[Immobilization of crude laccase onto anion exchange resin and its application in decoloration of malachite green].

Crude laccase from Trametes versicolor was immobilized onto anion exchange resin D201 by three methods, i.e., direct electrostatic adsorption (D201-Lac-I), crosslinking after electrostatic adsorption (D201-Lac-II) and electrostatic adsorption after treating D201 with glutaraldehyde (D201-Lac-III). Compared to direct electrostatic adsorption, the immobilized laccase amount of D201-Lac-II increased by 4.65 times but the laccase activity was decreased to 4.8%, while the laccase activity on D201-Lac-III increased by 2.99 times, with the immobilization amount decreased to 51%. Shadows of laccase aggregation on D201-Lac-III were found by transmission electron microscopy (TEM). Continuous batch decoloration of malachite green demonstrated that the decoloration efficiency of D201-Lac-III remained in the range of 40% to 55% for more than 210 hours, in addition, the enzyme activity on D201-Lac-III maintained unchanged while the activity of free laccase declined to less than 20% under the same condition. All of the results above indicated that D201-Lac-III had a significantly enhanced stability and good reusability. Considering the low price and simple production procedure of crude laccase, D201-Lac-III could be promising for water treatment purpose.