Selection of a support for immobilization of a microbial lipase for the hydrolysis of triglycerides

Baterial lipase from Staphylococcus carnosus (pLipMut2) has been immobilized on various supports in order to determine a suitable immobilization technique in terms of activity and stability, when utilized for the hydrolysis of tributyrin. The hydrophobic materials PBA Eupergit and PBA Eupergit 250L prooved to be appropriate supports, when the enzyme was crosslinked with glutaraldehyde after adsorption. No desorption of the immobilized enzyme occured during operation. The pore size of the support has a strong effect on the activity but does not influence stability.The initial activity for immobilized and soluble lipase is found to follow the Arrhenius equation at low temperature, where mass transfer does not affect reaction kinetics. Activation energies for soluble and immobilized lipase were evaluated to be 21.7 kJ mol^–1 and 60.8 kJ mol^–1, respectively.Operational stability was studied in a packed bed recirculation reactor. Thermal desactivation followed first order kinetics with a half-life of 1340 h at 10°C. Model calculations for productivity showed, that optimal temperatures for high productivity are well below the temperature of maximal activity.List of Symbols E _a kJ mol^–1] activation energy - E _d kJ mol^–1] activation energy of desactivation - H –] half-number - k _d h^–1] desactivation constant - k _d, h^–1] constant - k _N –] desactivation constant (number) - N –] number of runs - p mol dm^–3] productivity - t h] time - t _0.5 h] half-life - T K] absolute temperature - V U ml^–1] activity - V(N) Uml^–1] activity exhibited in the n-th run - V _s,O U ml^–1] initial activity of supernatant - V _s, U ml^–1] activity of supernatant after immobilization - V _O U ml^–1] initial activity - V U ml^–1] constant - _imm –] activity yield - ml ml^–1] ratio of volume of support to volume of supernatant Financial support of this work by the Deutsche Forschungsgemeinschaft (SFB 145, A15) is gratefully acknowledged.