Production of Enzymes and Biotransformation of Orange Waste by Oyster Mushroom, <i>Pleurotus pulmonarius</i> (Fr.) Quél.

Abstract

The wood-decay fungi are able to bioconvert a wide variety of lignocellulosic residues due to the secretion of extracellular enzymes. The use of agricultural wastes as substrate for mushroom cultivation or enzymes production can help to solve environmental problems caused by inadequate discharge in the nature. The production of hydrolytic and oxidative enzymes by Pleurotus pulmonarius developed in solid state system using orange waste as substrate was evaluated in this work. Among the hydrolytic enzymes, pectinase was the main enzyme produced by the fungus, presenting the highest enzymatic activity of 9.4 U/mL after 35 days of cultivation. Considering the oxidative enzymes, laccase was the main enzyme produced with maximal activity of 12.2 U/mL obtained after 20 days of cultivation. Low enzyme levels of manganese peroxidase, β -glucosidase and β -xy-losidase were detected with activity peaks at the end of the cultivation. The enzymatic levels of amylase, carboxymethyl cellulase and xylanase were similar and less than 1.5 U/mL. No aryl-alcohol oxidase activity was detected. NDF, ADF and cellulose values increased during 45 days of cultivation. There was no lignin degradation during the study period and the fungus culture in orange solid waste caused protein enrichment in the substrate. Our results demonstrate that P. pulmonarius was an efficient producer of two important industrial enzymes, pectinase and laccase in a cheap solid state system using orange waste as substrate.