In vitro treatment of dioxins by enzymes from white-rot fungus.

通过与白腐真菌Ceriporia sp.菌株MZ-340的培养液一起孵育，观察到2，7-二氯二苯并-p-二恶英（diCDD）-回收率的降低。在180分钟内，回收率下降到50 μ M的40%。煮沸对照品中双CDD的回收率高于90%。未回收的diCDD残留在水层中，通过酸、碱或表面活性剂处理反应混合物可回收。这种双CDD捕获活性通过蛋白酶处理和加热而丧失。我们表征了来自真菌的胞外蛋白溶液（EPs）的双CDD捕获活性。在pH 2.7时获得活性的最适pH。在25-45℃范围内观察到超过80%的最大活性。随着培养温度的升高，这种活性急剧下降。在有机溶剂浓度的影响下，分别加入5.0%丙酮和12.5% N，N-二甲基甲酰胺，酶活力消失。对于二苯并呋喃（DF）、联苯（BP）、二苯并噻吩、咔唑、芴、二苯醚和菲，观察到较少或没有捕获活性。以底物的疏水性为指标，对triCDD、diCDF、diCBP和蒽的捕获率均在50%以上，而对DD、monoCDD和tetraCDD的捕获率均低于40%，说明捕集活性的特异性取决于底物的疏水性，而且浓缩的EPs甚至可以捕集octagCDD。

The decrease of 2,7-dichlorodibenzo-p-dioxin (diCDD)-recovery was observed by the incubation with the culture fluid from white-rot fungus Ceriporia sp.strain MZ-340. The decrease of recovery reached 40% of 50uM during 180min period. The recovery of diCDD in the boiled control was higher than 90%. Not recovered diCDD was remained in the water layer, and it was retrievable by treating reaction mixture by acid, alkali or surfactant. Such diCDD-trapping activity was lost by a protease treatment and heating.We characterized the diCDD-trapping activity of the extracellular protein solution (EPs) from the fungus. The pH optimum of the activity was obtained at pH 2.7. More than 80% of the maximal activity was observed within a range of 25-45℃. This activity decreased dramatically as the incubation temperature increased. In the effects of organic solvent concentrations, the activity was disappeared by the addition of 5.0% of acetone or 12.5% of N,N-dimethylformamide, respectively.The substrate specificity was examined on the trapping-activity. Less or no trapping activity was observed for dibenzofuran (DF), biphenyl (BP), dibenzothiophene, carbazole, fluorene, diphenyl ether and phenanthrene. The trapping-activity for triCDD, diCDF, diCBP and anthracene showed over 50%, and that for DD, monoCDD and tetraCDD were lower than 40%, when their rates were expressed as percentages of the activity for diCDD.These results showed that the specificity of the trapping activity depends on the hydrophobicity of the substrate.Furthermore, the concentrated EPs could trap even octaCDD.