INVERT EMULSION AS A MEDIUM FOR FUNGAL LIPASE ACTIVITY

An extracellular lipase from the fungus Pythium ultimum was active in an invert [water-in-oil] emulsion consisting of 4% water emulsified in to edible oils with taurocholic acid as the surfactant. The pH range f or optimum lipolytic activity was 7.5-8.5, and the optimum temperature for activity was 45 degrees C. Specific activity of the purified lipa se was 919.5 mu mol/min/mg protein in the invert emulsion. Water conte nt of the invert emulsion influenced activity of the lipase differentl y, depending on the substrate. The rate of olive oil hydrolysis with t he Pythium lipase decreased with time, possibly due to inactivation of the enzyme and inhibition by free fatty acid products of the reaction . Total hydrolysis of olive oil by the Pythium lipase was compared wit h that by lipases from Candida rugosa and Rhizopus arrhizus in the inv ert emulsion. Hydrolysis essentially ceased within 24 h or less for th e lipases from each source. However, the addition of aqueous solution at 8 h from the beginning of incubation stimulated hydrolysis by C. ru gosa and R. arrhizus lipases by 1.8-fold and 2.5-fold, respectively, b ut not by the P. ultimum lipase, over corresponding controls after 48 h.