Degradation of Synthetic Polymer by White Rot Fungi

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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.