Thirty wood-inhabiting basidiomycetes were screened for their ability to selectively delignify wood, The amount of lignin and carbohydrates removed and the mo hological and ultrastructural characteristics of the decayed wood were the major criteria used to determine fungi with superior lignin-degrading ability. Phellinus pini-2, Pholiota mutabilis, Phlebia brevispora-l and Phanerochaete chrysosporium were the best delignifiers of both birch and pine. Different isolates of the same species of fungi differed in both the type of decay caused and their selectivity for lignin. Almost all fungi tested caused greater weight losses in birch blocks than in pine blocks. Most fungi isolated from gymnosperms caused greater weight losses in pine than did isolates from angiosperms. The fungi studied produced two different types ofselective delignification. The first type resulted in extensive lignin removal from localized areas within wood blocks. The second type resulted in a more uniform loss throughout wood blocks, but less extensive loss from individual cell walls.

The phenol oxidases from mature fruiting bodies of Lentinus edodes (Berk.) Sing., a commercially cultivated mushroom, were studied. The major phenol oxidase was a laccase with a pH optimum near 4.0 and an apparent molecular weight of 100000. Catechol oxidase and tyrosinase were also present. The laccase investigated was primarily extracellular ; the highest activity was in the pigmented rind of the pileus and in the stipe. Increased laccase activity was associated with rapid growth of non-pigmented aerial mycelium and formation of pigmented primordia and fruiting bodies. Possible functions of the laccase and its regulation during the development of fruiting bodies are discussed.

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Extracellular culture filtrates from ligninolytic cultures of the lignin-degrading basidiomycete Lentinula (syn. Lentinus) edodes (Berk.) Pegler contained one major peroxidase when grown on a commercial oak-wood substrate. The peroxidase was purified by polyethylenimine clarification, anion-exchange chromatography, and hydrophobic-interaction HPLC. The enzyme (MnP1) was a heme-iron protein with an apparent molecular weight of 44,600 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and an isoelectric point of pH 3.2. The native enzyme had an absorption maximum at 407 nm, which shifted to 420 nm upon H2O2 addition. The pyridine-hemochrome-absorption spectrum indicated that one heme group was present per enzyme as protoporphyrin IX. N-Terminal amino acid sequencing showed that MnP1 had higher sequence homology with manganese peroxidases than with lignin peroxidases reported from Phanerochaete chrysosporium. L. edodes MnP1 was capable of oxidizing lignin and lignin-model compounds in the presence of manganese and H2O2.