Removal of dyes by Trametes versicolor laccase immobilized on NaY-zeolite.

In the present study, the immobilization of Trametes versicolor laccase (Tv Lac) was optimized on the synthesized NaY-zeolite by experimental of design. For this purpose, the central composite design was employed to study the effects of the immobilization parameters on the activity of the immobilized Tv Lac on the NaY-zeolite. The optimum conditions were occurred at 2.5 mg/mL of NaY-zeolite concentration, 1 U/mg of enzyme concentration, 1 mM of glutaraldehyde concentration for 4 h immobilization time at 4 °C. In these conditions, the laccase activity developed to 15.68 ± 0.56 U/mg, which was very close to the predicted amount (16.09 ± 1.6 U/mg). Generally, the immobilized Tv Lac showed stability higher than that of the free Tv Lac at the different temperatures and pHs. The activity of the immobilized Tv Lac on the NaY-zeolite was 88.2% and 98.3% after incubation for 120 min at 60 °C and pH 5, respectively. Moreover, the free Tv Lac and immobilized Tv Lac on NaY-zeolite retained about 54.2% and 78.3% of its initial activity after 15 days of storage. The immobilized Tv Lac lost near 20% of its initial activity after 5 cycles of uses. The immobilized Tv Lac exhibited higher efficiency (93.0 ± 1.7% and 80.3 ± 1.8%, respectively) in removal of bromothymol blue (BTB) and trypan blue compared with the free Tv Lac (23.7 ± 1.8% and 15.1 ± 1.5%, respectively). Meanwhile, the kinetic parameters (K m and V max) for immobilized Tv Lac were 0.07 µM and 1.38 µmol/min, respectively, for removal of BTB. Therefore, the immobilized Tv Lac as a good candidate could be suggested for the elimination of dye-containing pollutants due to its high efficiency (more than 80%), which requires further investigations. [Display omitted] • The NaY-zeolite was used for immobilization of Trametes versicolor laccase (Tv Lac). • Central composite design was employed to optimize the immobilization conditions. • Tv Lac was successfully immobilized on NaY-zeolite by IY of 97.22% and IE of 101.04%. • Stabilities and reusability of the immobilized laccase were significantly improved. • The immobilized Tv Lac exhibited high efficiency in removal of BTB. [ABSTRACT FROM AUTHOR]