EVALUATION OF ENTRAPMENT APPROACH FOR SPORE LACCASE IMMOBILIZATION

Background and Aim:Laccase enzymes (1,4-benzenediol: oxygen oxidoreductases, EC 1.10.3.2) are copper-containing proteins that oxidase a variety of aromatic substrates. They possess great potentials for biotechnological and environmental applications. Enzyme immobilization was defined as confining the enzyme molecules to a solid matrix different from the one in which substrate are present. The main aim of immobilization is to obtain stable and reusable enzymes with resistance to different environmental factors.Methods:In the current study we applied entrapment approach to immobilize the spore laccase from Bacillus sp. KC2. Different concentration of sodium alginate (0.1, 0.5, 1.0, 1.5, 2, 2.5, and 3.0 %w/v), calcium chloride (0.1, 0.15, 0.2, 0.25, 0.3 M), zinc sulfate (0.1, 0.15, 0.2, 0.25, 0.3 M) and, copper sulfate (0.025, 0.05, 0.1, 0.15, 0.2 M) were varied to determine the best immobilized system with the activity in different pH and temperatures. Laccase activity was measured colorimetricaly based on the oxidation of ABTS (0.1 mM, at 420 nm).Results:The highest immobilization efficiency were found to be as 89%, 83% and 80% in the beads formed by mixing 2% (w/v) alginate with 0.3, 0.2, and 0.05 M, Zn2+, Ca2+, and Cu2+, respectively. In the optimum pH (4.5 for all beads), and temperatures (35°C for Cu, 50°C for Zn and Ca beads) conditions the enzymes activity of entrapped spore laccase were equal to 10, 3.3 and 2.8 mU/bead in the Zn, Ca, and Cu beads, respectively.Conclusion:The results showed the entrapment approach have great potentials to produce immobilized laccase system with activity in various conditions.

Keywords:

Laccase , Immobilization , Bacillus