The ligninolytic enzymes lignin peroxidase (LIP) and manganese dependent peroxidase (MnP), were detected in extracellular fluids of Phanerochaete flavido-alba! FLP 106507 cultures under carbon or nitrogen limitation. MnP activities were found to be higher than LiP activities under all growth conditions tested. Higher titres of both peroxidases were obtained under carbon limitation in excess nitrogen. Isoelectric points (pIs) observed after FPLC and IEF of concentrated extracellular fluids revealed more acidic pIs for LIP enzymes obtained in nitrogen-limited cultures than those in carbon-limited cultures. However, the change in the limiting growth factor does not significantly affect MnP pIs.