD DECAY AND APPLICATION OF LACCASE

本研究探讨了漆酶在软腐木材腐烂过程中的可能作用，并从软腐后菌Graphium sp.M-1-9.1培养物中检测了漆酶的理化性质。选择了对日本山毛榉木降解效果显著、产漆酶活性高的软腐后菌grapum sp. M-1-9。这种真菌生长在邓肯的培养基上，培养基中含有小木片。提取培养滤液，得到硫酸铵沉淀。样品采用Phenyl Sepharose， DEAE Sephaose Cl-6B和Hi Load 16/10 Phenyl Sepharose HP柱层析进行纯化。采用SDS-PAGE和Superdex 75 PC 3.2/30.4凝胶过滤检测两个条带。测定了部分纯化漆酶氧化几种底物的动力学参数。部分纯化漆酶的最适pH为4.5.5。从真菌培养物中分离出低分子量物质，该物质催化氧和电子供体之间的氧化还原反应产生羟基自由基。低分子量物质与漆酶协同产生的羟基自由基可能在软腐木和白腐木的腐烂过程中起重要作用。

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.