Characterization of thermostable β-glucosidase immobilized on linen fabric

In this study, a thermostable β-glucosidase derived from a hot spring metagenome was successfully immobilized on linen fabric to create an eco-friendly and reusable biocatalyst for lactose hydrolysis. The enzyme is derived from a metagenome of the high-temperature Pisciarelli hot springs, an extreme environment known to yield robust biocatalysts with industrial relevance. Two immobilization strategies were employed: direct covalent binding (Lf-β-glucosidase) and binding via a spacer arm (LfEG-β-glucosidase). The latter exhibited superior enzymatic performance, retaining 76.6% of its initial activity and demonstrating enhanced thermal and operational stability. Both free and immobilized forms of enzyme showed similar pH and temperature optima, with the immobilized form exhibiting significantly improved long-term thermostability and storage stability, retaining full activity after 1 yr at 4°C. The LfEG-β-glucosidase biocatalyst was effectively applied in the enzymatic treatment of cheese whey, retaining 90% activity after 15 reuse cycles, yielding more than 6.4 g of glucose. These findings highlight the promising use of biodegradable, low-cost linen fabric as a carrier for thermostable enzymes in food biotechnology. The high efficiency and reusability of the developed biocatalyst offer a compelling solution for lactose hydrolysis and valorization of dairy industry by-products, particularly whey, within a circular and environmentally conscious production model.