Removal of phenols from acidic environment by horseradish peroxidase (HRP): Aqueous thermostabilization of HRP by polysaccharide additives

• Aqueous thermostabilization of HRP using polysaccharide additives under acid pH.
• HRP stability in acidic solutions was enhanced by using RSM.
• HRP was stabilized in the presence of dextran, sodium alginate and sodium acetate buffer.
• DSC measured the thermal denaturation of HRP with and without additives.
• The stabilized HRP successfully removes phenols under acid pH.

The bio-productive property of combinatorial polysaccharide additives (dextran and sodium alginate) on stability of horseradish peroxidase (HRP) for removal of phenols from acidic solutions was studied in this paper. The optimum pH range and temperature were determined for the stabilized enzyme as 3.6–5.4 and 65 °C, respectively. Enzyme stabilization experiments were conducted in the solution state without enzyme immobilization or encapsulation. The combinatorial polysaccharides were selected to construct an appropriate response surface methodology (RSM) for maximum HRP stabilization together with sodium acetate buffer to optimize the polysaccharide additives. The RSM results suggest 10.08% of dextran, 0.41% of sodium alginate and 64 mM sodium acetate buffer for maximum HRP stabilization at 65 °C with a predicted percentage residual activity of 60.01%. DSC results corroborated that the denaturation temperature (TD) values of stabilized HRP to be 30 °C higher than that of the native enzyme. The effect of pH on phenol removal for both native and stabilized HRP suggested that stabilized HRP exhibited high phenol removal activities even under acidic environment and successfully removed phenols.