Efficacy and Recovery of Cellulases Immobilized on Polymer Brushes Grafted on Silica Nanoparticles

Abstract

Cellulosic biofuels can be more economical if cellulases are recovered and reused. Cellulase and β-glucosidase were immobilized on poly(acrylic acid) brush particles. Impact of brush enzyme density on efficacy and recovery was tested. Use of free enzymes led to higher sugar concentrations than the attached for both the enzymes. Increasing cellulase density on the brushes did not impact efficacy. Higher proportions of cellobiose in hydrolyzates suggest differential attachment or efficacy of attached enzymes. Higher β-glucosidase density on brushes led to increased glucose concentrations. Density on brushes did not impact β-glucosidase recovery and [approximately] 66% was recovered. Effect of pH and temperature on hydrolysis rates and enzyme recovery was modeled. Free β-glucosidase was more stable with temperature than attached. Optimal pH for attached cellulase and β-glucosidase was 4.98 and 4.39, respectively. Recovery of β-glucosidase decreased with increasing pH and was not impacted by temperature.