BACKGROUND: Phanerochaete chrysosporium, Trametes versicolor and Bjerkandera sp BOL13 were compared for decolorization of azo dyes supplied individually or as a mixture. The dye decolorization was also evaluated during continuous treatment under non-sterile conditions using a lignocellulosic growth substrate. RESULTS: Bjerkandera sp BOL13 showed the highest dye decolorization potential. This fungus was also found to support high decolorization of Remazol Red RR at an initial pH of 4-6 and when using straw as co-substrate. The fungus was evaluated for Remazol Red RR decolorization in a continuously fed packed-bed bioreactor operated under non-sterile conditions with 3 days of hydraulic retention time. When glucose was supplied as growth-substrate, decolorization efficiencies of 65-90% were maintained for 12 days in a bioreactor packed with wooden material. The decolorization efficiency was lower when glucose was not fed to the fungus or when a plastic material was used as packing. Higher manganese peroxidase and laccase activities were also recorded when the wood packing was used. Contamination caused a drop in decolorization efficiency after 17-19 days operation. CONCLUSIONS: The potential of Bjerkandera sp BOL13 for decolorization of azo dyes under non-sterile conditions using lignocellulosic growth substrates was demonstrated. Research is needed to reduce contamination under non-sterile conditions. (c) 2012 Society of Chemical Industry