1. Department of Fundamental Microbiology; University of Lausanne; Lausanne Switzerland 1015
2. Department of Biotechnology Faculty of Applied Sciences; Delft University of Technology; Delft 2629 HZ The Netherlands
3. Department of Mathematics; University of Fribourg, CH-1700; Fribourg Switzerland
4. Microsystems Laboratory LMIS4; École Polytechnique Fédérale de Lausanne (EPFL), Station 17; Lausanne Switzerland CH-1015