To characterize the degradation of hardwood by brown rot fungus, Coniophora puteana was incubated on the wood blocks of Quercus accutissima. For comparison, the same fungus was also incubated on the pine wood blocks of Pinus densiflora. In softwood, the shape of the wood cells and thickness of the cell appeared unchanged even the loss of birefringence in the affected areas. In contrast, oak wood decayed by brown rot fungus showed the erosion of wood cell walls from lumen towards the middle lamella. Complete degradation of cell walls including the lignin- rich middle lamella occurred in some areas of the oak wood cells. Degradation modes of brown rot fungus C. puteana in oak wood followed a typical white rot. The production of hydrogen peroxide was confirmed cytochemically by the deposition of cerium chloride in the degraded wood cell walls. However, Bavendamm test was negative to C. puteana. The present work suggested that hydrogen peroxide produced by brown rot fungus might be associated with not only the depolymerization of cellulose in softwood but also the degradation of lignin in hardwood.

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