1. Laboratory of Food Biotechnology, Institute of Food, Nutrition and Health, ETH Zurich , 8092 Zurich , Switzerland
2. Danone Global Research & Innovation Center , 91190 Gif sur Yvette , France
3. Present address: Department of Microbiology and Immunology , Laboratory of Molecular Bacteriology, , 3000 Leuven , Belgium
4. Rega Institute KU , Laboratory of Molecular Bacteriology, , 3000 Leuven , Belgium