Fat hydrolysis in water immiscible organic solvent system by microbial lipase

Abstract

Two phase system was examined on the possibility applicable to the enzymatic fat splitting process so as to broaden the substrate range up to solid fats and to enhance the productivity. Organic solvent utilized in two phase system was necessarily water-immiscible so that the enzyme might not be inactivated by hydrophobic denaturation. The lipase activity was maximum in two phase system comprised iso-octane at 35℃ and pH 6.0, and the activation energy of the lipase was 10.1 Kcal/mole. The lipase activity was examined for tripalmitin of the model as solid fat. The result indicated that the lipase activities in two phase system was 2-3 times higher than in water system, and the discrepancy of the lipase activity between two systems was increased. Apparent Vm and Km of the soluble lipase in two phase system were 16.7 umole/ml/hr and 25 mmole on tripalmitin, respectively. The effect of carrier types of immobilized lipase was examined in two phase system. While the optimum pH of hydrophilic gel entrapped lipase (ENT-4000) was pH 7.0, the reaction rate of the hydrophobic gel entrapped lipase was less dependent to pH variations. In latter case, stability was slightly enhanced at pH 7. As a degree of hydrophobicity of the immobilized matrix was increased, $Vm_{(app)}$ was increased for 2.17 to 3.35 umole/ml/hr, but $Km_{(app)}$was approximately constant in the range of 17.6-18.8% $\frac{v}/{v}$. Thus, the reaction rate of the immobilized lipase was increased as the degree of hydrophobicity of the immobilized matrix was increased. i.e. polarity of microenvironment of lipase was decreased.