Separation and recovery of glucose oxidase by adsorption using a macroreticular strong base anion exchange resin

BACKGROUND The commercially available glucose oxidase (GOx) is mainly produced by Aspergillus niger . An efficient and economic recovery technique is practically desired. In this study, various Amberlite™ anion exchange resins were used to separate GOx from buffer solution by adsorption. The obtained optimal pH of 6.8, higher than the isoelectric point of GOx (4.2), indicated the predominant adsorption mechanism of electrostatic interactions between GOx and the resins. RESULTS The adsorption isotherms of GOx on strongly basic IRA‐900 resins at different concentrations of inert salts KCl and NaCl (0.01–0.5 M) and different temperatures (15–35 °C) were measured. All isotherms could be described by the Langmuir equation. Under the conditions studied, a maximum adsorption capacity of 732.8 mg of GOx was obtained per gram of the IRA‐900 resin at 25 °C. Thermodynamic analysis revealed that the current adsorption of GOx was spontaneous with a positive enthalpy change (20.8 kJ/mol) and entropy change (182.5–191.7 J/(mol K)). Increasing the concentration of phosphate buffer eluant and bringing its pH closer to the isoelectric point of GOx gradually increased the desorption efficiency. Also, increasing KCl concentration in the eluant improved the desorption of GOx from the loaded IRA‐900 resins; for example, the desorption approached 100% at 15°C when the eluant comprised 1.0 M of KCl. CONCLUSION This study presents an efficient method to separate and recover GOx from aqueous solution. The screened resin is the macroreticular strong base IRA‐900 with a particle size of 0.074–0.250 mm. Moreover, factors affecting adsorption and desorption of GOx, including pH and concentration of the buffer solution, concentration of inert salt, and temperature, are systematically specified.