The application of laccase-rich extract of spent mushroom substrates for removing lignin from jute fabric waste: a dual management approach

Spent mushroom substrate (SMS) represents a growing waste from the mushroom cultivation sector due to increased popularity worldwide. SMS is rich in lignocellulolytic enzymes, allowing it to be recycled. Further, these enzymes can be applied to the sustainable use of natural fibers like jute, which need lengthy and expensive chemical processing methods. The study explored the dual sustainable management of two waste materials, SMS and jute fabric. SMS was examined as a source of lignin-degrading enzyme laccase to delignify jute and allow it to be processed sustainably. Response surface methodology (RSM) was applied to simultaneously optimize the extraction of laccase from various mushroom species SMS. Temperature, time of extraction, and pH were the independent variables evaluated in RSM. The most active enzyme was laccase from Pleurotus ostreatus SMS (P-SMS). RMS-based optimization of extraction enabled 1.47-fold increase in laccase activity. P-SMS laccase was partially purified, and its activity's optimal conditions (pH and temperature) were assessed. Jute fabric was treated with the extracted laccase under mild conditions (40˚C and pH 4.5), enabling the removal of 61.1% of the lignin, providing a softer and lighter appearance with an improvement in the wetting time confirmed by ATR-FTIR and polarized light microscopy. This work demonstrated the applicability of SMS-derived laccase extraction, using mild conditions to delignify jute fabric waste in an environmentally friendly way, thus creating a sustainable chain of waste processing steps.