Thermokinetic Comparison of Trypan Blue Decolorization by Free Laccase and Fungal Biomass

Abstract

Free laccase and fungal biomass from white-rot fungi were compared in the thermokinetics study of the laccase-catalyzed decolorization of an azo dye, i.e., Trypan Blue. The decolorization in both systems followed a first-order kinetics. The apparent first-order rate constant, k1', value increases with temperature. Apparent activation energy of decolorization was similar for both systems at ∼ 22 kJ mol(-1), while energy for laccase inactivation was 18 kJ mol(-1). Although both systems were endothermic, fungal biomass showed higher enthalpy, entropy, and Gibbs free energy changes for the decolorization compared to free laccase. On the other hand, free laccase showed reaction spontaneity over a wider range of temperature (ΔT = 40 K) as opposed to fungal biomass (ΔT = 15 K). Comparison of entropy change (ΔS) values indicated metabolism of the dye by the biomass.

Purification and characterization of laccase from Pleurotus tuber-regium and its application in dye decolourization

“…It was also observed that the trypan blue dye was decolourized faster and better (65%) than the Congo red dye (28.85%) in the liquid media after 4 h of incubation. A similar percentage of decolourization of trypan blue dye was reported for a commercial laccase (62%) (Razak and Annuar, 2014), while 42% and 25% have been reported for laccase from Daedalea quercina and a marine fungus respectively (Baldrian., 2004;D'Souza et al, 2006). It has been established in a previous study that fungal biomass system and purified laccase could be applied in bio-decolourization processes (Razak and Annuar, 2014).…”

“…A similar percentage of decolourization of trypan blue dye was reported for a commercial laccase (62%) (Razak and Annuar, 2014), while 42% and 25% have been reported for laccase from Daedalea quercina and a marine fungus respectively (Baldrian., 2004;D'Souza et al, 2006). It has been established in a previous study that fungal biomass system and purified laccase could be applied in bio-decolourization processes (Razak and Annuar, 2014). The use of the fungal biomass system implies the removal of dyes through their adsorption to the fungi mycelia or intracellular secretion of laccase which then aids in dye biodegradation.…”

“…With catechol and guaiacol, the K m values were 6.456 and 32.39 mM respectively while the V max values were 1.349 and 12.5 mM, respectively. Previous observations have shown that the lower the K m value, the higher the affinity of the enzyme for the substrate (Razak and Annuar, 2014). Moreover, the higher the V max , the smaller the quantity of enzyme necessary to convert a substrate into a product (Noreen et al, 2016).…”

Development of strong enzymatic biocatalysts for dye decolorization

“…Immobilized laccase exhibited a strong decolorization capacity at short reaction times without mediator addition. Results significantly higher than those reported previously for Trypan Blue (Razak and Annuar, 2014), Bromothymol Blue (Ling et al, 2015) and Methyl Orange (Pardo et al, 2013) among others, showing the potential of immobilized biocatalyst developed.…”

Decolorization of selected azo dye by Lysinibacillus fusiformis W1B6: Biodegradation optimization, isotherm, and kinetic study biosorption mechanism

“…Laccase activity was measured according to Razak and Annuar (2014). The assay mixture contained 2.5 mL of phosphate-citrate buffer (0.1 M), 0.1 mL of syringaldazine (5 mM) and 0.5 mL of the enzyme solution.…”