title: Laccase-catalyzed decolorization and detoxification of Acid Blue 92: statistical optimization, microtoxicity, kinetics, and energetics.
abstract: BACKGROUND
  In recent years, enzymatic-assisted removal of hazardous dyes has been considered as an alternative and eco-friendly method compared to those of physicochemical techniques. The present study was designed in order to obtain the optimal condition for laccase-mediated (purified from the ascomycete Paraconiothyrium variabile) decolorization of Acid Blue 92; a monoazo dye, using response surface methodology (RSM). So, a D-optimal design with three variables, including pH, enzyme activity, and dye concentration, was applied to optimize the decolorization process. In addition, the kinetic and energetic parameters of the above mentioned enzymatic removal of Acid Blue 92 was investigated.
  
  
  RESULTS
  Decolorization of Acid Blue 92 was maximally (94.1% ± 2.61) occurred at pH 8.0, laccase activity of 2.5 U/mL, and dye concentration of 75 mg/mL. The obtained results of kinetic and energetic studies introduced the laccase-catalyzed decolorization of Acid Blue 92 as an endothermic reaction (Ea, 39 kJ/mol; ΔS, 131 J/mol K; and ΔH, 40 kJ/mol) with K m and V max values of 0.48 mM and 227 mM/min mg, respectively. Furthermore, the results of microtoxicity study revealed that the toxicity of laccase-treated dye was significantly reduced compared to the untreated dye.
  
  
  CONCLUSIONS
  To sum up, the present investigation introduced the Paraconiothyrium variabile laccase as an efficient biocatalyst for decolorization of synthetic dye Acid Blue 92.
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran, 1417614411 Iran.
authors.forename: Shahla
authors.initials: S
authors.lastname: Rezaei
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran, 1417614411 Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Tahmasbi
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran, 1417614411 Iran ; Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran, 1417614411 Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mogharabi
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Alieh
authors.initials: A
authors.lastname: Ameri
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Forootanfar
authors.affiliation: Department of Drug and Food Control, Faculty of Pharmacy and Pharmaceuticals Quality Assurance Research Center, Tehran University of Medical Sciences, Tehran, 1417614411 Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Khoshayand
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran, 1417614411 Iran ; Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran, 1417614411 Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Faramarzi
keywords: Bioremediation; Decolorization; Enzyme Biocatalysis; Laccase; Optimization; Waste Treatment