Ester Exchange of Fats and Oils by Microbial Cells as Catalyst

Abstract

Microbial cell-bound lipases were used as catalysts for ester exchange between fats and fatty acids in an organic solvent to modify the properties of fats and oils. A yeast (Saccharomycopsis lipolytica) and an unknown bacterium were selected to test catalytic activities. The cells were cultured in optimized media, washed with 0.85% NaCl and an organic solvent and then dried to prepare cell powder.We determined the amount of added fatty acid incorporated into the triglyceride fraction. Among the fatty acids examined, the yeast cells catalyzed most quickly the incorporation of oleic acid, while the bacterium cells showed specificity for cis-9-hexadecenoic acid (palmitoleic acid). The latter cells showed very weak activity toward oleic acid (11% the activity toward palmitoleic acid). The yeast cells catalyzed the reaction best at pH 8.0 and 35°C.The water content of the reaction mixture was an important factor affecting the ester exchange. The optimum concentrations were 1.0 and 0.25%(wt/wt) for the yeast and bacterium cells, respectively.