Lignin peroxidase-based cross-linked enzyme aggregates (LiP-CLEAs) as robust biocatalytic materials for sustainable mitigation of textile dyes-contaminated aqueous solution

Abstract Lignin peroxidase (LiP) produced by various basidiomycetous fungi displays a high potential in various biotechnological applications. Extracellular LiP from Schizophyllum commune IBL-06 LiP was insolubilized in the form of CLEAs as a sequential step of protein precipitation, followed by glutaraldehyde cross-linking. The highest relative activity of LiP-immobilized cross-linked enzyme aggregates (LiP-CLEAs) was achieved at 80% saturation with ammonium sulfate and glutaraldehyde concentration of 2.5% (v/v). The optimum pH for the free enzyme was 3.0, whereas the immobilization process caused a slight shift in the pH optima to 4.0. After CLEA formation, the temperature optimum of soluble LiP (35 °C) was favorably increased to 60 °C. Though LiP-CLEAs exhibited a reduced affinity towards its substrate, V max values were increased to 951.9 U/mL compared to 845.1 U/mL by the free enzyme. LiP-CLEAs efficiently catalyzed the biodegradation of representative reactive dyes with 89.6% degradation of Sandal-fix Black CKF dye following 81.46% and 79.6% of Sandal-fix Turq Blue GWF and Sandal-fix Red C4BLN, respectively, after 6 h of treatment. The degradation percentage achieved in the case of LiP-CLEAs was 33.91%, 53.35%, and 25.24% higher than the free form of LiP, respectively. Interestingly, LiP-CLEAs retained 62.3, 64.8, and 68.6% residual activities for the degradation of S.F. Red, S.F. Black, and S.F. Turq Blue, respectively, after three repeated cycles. Overall, the results suggest that the LiP-CLEAs might have a robust biotechnological potential to mitigate a wide range of dyes and emerging contaminants.