Removal of synthetic dyes by an eco-friendly strategy

In this paper an eco-friendly strategy for the removal of synthetic dyes from aqueous Solutions was proposed. Thus, in a first step the dyes were adsorbed onto sunflower seed shells (SS) by using a batch technique. Subsequently, in a second step, these dyed SS were used as support-substrates to produce laccase by the white-rot fungus Trametes pubescens under semi-solid-state conditions. The effect of inducer addition on laccase production was studied. The optimum conditions (addition of both 0.5 mM Cu+2 and 50 mu M tannic acid on the 3(rd) day of cultivation) led to a maximum laccase activity of 30272 U/L. Further, the system was efficiently scaled-up to laboratory bioreactors producing a maximum activity of 40172U/L together with a total decolouration of the adsorbed dye. In addition, SDS-PAGE showed that laccases were the only enzymes present in the extracellular fluid. Therefore, apart front dye removal this approach allowed the production Of high titres of laccase, Which was obtained almost pure (only needed to be ultra-filtrated).