| Summary: | <i>Trametes hirsuta</i> is able to secrete laccase isoenzymes including constitutive and inducible forms, and has potential application for bioremediation of environmental pollutants. Here, an inducible group B laccase from <i>T. hirsuta</i> MX2 was heterologously expressed in <i>Pichia pastoris</i>, and its yield reached 2.59 U/mL after 5 days of methanol inducing culture. The optimal pH and temperature of recombinant laccase (rLac1) to 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were 2.5 and 60 °C, respectively. Metal ions showed different effect on rLac1 which Mg<sup>2+</sup>, Cu<sup>2+</sup>, and K<sup>+</sup> increased enzyme activity as their concentration increased, whereas Zn<sup>2+</sup>, Na<sup>+</sup>, and Fe<sup>2+</sup> inhibited enzyme activity as their concentration increased. rLac1 showed good tolerance to organic solvents, and more than 42% of its initial activity remained in 10% organic solvents. Additionally, rLac1 exhibited a more efficient decolorization ability for remazol brilliant blue R (RBBR) than for acid red 1 (AR1), crystal violet (CV), and neutral red (NR). Molecular docking results showed RBBR has a stronger binding affinity with laccase than other dyes by interacting with substrate binding cavity of enzyme. The results indicated rLac1 may be a potential candidate for dye removal from textile wastewater.
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