Degradation of toxic aromatic compounds by basidiomycetes and its application to bioremediation

1. 白腐菌和木质素降解酶对有毒芳香化合物的降解研究双酚A （BPA）是合成聚合物的起始物质，具有内分泌干扰活性。从真菌培养物中纯化的锰过氧化物酶（MnP）也能降解BPA，产生的代谢物被认为是由MnP的单电子氧化机制产生的。4-氯苯二酚被P. ostreatus和其他木质素降解真菌降解。MnP降解2,4-二氯苯酚生成醌，同时从底物中消除氯离子。白腐担子菌对二恶英的降解研究利用木质素降解担子菌MZ-340及其粗酶制剂对二恶英的降解进行了研究。该酶制剂可降低2 ~ 8氯代二恶英的浓度。这种现象被认为是由这种真菌培养中产生的某些蛋白质的捕获效应引起的。用甲苯从污染土壤中提取并吸附在玻璃珠上的二恶英35%被该菌降解。用硅胶柱作为吸附剂，对二恶英的吸附效果可降低80%。酸处理能促进真菌对二恶英的降解。长期固相培养实验表明，在室温下培养360天，二恶英的添加量下降35%。因此，通过混合白腐菌对污染土壤进行简单的处理可用于污染环境的生物修复。

1. Degradation of toxic aromatic compounds by white-rot fungi and ligninolytic enzymesBisphenol A (BPA), which is a starting material of synthetic polymers and has endocrine- disturbing activity, was degraded by the culture of Pleurotus ostreatus. Manganese peroxidase (MnP) purified from the culture of this fungus also degraded BPA to give metabolites which were thought to be produced by one-electron oxidation mechanism of MnP. 4-Chlororezorcinol was degraded by P. ostreatus and other lignin-degrading fungi. MnP degraded 2,4-dichlorophenol to give quinone with concomitant elimination of chloride ion from the substrate.2. Degradation of dioxins by white-rot basidiomycetesDegradation of dioxins was examined by using the lignin-degrading basidiomycete MZ-340 and its crude enzyme preparation. The enzyme preparation was found to decrease the concentration of dioxins substituted with 2 to 8 chlorines. This phenomenon is thought to be caused by the trapping effect of some protein produced in the culture of this fungus.Thirty-five % of dioxin, which was extracted from the contaminated soil by toluene and adsorbed to glass-beads, was degraded by this fungus. By using silica gel column as an adsorbent, 80 % decrease of adsorbed dioxin as observed. Acid treatment of the polluted soil enhanced the degradation of dioxin by the fungus. Long-term experiment using solid phase culture gave 35 % decrease of added dioxin in 360 days culture at room temperature. Thus, a simple treatment of polluted soil by blending with white-rot fungi is available to the bioremediation of the polluted environment.