Phenol degradation and colour removal in submerged culture of<i>Pleurotus sajor-caju</i>with paper mill effluents

Abstract

The fungus Pleurotus sajor-caju secretes phenol-oxidases that enable the use of recalcitrant compounds as substrates. The residues of paper manufacture contain high lignin levels, which gives the effluents a characteristic brownish colour. To test the potential of P. sajor-caju cultures on reducing these parameters, we used 90% of raw effluents from medium consistency oxygen delignification and bleaching stages plus 10% of mineral solution and different levels of glucose (5–15 g L−1) as substrate. We observed a greater fungal biomass in cultures using effluent than in controls. Cultures containing 10 to 15 g L−1 of glucose resulted in about 42% colour reduction. The polyphenol content was also reduced by 58.9% by the 13th day of culture. In addition, we observed the secretion of laccases (211.44 U mL−1 and 45.98 U mL−1 using ABTS and syringaldazine, respectively) and peroxidases (6.11 U mL−1-ABTS) both peaking at the 7th day of culture and with similar kinetics of production in different glucose concentrations.