Degradation of Synthetic Polymer by White Rot Fungi

研究了不同营养条件下白腐菌Izu-154、黄孢原毛平革菌(Phanerochaete Chrysosporium)和杂色曲霉(Trametes Versicolor)对高分子量聚乙烯膜的降解作用。在氮素或碳素限制培养条件下，IZU-154在三种白腐菌中对聚乙烯的降解作用最显著。此外，对于杂色假单胞菌和黄孢霉，在氮限或碳限培养基中添加Mn(II)促进了聚乙烯的降解。这些结果表明，聚乙烯的降解与白腐菌的木质素分解酶，如锰过氧化物酶(MNP)有关。用部分提纯的MNP处理聚乙烯膜，在吐温80、MnSO4作为Mn(II)和丙二酸缓冲液的存在下，聚乙烯膜的降解显著。然而，外源H_2O_2的加入并不是降解所必需的，尽管人们已经认识到H_2O_2是引发MnP的必要条件。研究了吐温80在MNP降解聚乙烯中的可能作用以及在没有H_2O_2的情况下MNP作用的基础。结果表明，吐温80等表面活性剂对体系中的MNP具有稳定作用。我们还指出，丙二酸与微量的自氧化生成的Mn(III)反应生成的过氧化产物可用于引发MNP。

Degradation of high-molecular-weight polyethylene membrane by white rot fungi, IZU-154, Phanerochaete chrysosporium, and Trametes versicolor, was investigated under various untritional conditions. IZU-154 showed the most significant polyethylene degradation among the three white rot fungi under nitrogen-or carbon-limited culture conditions. Furthermore, for T.versicolor and P.chrysosporium, the addition of Mn (II) into nitrogen- or carbon-limited culture medium enhanced polyethylene degradation. These results suggest that polyethylene degradation is related to ligninolytic enzyme such as manganese peroxidase (MnP) of white rot fungi. Treatment of polyethylene membrane with partially purified MnP caused significant degradation in the presence of Tween 80, MnSO_4 as Mn(II), and malonate buffer. However, the addition of exogenous H_2O_2 was not necessary for the degradation, although it is recognized that H_2O_2 is essential for the initiation of MnP.A possible role of Tween 80 in the polyethylene degradation by MnP and the basis of the MnP action in the absence of H_2O_2 were investigated. The results showed that the surfactants such as Tween 80 can stabilize MnP in the system. We also indicated that the peroxides derived from the decomposition of malonate by a trace amount of Mn(III) which is formed by autoxidation of Mn (II) can be used for the initiation of MnP.