The effect of violuric acid on the decolourization of recalcitrant dyes by laccase from Trametes hirsuta

In this paper, the effect of the redox mediator violuric acid (VA) on the decolourization of the two recalcitrant acid dyes C.I. Acid Red 97 and C.I. Acid Green 26 by crude laccase obtained from Trametes hirsuta cultures was investigated. The laccase–mediator system (LMS) led to a higher extent of decolourization in shorter times than that obtained without mediator addition, especially for C.I. Acid Red 97 infact the dye was almost totally decolourized (about 90%) in only 3 min. In addition, the stability of laccase against VA was also assessed.