Lignin-modifying enzymes of Flavodon flavus, a basidiomycete isolated froma coastal marine environment

A basidiomycetous fungus Flavodon flavus (Klotzsch) Ryvarden (strain 312), isolated from decaying sea grass from a coral lagoon off the west coast of India, mineralized nearly 24% of C-14-labeled synthetic lignin to (CO2)-C-1 4 in 24 days. When grown in low-nitrogen medium (2.4 mM N) this fungus prod uced three major classes of extracellular lignin-modifying enzymes (LMEs): manganese-dependent peroxidase (MNP), lignin peroxidase (LIP), and laccase. Low MNP and laccase activities were seen in high-nitrogen medium (24 mM N) , but no LIP activity was seen. In media containing lignocellulosic substra tes such as pine, poplar, or sugarcane bagasse as the sole source of carbon and nitrogen, relatively high MNP and moderate levels of laccases were see n, but LIP production either was not seen or was minimal, LME production wa s also seen in media prepared with artificial seawater. Fast protein liquid chromatography and isoelectric focusing resolved LMEs into four isozymes e ach of MNP and LIP, while laccase isozymes were resolved into two groups, o ne group containing seven isozymes (pIs 4 to 6) and the other group contain ing at least three isozymes (pIs < 3), The molecular masses of the differen t isozymes were 43 to 99 kDa for MNP, 40 and 41.5 kDa for LIP, and 43 and 9 9 kDa for laccase. F. flavus showed effective degradation of various dye po llutants in media prepared with or without artificial seawater. This is the first report on the production of all three major classes of LMEs by F. fl avus and points to the bioremediation potential of this organism in terrest rial as well as marine environments.