Entrapment of protease from Bacillus sp. in polyvinyl alcohol hydrogels

Abstract

This study highlights the effective immobilization of protease from Bacillus sp. in polyvinyl alcohol hydrogels and its characterization. Both free and entrapped proteases exhibited optimal activity at pH 8.0 and 55°C, indicating that the immobilization did not significantly alter the enzyme's fundamental properties. The entrapment in polyvinyl alcohol hydrogels significantly enhanced thermal stability. After 24 hours at 55°C, the free protease retained only 19% of its initial activity, whereas the entrapped protease retained 72%. The entrapped protease showed a longer half-life of 53.3 hours compared to 10.6 hours for the free protease. The Km and Vmax values of free protease were determined to be 0.5 mg/mL and 23.3 U/mg protein, respectively, for casein. These values were found to be 0.2 mg/mL and 23.8 U/mg protein, respectively for the entrapped protease. The entrapped protease retained 58% of its initial activity after 5 reuses in a batch reactor. As a result, the entrapment of Bacillus sp. protease in polyvinyl alcohol is an effective immobilization method due to its simplicity, low cost, and ability to provide a 5-fold increase in thermal stability.