1. Laboratory of Microbiology, Department of Biochemistry, Physiology and Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
2. Nestlé Research Centre, Route du Jorat 57, Vers-Chez-Les-Blanc, 1000 Lausanne 26, Switzerland
3. BCCM/LMG Bacteria Collection, Department of Biochemistry, Physiology and Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium