Characterization and application potential of a robust recombinant laccase rtplcc3 from trametes polyzona for textile dye decolorization

Abstract

Abstract Laccases (EC 1.10.3.2) are promising biocatalysts for textile wastewater treatment. Here, we identified a novel laccase, TpLcc3, from Trametes polyzona MUCL 38443, heterologously expressed it in Pichia pastoris , and evaluated its biochemical properties and dye-removal performance in citrate buffer (CB) and simulated industrial dyebath effluent (DB). The glycosylated recombinant enzyme (rTpLcc3) exhibited maximal activity at 70°C and pH 3.0, broad pH tolerance (pH 4.0–8.0 at 25–30°C), and substantial thermal stability with half-lives of 187 min at 50°C and 19 min at 70°C. rTpLcc3 showed high catalytic efficiency toward ABTS (k cat /K m = 576.76 µM⁻¹ s⁻¹), placing it among high-performing fungal laccases. rTpLcc3-alone effectively decolorized azo dyes-Acid Black 194 (AB194) and Bismarck Brown, with AB194 showing the highest removal in CB (71.39 ± 6.16%) and DB (42.17 ± 5.69%). Mediator supplementation markedly enhanced decolorization, with ABTS enabling rapid, complete removal of AB194, and 90% removal of Malachite Green in both matrices. Across dye classes, ABTS and syringaldehyde were the most effective mediators in CB (72.4 ± 21.8% and 71.4 ± 28.3% mean decolorization, respectively), while ABTS remained superior in DB (80.1 ± 27.8%). Notably, the TpLcc3/mediator systems completely detoxified the toxic dyes Malachite Green, and Crystal Violet while removing the remaining dyes without evidence of harmful end-product formation.