1. Center of Biomembranes and Lipid Enzymology, Department of Biochemistry of Membranes, Institute for Biomembranes, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands.
2. Institute for Medical Microbiology and Immunology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany.
3. NIZO Food Research, Microbial Ingredients Section, Post Office Box 20, 6710 BA Ede, Netherlands.
4. Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Post Office Box 14, 9750 AA Haren, Netherlands.