Decolorization of two synthetic dyes using the purified laccase of Paraconiothyrium variabile immobilized on porous silica beads

Background: decolorization of hazardous synthetic dyes using laccases in both free and immobilized form hasgained attention during the last decades. the present study was designed to prepare immobilized laccase (purifiedfrom paraconiothyrium variabile) on porous silica beads followed by evaluation of both free and immobilizedlaccases for decolorization of two synthetic dyes of acid blue 25 and acid orange 7. effects of laccaseconcentration, ph and temperature alteration, and presence of 1-hydroxybenzotriazole (hbt) as laccase mediatoron decolorization pattern were also studied. in addition, the kinetic parameters (km and vmax) of the free andimmobilized laccases for each synthetic dye were calculated.results: immobilized laccase represented higher temperature and ph stability compare to free one. 39% and 35%of acid blue 25 and acid orange 7 was decolorized, respectively after 65 min incubation in presence of the freelaccase. in the case of immobilized laccase decolorization percent was found to be 76% and 64% for acid blue 25and acid orange 7, respectively at the same time. increasing of laccase activity enhanced decolorization percentusing free and immobilized laccases. relative decolorization of both applied dyes was increased after treatment bylaccase-hbt system. after nine cycles of decolorization by immobilized laccase, 26% and 31% of relative activitywere lost in the case of acid blue 25 and acid orange 7, respectively.conclusions: to sum up, the present investigation introduced the immobilized laccase of p. variabile on porousbeads as an efficient biocatalyst for decolorization of synthetic dyes.