No abstract

The ligninolytic enzymes lignin peroxidase (LiP) and manganese dependent peroxidase (MnP), were detected in extracellular fluids of Phanerochaete flavido-alba FPL 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.

Lignin-degrading enzymes were partially purified from supernatant solutions obtained from Phanerochaete flavido-alba-decolorized olive oil mill wastewaters (OMW). The dominant enzymes, manganese peroxidases, exhibited different isoform patterns in decolorized OMW-containing cultures than in residue-free samples. Laccase induction was also detected in OMW-containing cultures but not in control cultures.

Olive oil mill wastewater (OMW), a major waste product of olive oil extraction, contains many recalcitrant compounds, mainly present in the colored fraction. In this study we attempted to identify optimum culture conditions for the decolorization of OMW by Phanerochaete flavido‐alba for subsequent use in bioremediation assays. Of several media tested, nitrogen‐limited P. flavido‐alba cultures containing 40 mg/L Mn(II) were the most efficient at decolorizing OMW. Decolorization was accompanied by a 90% decrease in the OMW phenolic content. Concentrated extracellular fluids alone (showing manganese peroxidase, but not lignin peroxidase activity) did not decolorize the major OMW pigment, suggesting that mycelium binding forms part of the decolorization process.

Manganese supplementation of culture medium affected Phanerochaete flavido-alba FPL 106507 growth, glucose consumption and extracellular protein accumulation. Both the titre and time of detection of lignin peroxidase (LiP) were affected by manganese concentration in the medium, whereas with manganese peroxidase (MnP) only the titre was affected. In high Mn(II) containing cultures highest manganese peroxidase levels and a decrease in extracellular veratryl alcohol accumulation were observed. After FPLC a number of haemprotein peaks showing manganese peroxidase activity were detected in Mn(II) supplemented cultures. On the contrary, only haemprotein peaks of lignin peroxidase were detected in culture medium not supplemented with Mn(II). ß