Efficient recovery of laccase enzyme from mushroom spent and its application in dye biodegradation in wastewater

Abstract

Environmental pollution caused by synthetic dyes, especially azo dyes, poses significant challenges due to their persistence and toxicity in wastewater. This study aimed to extract and evaluate the laccase enzyme from mushroom spent, an underutilized agricultural waste for its potential in dye biodegradation. Spent substrates from Pleurotus ostreatus (Oyster mushroom) and Agaricus bisporus (Button mushroom) were collected and processed to extract crude laccase enzyme using sodium acetate buffer under cold conditions. Qualitative screening confirmed the presence of laccase activity, and the extracted crude was tested for its efficiency in degrading bromothymol blue and methyl orange dyes. Among the tested samples, the oyster mushroom spent from Gannoruwa yielded the highest amount of crude enzyme (average 4.18 g per 20 g of spent), whereas the button mushroom spent showed significant dye degradation, achieving up to 48.6% decolorization of bromothymol blue. Notably, the oyster mushroom laccase from Gannoruwa showed promising activity against methyl orange (60.13% degradation), but not bromothymol blue. The study also highlighted the importance of parameters such as pH and temperature in maintaining enzymatic activity, with optimal degradation observed at pH 4.5. These findings suggest that mushroom spent is a viable and sustainable source of laccase for eco-friendly dye wastewater treatment. However, future studies should focus on enzyme purification, activity quantification, and testing with a broader range of dyes for industrial application.