Immobilization of Kluyveromyces marxianus cells with inulinase in agar.

Abstract

The inulinase-active whole cells of yeast Kluyveromyces marxianus were immobilized by entrapment into agar gel with 76% retention of the enzymatic activity. The enzymatic properties of the immobilized cells were investigated and compared with those of free cells. The immobilization procedure did not alter the optimum pH of the enzymatic preparation. The optimum pH of both free and immobilized cells was 6. The optimum temperature for inulin hydrolysis with the immobilized cells was 5°C higher than that with the free cells. Activation energies for the reaction with the free and immobilized cells were calculated to be 25.62kJ/mol and 13.27kJ/mol, respectively. Km values were 8.3mM inulin for the free cells and 10.5mM for the immobilized cells. Free and immobilized cells showed fairly stable activities between pH 4 to 7 but free cell inulinase was more labile at other pH values compared to the immobilized counterpart. Thermal stability of the enzyme was improved by immobilization. There was no loss of activity of the immobilized cells on storage at 4°C for 30 days.