Decolourisation of a polymeric dye by selected fungal strains in liquid cultures

Eight basidiomycetes were evaluated for their ability to decolourise a polymeric dye, Poly R-478. Decolourisation experiments were carried out in nitrogen-limited (0.25 mM) and nitrogen-rich (5.2 mM) conditions at a dye concentration of 100 mg/L. Stationary liquid cultures were inoculated with mycelium agar plugs and all fungi formed mycelium mats. The effect of nitrogen on decolourisation was also tested in shaken cultures inoculated with homogenized mycelium, where the biomass grew as mycelium beads. In static cultures, all strains apart from Polyporus sp.2 showed better decolourisation in N-rich medium. The greatest removal efficiency was achieved by the fungus Pleurotus ostreatus sp.4, attaining a maximum decolourisation of 53% in 18 days. On the other hand, in agitated cultures all strains were more efficient in decolourisation. The higher levels of removal efficiency were exhibited by Ganoderma australe in N-rich medium, obtaining decolourisation of about 93% in 18 days.