Purification and characterization of laccase from Ganoderma lucidum and its application in decolorization of malachite green dye

Abstract

This study describes decolorization of malachite green (MG), one of the recalcitrant and highly used industrial dye, by Ganoderma lucidum MTCC-1039 derived laccase. The extracellular laccase enzyme was purified 3.96-fold to specific activity of 30.55 U/mg by fast protein liquid chromatography. Purified laccase had molecular weight 57 kDa, temperature optima between 40 and 60 °C, pH optima at 5.0 and high thermotolerance and pH stability. The decolorization of MG dye was optimized by Box-Behnken design with incubation temperature, time and pH as independent variables, resulting in 72 % decolorization within 1 h and maximum 91 % decolorization within 3 h, in presence of ABTS as a mediator. Assessment of molecular interaction of the MG-laccase complex by molecular docking analysis indicated significant contribution of Phe 90 and His 243 residues. Moreover, laccase treated MG sample had reduced phytotoxicity indicating its large-scale suitability.