CONICET | Buscador de Institutos y Recursos Humanos

In the present work, we investigated the use of solid residues from P. ostreatus mushroom production to adsorb and decolorize different dyes. The solid residue used in this study was composed of hemicellulose and cellulose (52.81%), acid-insoluble lignin (25.42%), chitin (6.5%) and water extractives (14.82%). Laccase and manganese peroxidase (MnP) activities, after 4 h of 14% (wt/vol) solid residue incubation in distilled water, were 0.5 U g-1 and 12 mU g-1 respectively. Enzymatic decolorization percentages were up to 100 for azure B (heterocyclic dye) and indigo carmine (indigoid dye), 74.5 for malachite green (MG) (triphenylmethane dye), and zero for xylidine (azoic dye). Optimum decolorization temperature was in the 26-36ºC range for all dyes. Data obtained on adsorption (enzymatic decolorization was prevented with sodium azide) at different dye concentrations and in a pH range of pH 3 to 7 were used to plot Freundlich isotherms. The SFS displayed large differences in the adsorption capacity depending of the different dyes tested. The highest adsorption capacity was observed at pH 3 for MG, while xylidine was slightly adsorbed at pH 3 and 4 but not adsorbed at higher pH values. Laccase and MnP production showed to be affected by the presence of the dyes. Highest enzyme levels were observed in the presence of MG where laccase and MnP increased 1.39- and 2.13-fold, respectively. Decolorization and adsorption to SFS are both important processes in removing dyes from aqueous solutions. The application of this spent substrate for dye wastewater treatment will be able to take advantage of both of these dye removal processes. An important problem in bioremediation processes involving microorganisms is the requirement of a time period for their growth, results of this report demonstrated that the use of spent substrates from mushroom cultivation solve such problem.