Amelioration of the ability to decolorize dyes by laccase: relationship between redox mediators and laccase isoenzymes in Trametes versicolor

摘要

The effect of redox mediators in the dye decolorization by two laccase isoenzymes from Trametes versicolor cultures supplemented with barley bran has been investigated. All the redox mediators tested, 1-hydroxybenzotriazole (HBT), promazine (PZ), para-hydroxybenzoic acid (pHBA) and 1-nitroso-2-naphthol-3,6-disulfonic acid (NNDS), led to higher dye decolorization than those obtained without mediator addition. Among the different tested mediators, PZ was the most effective one at a low range of concentration (0.5–50 μM) and the natural mediator employed, pHBA did not improve significantly the degree of decolorization, and was slightly inhibitory. The two laccase isoenzymes, LacI and LacII, showed different decolorization capability depending on themediator used. No significant differences were detected for NNDS, however LacII was more effective than LacI in the presence of PZ, while in the presence of HBT LacI was the fastest and the most effective isoenzyme.