Simultaneous production of laccase and decolouration of the diazo dye Reactive Black 5 in a fixed-bed bioreactor

• Published in: Journal of hazardous materials Vol. 164; no. 1; pp. 296 - 300
• Main Authors: Enayatzamir, Kheirghadam, Alikhani, Hossein A., Rodríguez Couto, Susana
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.05.2009; Elsevier
• Subjects: Adsorption; Applied sciences; Biodegradation, Environmental; Biological and medical sciences; Bioreactors; Biotechnology; Chemical engineering; Coloring Agents - chemistry; Exact sciences and technology; Fixed-bed reactor; Fundamental and applied biological sciences. Psychology; Laccase; Laccase - biosynthesis; Methods. Procedures. Technologies; Naphthalenesulfonates - chemistry; Others; Pollution; Reactive Black 5; Reactors; Stainless steel sponges; Trametes - enzymology; Trametes - metabolism; Trametes pubescens; Various methods and equipments; Waste Disposal, Fluid - methods; Stainless steel sponges; Reactive Black 5; Trametes pubescens; Fixed-bed reactor; Laccase; Biodegradation; Pollutant behavior; Fixed bed reactor; Extract; In vitro; Biological purification; Bioreactor; Adsorption; Batchwise; Stainless steel; Reactive dye; Production; Fixed bed
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2008.08.032

In this paper the production of laccase and the decolouration of the recalcitrant diazo dye Reactive Black 5 (RB5) by the white-rot fungus Trametes pubescens immobilised on stainless steel sponges in a fixed-bed reactor were studied. Laccase production was increased by 10-fold in the presence of RB5 and reached a maximum value of 1025 U/l. Enhanced laccase production in the presence of RB5 in this fungus is an added advantage during biodegradation of RB5-containing effluents. The decolouration of RB5 was due to two processes: dye adsorption onto the fungal mycelium and dye degradation by the laccase enzymes produced by the fungus. RB5 decolouration was performed during four successive batches obtaining high decolouration percentages (74%, 43% and 52% in 24 h for the first, third and four batch, respectively) without addition of redox mediators. Also, the in vitro decolouration of RB5 by the concentrated culture extract, containing mainly laccase, produced in the above bioreactor was studied. The decolouration percentages obtained were considerably lower (around 20% in 24 h) than that attained with the whole culture.