DECOLORIZATION OF INDIGO CARMINE BY THE IMMOBILIZED SPORE LACCASE SYSTEMS

Background and Aim:It is estimated that approximately 7 × 105 -1 × 108 tons dyes were produce annually and one-tenth of these dyestuff penetrate the environment through industrial wastes. Dyes have several health and environmental hazards. While physical and chemical methods do not have much success due to their high cost and production of secondary toxic waste, biodegradation of dyes by laccase enzyme is a promising method. The advantages of immobilized systems like improved stability and the reusability of biomolecules, encourage their applications in the bioremediation process.Methods:The spore laccase were obtained from Bacillus strain and entrapped in the three type beads including: alginate-Ca, alginate-Cu, and alginate-Zn. Decolorization processes were performed in the mixture containing of acetate-sodium buffer (0.1 M), dye (25 mg/L), ABTS (0.1 mM), and 30 beads. All mixtures were incubated mildly shaking (150 rpm) at 30 °C. Decolorization rate was determined spectrophotometrically by the relative decrease in absorbance at λmax (610 nm) of dye.Results:The first round complete decolorization was achieved after 150, 300 and 1440 min for the Zn, Cu and Ca beads, respectively. Regarding to reusing the immobilized systems, Zn and Cu beads showed two and twelve decolorization cycles stability. Interestingly for the immobilized system based on alginate-Ca the colorization were proceeded at the higher speed than the first round. The complete decolorizations were observed after 1080, 600, 300, 300, and 240 min for the second, third, fourth, fifth, sixth rounds of reused beads.Conclusion:The results showed the potentials of immobilized laccase systems for bioremediation process.

کلیدواژه ها:

Laccase ، Dye decolorization ، Indigo carmine ، Immobilization