RESUMO
It has been widely reported that the white rot basidiomycete Phanerochaete chrysosporium, unlike most other white rot fungi, does not produce laccase, an enzyme implicated in lignin biodegradation. Our results showed that P. chrysosporium BKM-F1767 produces extracellular laccase in a defined culture medium containing cellulose (10 g/liter) and either 2.4 or 24 mM ammonium tartrate. Laccase activity was demonstrated in the concentrated extracellular culture fluids of this organism as determined by a laccase plate assay as well as a spectrophotometric assay with ABTS [2,2(prm1)-azinobis(3-ethylbenzathiazoline-6-sulfonic acid)] as the substrate. Laccase activity was observed even after addition of excess catalase to the extracellular culture fluid to destroy the endogenously produced hydrogen peroxide, indicating that the observed activity is not due to a peroxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by activity staining with ABTS revealed the presence of a laccase band with an estimated M(infr) of 46,500.
