Trametes versicolor   growth and laccase induction with by-products of pulp and paper industry

The cultivation of Trametes versicolor for laccase production and cell growth were strongly dependent on experimental conditions namely physical and chemical parameters as well as nutrient availability and inducer stimulation. Biomass growth was compared for a rich medium and for a defined medium in two different temperatures. The best temperature was 28°C and the maximum specific growth rates were μ_max = 0.083 h^-1 for the rich medium and μ_max = 0.043 h^-1 for the defined medium. It was clearly shown that laccase production is not associated with cell growth, indicating that this ligninolytic enzyme must be produced in the defined medium by a secondary metabolism. In order to obtain laccase induction, addition of solid lignin, lignosulphonates, veratryl alcohol, xylidine and ethanol was tested at different concentrations. To optimise laccase activity, the combined effect of inducer addition and simultaneously glucose suppression was studied. The best result for laccase induction (1240 U/L) was obtained with solid lignin, a by-product of pulp and paper industry and the higher laccase activity attained (1583 U/L) was obtained with the combined effect of xylidine addition and glucose suppression.