The main purpose of this work was to use pineapple crowns as substrate for optimizing laccase production by Trametes versicolor in lab-scale experiments. One-factor-at-the-time analysis and response surface methodology were used to optimize production. A single laccase with molecular weight of 45 kDa was the main protein produced. A maximal laccase activity of 60.73 ± 1.01 U/g was obtained in 7-day cultures, representing a 6.7-fold increase compared to non-optimized conditions. The optimized conditions were temperature: 28 °C; initial moisture: 90%; glucose: 8.38%; yeast extract: 2.86%. Combining activity and stability, the best conditions for using this laccase during the long periods required by large-scale processes are pH 4.0-5.0 and temperature of 40-50 °C. Under these conditions, the crude laccase was efficient in detoxifying the dye malachite green with a KM of 14.33 ± 1.94 µM and a Vmax of 0.482 ± 0.029 µM/min with 0.1 units/mL. It can be concluded that pineapple crown leaves can be effectively used as substrate by T. versicolor for producing laccase under solid-state culture conditions. Laccase is an industrially relevant enzyme and its production with concomitant valorization of pineapple crowns as substrate offers highly interesting perspectives.
Keywords: Agricultural waste; ecotoxicity; laccase; pineapple crown leaves; solid state fermentation; synthetic dyes; white-rot fungi.