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Laccase production by pre-growth pellets ofTrametes versicolorusing two types of textile dyes as inducers was studied. By decoupling the enzyme production phase from the growth phase, it is possible to reduce the time and nutrients required for laccase production. At the glucose maintenance level, the effect of the nitrogen source and textile dye was analysed using response surface methodology. Ammonium chloride was used as the inorganic nitrogen source. Two types of dyes were tested: Grey Lanaset G (GLG), a metal complex dye mixture containing nitrogen; and Alizarin Red (AR), an anthraquinonic dye with no nitrogen in its chemical structure. GLG induces laccase production at a higher extent than AR. Despite the limiting conditions required for the production of laccase, enzyme production increases with increasing ammonium chloride. When AR, the N-free dye, was used as an inducer, the optimal supply of N for laccase production was 1.2 mg/(g dry cell weight·d) as ammonium chloride. The reuse of fungal pellets in the repeated-batch mode under maintenance conditions was found to be a good strategy for improving laccase production, as enzyme production increased to up to seven times the production of the first cycle. It was demonstrated that GLG can be used as an inducer and as an N source and, thus, it is possible to decolorize the dye and to induce laccase production at the same time without adding an extra N source. [ABSTRACT FROM PUBLISHER]

This work presents the results obtained in the treatment of industrial pulp mill wastewater (black liquor) with the white-rot fungus Trametes versicolor immobilised in nylon and polyurethane foam cubes. Reductions in colour (36%), aromatic compounds (54%) and toxicity (3.15 times reduction of the initial value) were obtained when the fungus was immobilised in nylon and good toxicity reduction (5.7-fold reduction of the initial value) when polyurethane foam was used. These results were compared with those obtained with Trametes versicolor in the form of pellets for colour and aromatic compounds (84.8% and 70.2% respectively). Correlations among different parameters have been studied. Relationships between colour and changes in the molecular weight distribution profiles, as well as a correlation between laccase production and toxicity reduction have been found. For laccase production vs. toxicity reduction a different behaviour has been observed depending on the bioreactor configuration (fixed-bed reactor with immobilised Trametes versicolor or fluidised bed reactor with pellets of Trametes versicolor). [ABSTRACT FROM AUTHOR]