The Role of Glycosides Formation on the Degradation of Lignin by Wood-Rotting Fungi.

为了阐明碳水化合物组分在木质素生物降解过程中的作用，研究了木质素模型化合物和DHP木质素的转化过程。结果如下：（1）木腐真菌（黄孢原毛革菌、杂色革盖菌和沼泽酪菌）对起始木质素模型化合物（4-乙基辛基甘油-辛基醚、藜芦醇、香草醇和藜芦醛）的消耗速率与碳水化合物培养基的种类有关。模型化合物消耗速率的大小顺序为：多糖培养基（木聚糖、综纤维素）二糖培养基（纤维二糖）单糖培养基（葡萄糖、木糖）。(2)在多糖和双糖培养基中，模型化合物被木腐真菌通过糖诱导的糖苷酶转糖基化作用转化为糖苷。在木聚糖和桦木综纤维素培养基中，藜芦醇在培养早期转化为藜芦基-D-木糖苷。在纤维二糖培养基中，香草醇和藜芦醇分别转化为香草基-D-葡萄糖苷和藜芦基-D-葡萄糖苷。(3)木质素模型化合物对真菌的毒性因糖苷的形成而降低。酚类模型化合物被漆酶或木质素过氧化物酶聚合时，糖苷的形成减少了聚合。(4)采用酶法合成了DNP木质素葡萄糖苷。用木质素过氧化物酶/ H_2O_2孵育DHP木质素-葡萄糖苷，虽然能使DHP木质素发生聚合，但仍能部分解聚。

In order to clarify the role of carbohydrates components on the biodegradation of lignin in wood, the transformation of lignin model compounds and DHP lignin was studied. The results are as follows;(1)(1) The rate of the consumption of the starting lignin model compounds (4-ethylsyringylglycerol- -syringyl ether, veratryl alcohol, vanillyl alcohol and veratrum aldehyde) by wood-rotting fungi (Phanerochaete chrysosporium, Coriolus versicolor and Tyromyces palustris) dependedon the kind of carbohydrate media. The order of the rate of the modelcompounds consumption was, polysaccharide medium(xylan, holocellulose) disaccharide medium (cellobiose ) monosaccharide medium (glucose,xylose).(2) In the polysaccharide and the disaccharide medium, model compounds were transformed into their glycosides by the transglycosy-lation of glycosidase induced by carbohydrates with wood-rotting fungi. In the xylan and birch holocellulose medium, veratryl alcohol was transformed into veratryl -D-xyloside during the early phase of cultivation. In the cellobiose medium, vanillyl alcohol and veratryl alcohol were biotransformed into vanillyl -D-glucoside and veratryl -D-glucoside, respectively.(3) The toxicity of lignin model compounds against fungus was reduced by the formation of their glycosides. The polymerization of phenolic model compounds by laccaseor lignin peroxidase was reduced by the formation of their glycosides.(4) DNP lignin-glucoside was synthesized by an enzymatic method. Incubation of DHP lignin-glucoside with lignin peroxidase / H_2O_2 resulted in partial depolymerization, although treatment of DHP ligninwith them caused polymerization.