Degradation of juglone by Pleurotus sajor-caju

Pyrene and Chrysene Tolerance and Biodegradation Capability of Pleurotus Sajor-Caju

Introduction:

The present work focused on the biodegradation capability of a white-rot fungus, the Pleurotus sajor-caju, when exposed to polycyclic aromatic hydrocarbons.

Methods:

The research was carried out by using in vitro systems developed on Petri dishes, to evaluate the fungal tolerance to pyrene and chrysene, followed by experiments in liquid medium. The first experimental campaign was necessary to evaluate the conditions promoting fungal growth and tolerance (presence of surfactants, peptone, copper sulphate and lecithin) and it was designed and analysed using statistical techniques.

Results:

It was found that the fungal population growth is strongly inhibited by chrysene presence. On the other hand, pyrene had a mild negative impact on the mycelia growth, which seemed to be positively influenced by the presence of Tween 80 and copper sulphate. Starting from these results, the behaviour of Pleurotus sajor-caju in presence of pyrene was investigated in liquid medium. Results showed that the depletion of pyrene was evident during a period of 20 days, and removal efficiency was greater than 90%.

Fungal laccases as tools for biodegradation of industrial dyes

Laccases are blue copper oxidases, found in some plants and secreted by a wide range of ligninolytic fungi. These enzymes are well known for their ability in oxidizing several organic compounds, mainly phenolics and aromatic amines, at the expenses of molecular oxygen. Therefore, they could find application in the field of enzymatic bioremediation of many industrial wastewaters, and in particular to bleach and/or detoxify dye-containing effluents. Not all industrial dyes behave as laccase substrates, but this limitation is often overcome by the judicious use of redox mediators. These could substantially widen the application range of laccases as bioremediation tools. The present study encompasses the main properties of the most used industrial dyes as related to their chemical classification, fungal laccases and their molecular and catalytic features, the use of redox mediators, limitations and perspectives of the use of fungal laccases for industrial dye bleaching.