Increasing ligninolytic enzyme activities in several white-rot Basidiomycetes by nitrogen-sufficient media

Ligninolytic enzyme activities were monitored in five white-rot fungi cultivated on nitrogen (N)-limited glucose-BIII medium and were compared with the activities obtained in media supplemented with 56 mm peptone-N. Only Phanerochaete chrysosporium and two Bjerkandera strains produced detectable lignin peroxidase (LiP) activity. LiP was stimulated by either N-limitation or N-sufficiency in P. chrysosporium and Bjerkandera spp., respectively. All of the fungal strains tested produced manganese-dependent peroxidase (MnP) activity, which was consistently stimulated by the peptone supplementation. Both the manganese-independent peroxidase (MiP) activities, which were detected only in Bjerkandera spp., and the laccase activities, which were detected only in Lentinula edodes and Pleurotus ostreatus, were also enhanced by peptone. In several fungal strains, the activity of ligninolytic enzymes was likewise stimulated by supplying 56 mm NH⁺₄-N at an initial pH of 7·3. This study indicates that several commercially important and commonly occurring white-rot fungi produce higher ligninolytic enzyme activities in response to a nitrogen-rich medium, in contrast to the physiological model proposed for P. chrysosporium.