Decolorization of some synthetic dyes using optimized culture broth of laccase producing ascomycete Paraconiothyrium variabile

Optimization of the medium components for production of laccase by Paraconiothyrium variabile using response surface methodology was investigated. Initial screening by Plackett-Burman design was performed to select major variables out of eleven medium components, among which peptone. CuSO4, and xylidine were found to have significant effects on laccase production. After application of the steepest ascent to approach the proximity of the optimum point, a central composite design was employed to optimize the level of the selected variables. In optimum concentrations of the most effective parameters, including peptone, 2.2 g/L, CuSO4, 0.03 g/L, and xylidine 1.29 mM, extracellular laccase activity was enhanced from 970 U/L (in basal medium) to 16,678 U/L, which means a 17-fold increase in laccase production in the optimized medium. Supernatant of the optimized medium was used for decolorization of five synthetic dyes, among which 93% of Remazol brilliant blue R (with initial concentration of 600 mg/L) disappeared after 3 h treatment in the presence of 5 mM hydroxybenzotriazole. (C) 2011 Elsevier B.V. All rights reserved.