Screening of fungal isolates and properties of Ganoderma applanatum intended for olive mill wastewater decolourization and dephenolization.

AIMS: To investigate different autochthonous isolates of wood-rotting fungi for the removal of both colour and phenolic compounds from olive mill wastewaters (OMW).

METHODS AND RESULTS: The isolates Bjerkandera adusta Ba-100, Fomes fomentarius Ff-106, Ganoderma applanatum Ga-20, Irpex lacteus Il-3, Trametes versicolor Tv-101 and Tv-103 were preliminarily screened for their OMW-decolourizing potential on potato dextrose agar supplemented with different OMW concentrations. A further screening of batch cultures under different agitation speeds, to test the effect of shear stress, resulted in the selection of isolate G. applanatum Ga-20. Batch cultures grown in OMW-based medium exhibited strong laccase induction and significant decrease in the values of phenols, colour and chemical oxygen demand. Concomitant onset of laccase activity and colour removal was observed, and apart from laccase, neither lignin peroxidase nor manganese-dependent peroxidase activities were detected. Moreover, the depletion of aromatic compounds with high and low apparent molecular mass was observed by chromatographic analysis.

CONCLUSIONS: Isolate G. applanatum Ga-20 exhibited interesting properties for its use in bioremediation of OMW, namely high removal of recalcitrant phenolic compounds and strong colour abatement.

SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time, the white-rot fungus G. applanatum proves to be effective for the decolourization and dephenolization of OMW.