Immobilization of Aspergillus sp. laccase on anionic agarose supports and application in a fixed-bed system for phenolic substrate oxidation

Water contamination by emerging pollutants, particularly phenolic compounds, poses a major environmental challenge due to their high stability and persistence in aquatic systems. Enzymatic degradation using laccases has emerged as a promising alternative to conventional removal techniques; however, low stability and reuse capacity of free enzymes limit their industrial application. In this study, laccase from Aspergillus sp. was immobilized onto two anionic agarose-based supports, MANAE-agarose and PEI-agarose, to enhance its catalytic performance and operational stability. Both supports enabled rapid immobilization, with MANAE-agarose exhibiting higher activity recovery. Immobilization increased resistance to pH and temperature variations, promoting a shift in optimal pH and improving overall stability compared with the free enzyme. Fixed-bed column assays demonstrated superior catalytic performance for the Lac-MANAE derivative, which maintained high ABTS oxidation capacity over 11 operational cycles, whereas Lac-PEI showed reduced performance after the first cycle. These findings highlight the potential of low-cost anionic supports, particularly MANAE-agarose, for continuous biocatalytic degradation of phenolic pollutants in water treatment applications.