Urease immobilization on alginate-based composite micro-beads

The aim of this research is to investigate the contribution of incorporating Aloe Vera (Aloe barbadensis) (Av), sepiolite (Sp) and carrageenan (Cr) to alginate beads in immobilizing urease enzyme. For this purpose, only alginate (A), AAv, ASp and ACr composite beads were synthesized. Simultaneously, the enzyme-immobilized beads (A-U, AAv-U, ASp-U and ACr-U) were formed by co-synthesis in the presence of urease. All prepared beads were characterized by FTIR analysis and SEM images. The optimum pH and temperature values of the immobilized enzyme activity were determined and compared with those of the free enzyme. The optimum pHs were 7 for free enzyme, AAv-U, Asp-U enzymes, 8 for ACr, and 4.5 for A-U. While the optimum temperature for free enzyme was around 20 °C, immobilized enzymes showed high activity at higher temperatures. In addition, the re-usability and storage stability of the enzyme-immobilized beads were investigated at two different temperatures and in two different environments. Michaelis-Menten constants were determined by studying the variation of enzyme activity with substrate concentration.