The mature UpI gene, encoding the lipase I from Galactomyces geotrichum BT107, was obtained by PCR from genomic DNA, sequenced and cloned into a Pichia pastoris expression vector. Clones containing multiple copies of lipI integrated in their genome were analyzed to achieve high-level expression of the recombinant lipase I. One strain with four or more copies of the expression cassette was able to produce more than 200 mg/L of extracellular heterologous protein. The lipase I was partially purified using anion exchange chromatography and its activity on monounsaturated (triolein) and polyunsaturated (triEPA) triglycerides was analyzed by a novel HPLC-MS assay. (c) 2006 Elsevier Inc. All rights reserved.