SCREENING OF 68 SPECIES OF BASIDIOMYCETES FOR ENZYMES INVOLVED IN LIGNIN DEGRADATION

A survey for enzymes involved in lignin degradation was carried out from 90 strains of 68 species of different groups of basidiomycetes. Laccase activity was found in 50% of the fungi tested, whereas aryl-alcohol oxidase (AAO) and Mn-dependent peroxidase (MnP) were detected in 40% and 29% of species, respectively Laccase activity of more than 200 U l(-1) was obtained in cultures of Trametes versicolor, Phellinus torulosus, Cerrena, unicolor and Pleurotus eryngii, whereas the AAO and MnP levels were comparatively lower, and lignin peroxidase was not detected in the different fungi tested. Previously known AAO-producing fungi, P. eryngii and Bjerkandera adusta, showed the highest AAO activities, and the enzyme was detected for the first time in fungi from very different taxonomic groups, including the gasteromycete Cyathus olla. In contrast to laccase and AAO, MnP seemed to be restricted to species of Aphyllophorales, with the exception of the tremellaceous fungus Exidia glandulosa. It is interesting to note that MnP was found in most Phellinus species, P. ribis, P. trivialis and P. torulosus producing the highest activities among the fungi studied. Simultaneous production of MnP and H2O2-producing AAO was found in several polyporaceous fungi, but the latter enzyme was absent from the above Phellinus species.