Appraisal of malachite green biodegradation and detoxification potential of laccase from Trametes cubensis

Abstract

The laccase from the newly isolated Trametes cubensis was investigated for its potential to degrade malachite green (MG) dye. Optimized solid-substrate fermentation enhanced laccase production by 8.8-fold, reaching an activity of 6577.0 ± 14.3 U/g. Proteomic characterization identified enzyme with 4 % sequence coverage, molecular weight of 43.1 kDa, and alignment with multicopper oxidases. Using one-factor-at-a-time optimiza tion, MG decolorization was maximized at 89 % under optimal conditions: 20 U/mL enzyme dose, 0.1 mg/mL dye concentration, pH 5.0, and 2 h incubation at 50 ◦ C. Crosslinking the laccase onto chitosan beads resulted in 82 % immobilization efficiency, with high recyclability and reusability, retaining over 52 % activity after 7 cycles and demonstrating similar (p < 0.05) dye degradation potential. MG degradation products exhibited significantly reduced phyto-, cyto-, and microbial toxicity. The degradation pathway was elucidated using gas chromatography-mass spectrometry analysis. Thus, both free and immobilized laccase from T. cubensis offer sustainable tool for effective MG degradation with reduced toxicity.