Aqueous thermostabilization of Pleurotus florida NCIM 1243 laccase and its potential application in Acid Black 10BX dye decolorization: process optimization

In the present investigation, aqueous stabilization of laccase from Pleurotus florida (NCIM 1243) at high temperatures using polysaccharide additives for decolorization of Acid Black 10BX was reported. The stabilization experiments suggest that the combinatorial effect of pectin and carrageenan improved the enzyme stability as compared as individual additives. Hence, combination of pectin and carrageenan were selected to construct an appropriate Response surface methodology (RSM) to enhance the enzyme stability in acidic solutions. Additionally, pH value was taken as a variable to optimize the polysaccharide additives. The optimum values of variables obtained for maximum laccase stabilization at higher temperature are pectin, 0.31%, carrageenan, 0.3% and pH, 4.4 with predicted percentage residual activity of 93.77%. The experimental validation of laccase stabilization was found to be 90.8% using optimized variables. Furthermore, the series of enzymatic dye decolorization experiments were performed to obtain optimum process parameters for maximum decolorization efficiency. Various process parameters such as enzyme concentration (10 U/ml), dye concentration (10 mg/l), temperature (25 °C) and reaction time (150 min) were successfully optimized to achieve maximum decolorization rate. Results of the experimental data reveled that stabilized laccase has the great potential for Acid Black 10BX decolorization at 60 °C than that of native enzyme at pH, 4.4. This investigation enlighten that pectin and carrageenan plays an important role in laccase stabilization and its low cost found to be a good support for large-scale application in biodegradation process.