Development of a bioreactor system for the decolorization of dyes by Coriolus versicolor f. antarcticus

Decolorization of 100 μM malachite green (MG) by Coriolus versicolor f. antarcticus using a two-phase bioreactor, was investigated. In the first phase the decolorization ability of this fungus, growing under conditions of solid-state fermentation (SSF), was proved; in the second phase the capacity of the enzymes present in extracts from the solid residues was exploited. During the first phase using the same culture in the bioreactor, five consecutive charges were made, each with 75 ml of 100 μM MG solution, at 28 °C. Each cycle ended when MG solution reached a decolorization of 50%, at this time the bioreactor was discharged to a stainless steel coil at 50 °C, initiating the second phase of decolorization. Time required in order to reach 50% decolorization during the first phase varied between 25 and 65 min, with an average retention time of 48 min. The second stage had a retention time of 120 min. Residual MG after this phase varied from 0% to 6.3%. The role of laccase and Mn-peroxidase in MG decolorization is discussed. Toxicity of MG solutions before and after decolorization treatments was assayed using Lumbriculus variegatus as test organism.