Stimulation of laccases from Trametes pubescens: Use in dye decolorization and cotton bleaching

The production of laccases from Trametes pubescens was investigated along with the role of nutrients and elicitors. Copper proved to be a fundamental inducer, although productivity yields were consistently enhanced only in presence of additional compounds (textile dyes). Using a central composite design, the optimal culture condition was examined, by taking into consideration three distinct variables and their combinatorial effect. 290 U/ml of laccases were produced after setting nitrogen, copper and Reactive Blue 19 concentration; in a bioreactor, activity recovery was lower (90 U/ml) and pellet morphology different. The activity of the laccase crude extract was maximal at 60 °C, and stable for 14 h at 50 °C and for 2 months at pH 6 and room temperature. The biotechnological potential was assessed, confirming the capacity to decolorize single or mixed solutions of textile dyes and to enhance the whitening yield of raw cotton fibers, working in synergism with the conventional H2O2-based method.