Decolorization of synthetic dyes by Irpex lacteus in liquid cultures and packed-bed bioreactor

Abstract

White rot fungus Irpex lacteus was grown in both stationary and agitated submerged liquid cultures as well as in cultures immobilized on polyurethane foam (PUF) and pine wood (PW) to study the effect of growth conditions on degradation of commercial dyes. The respective values of decolorization of the anthraquinone-based Remazol Brilliant Blue R (RBBR) dye used at 150 μg ml −1 were 100, 95, 97 and 100% within 6–10 days. Stationary cultures exhibited higher levels of lignin peroxidase (LiP), manganese-dependent peroxidase (MnP) and laccase than submerged cultures and selective inhibition by NaN 3 and n-propylgallate brought evidence that MnP played a major role in the decolorization of RBBR by I. lacteus. When comparing PUF- and PW-immobilized cultures decolorizing RBBR, five-fold MnP levels were detected in the former cultures whereas laccase activities were similar. No LiP was detected in either immobilized culture. Both immobilized cultures were able to rapidly decolorize not only RBBR but also various textile-industry, color bath effluents. Reusability and regenerative capacity of the immobilized cultures, important for application to water bioremediation, were documented.