Purification of thePenicillium citrinum Lipase Using AOT Reversed Micelles

Abstract

This work describes the extraction and back-extraction of a lipase from crude extract of Penicillium citrinum using AOT reversed micelles in isooctane. The effect of pH, ionic strength, AOT concentration on the protein forward and backward transfer at 20°C was studied. The maximum protein forward extraction (32·0%) was achieved at pH 4·0 with a 50 mmol dm−3 acetate buffer containing 100 mmol dm−3 KCl and 100 mmol dm−3 AOT in isooctane. Proteins were back-extracted (82·7%) to a new aqueous phase containing 100 mmol dm−3 pH 8·0 phosphate buffer and 1000 mmol dm−3 KCl. No enzyme activity could be detected either in the micellar phase or in the aqueous phase after protein back-extraction. However, the lipolytic activity was recovered after hydrophobic interaction chromatography on a Phenyl Superose column. The yield obtained for the overall process was 68% for activity, 26·4% for protein recovery and the purification factor was 810-fold. A single protein band at 33000 Da was obtained for SDS–PAGE analysis for the recovered and purified enzyme. © 1997 SCI.