BackgroundStudies were carried on the decolorization of the textile dye reactive blue 19 (RB 19) by a novel isolate of Coprinus plicatilis (C. plicatilis) fungi. We describe an in vitro optimization process for decolorization and its behavior under different conditions of carbon and nitrogen sources, pH, temperature and substrate concentration.ResultsThe optimal conditions for decolorization were obtained in media containing intermediate concentrations of ammonium oxalate and glucose (10 g/L) as nitrogen and carbon sources, respectively, at 26°C and pH = 5.5. Maximum decolorization efficiency against RB 19 achieved in this study was around 99%. Ultra-violet and visible (UV-vis) spectrophotometric analyses, before and after decolorization, suggest that decolorization was due to biodegradation.ConclusionsThis effect was associated with laccase enzyme displaying good tolerance to a wide range of pH values, salt concentrations and temperatures, suggesting a potential role for this organism in the remediation of real dye containing effluents. In conclusion, laccase activity in C. plicatilis was firstly described in this study.

To investigate biodegradability by Trametes versicolor, five structurally different direct azo-dyes-Direct Black 38, Direct Blue 15 (DB 15), Direct Orange 26, Direct Green 6, and Direct Yellow 12-were studied. The DB 15 was determined as the best biodegradable dye by this white-rot fungus. Laccase and manganese peroxidase activities were monitored with the biodegradation process; it was observed that laccase played an important role in the dye degradation, while manganese peroxidase activity could not be detected. Possible degradation products also were examined by gas chromatography-mass spectrometry, but no metabolite was detected after the degradation and/or decolorization process. To enhance performance of the fungi during the degradation, Trametes versicolor cells were immobilized in alginate beads. Then, DB 15 decolorization by immobilized Trametes versicolor was studied in a small-scale packed-bed reactor. The color removal efficiency in repeated batches was found to be 98 and 93% for 50 mg/L DB 15. Water Environ. Res., 82, 579 (2010).

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In traditional separation processes, there are environmental risks still because of the presence of toxic agents. Thus, a novel biomembrane microreactor named eco-green biomembrane (EgBM) was developed to perform the transport, biodegradation, and cleaning of a textile dye aqueous solution (3 mg/L) from the donor (i.e., textile dye) to the acceptor (i.e., laccase enzymes) phases. In the present work, Morchella esculenta pellets were used as carriers and degraders instead of using the traditional chemical carriers. The optimized EgBM was made of cellulose triacetate (16.1%) as a base polymer, 2-nitrophenyl octyl ether (25.2%) as a plasticizer, and M. esculenta fungus pellets (58.7%) as both carriers and degraders. A decoloration percentage of 98.6% ± 0.8 in 60 h was attained, which was due to two mechanisms: biosorption (15.4% ± 0.1) on fungal mycelium and biodegradation (83.2% ± 0.6) by laccase enzymes. The EgBM was achieved not only by the transport of reactive textile dyes used in the donor phase but also by the biodegradation and biosorption of the dyes.

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