Decolorization of Remazol Brilliant Blue R by White-rot Fungus Trametes hirsuta AK04 Immobilized on Lignocellulosic Oil Palm Fibers

Abstract

Water contamination by Remazol Brilliant Blue R (RBBR) can cause harmful effects on aquatic organisms due to its toxicity and recalcitrance in the environment. This study aimed to employ the oil palm fibers (OPFs)-immobilized white-rot fungus Trametes hirsuta AK04 to decolorize this dye and assess the alternative utilization of fungal-treated OPFs wastes. The fungus was able to utilize RBBR as a sole carbon and energy source. However, the decolorization efficiency was markedly enhanced by the supplementation of glucose as co-substrates. Veratyl alcohol (VA) was the best inducer to enhance the activities of laccase and manganese peroxidase associated with the decolorizing activity. The addition of 0.1 mM of VA along with glucose could accelerate the initial decolorization rate by the immobilized fungus, reaching 97% dye removal in 12 h. Fourier-transform infrared spectroscopy detected changes in the functional groups of dye and the formation of the degradation products, as well as changes within lignin and hemicellulose molecules in OPFs after decolorization. Sequentially, the fungal pretreatment of OPFs for 7–14 days resulted in increased lignin degradation and cellulose content, suggesting the possible use of treated OPFs as substrates for the further production of biofuels and other valuable products.