Effect of nutrient nitrogen on laccase production, its isozyme pattern and effluent decolorization by a fungus (NIOCC #2a) isolated from mangrove wood

Carbon and nitrogen sources in the growth medium play an important role in the production of lignin-degrading enzymes in the white-rot basidiomyceteous fungi. The role of nutrient nitrogen sources in growth media on production of lignin-degrading enzymes namely laccase, lignin peroxidase and manganese peroxidase as well as on the decolorization of industrial effluents like black liquor, molasses spent wash and textile mill effluents was studied using the basidiomycetous fungus NIOCC #2a isolated from mangrove wood. The results indicated that the type of nitrogen source used, not only influences the amount and type of lignin-degrading enzymes produced but also has an effect on the decolorization of these effluents. The amount of extracellular peroxidases increased by several fold in the presence of effluents whereas in their absence they were of negligible quantity. Some of the effluents had an inhibitory effect on laccase production. The effect of nitrogen sources in the absence as well as presence of the effluents, on the expression of laccase isoenzymes was studied by non-denaturing SDS-PAGE. It was noticed that a few new isozymes of laccase were induced in the presence of industrial effluents. Decolorization of these effluents by the concentrated culture filtrate obtained from media containing different nitrogen sources further proved the importance of the type of nitrogen source in decolorization of colored industrial effluents.