Biomass pyrolysis-derived aqueous phase as a laccase inducer in Pleurotus ostreatus: laccase production, properties, and applications

The aqueous phase (AP) generated during biomass pyrolysis is often considered a waste product due to its dilute and toxic nature, making it difficult to upgrade. This study explores the potential of using AP as a laccase inducer for the white-rot fungus, Pleorotus ostreatus, and as a mediator in laccase-catalyzed reactions. As an inducer, AP increased laccase production from P. ostreatus to 570 U/g, outperforming copper, a common inducer, by almost 180%. A maximum laccase yield of 955 U/g was achieved when P. ostreatus was co-induced by both AP and copper. Characterization of the AP-induced laccase revealed greater pH tolerance relative of this enzyme compared to copper-induced laccase. The AP-induced laccase was further evaluated for various applications. Laccase alone was effective in decolorizing coomassie blue dye, increasing saccharification yield from prairie biomass, and detoxifying tetracycline. When laccase was mediated with AP, the enzyme was also capable of decolorizing crystal violet dye, demonstrating additional benefit of AP to mediate laccase-based oxidation reactions with certain substrates. Overall, these findings suggest that using AP to induce laccase production, and potentially mediate the laccase-based reactions, could be a promising method to valorize this byproduct from biomass pyrolysis.