1. Federal Research Centre for Nutrition, Institute for Biotechnology and Molecular Biology, D-76131 Karlsruhe,1 and
2. University of Regensburg, Institute for Microbiology, NWFIII, D-93053 Regensburg,2 Germany, and
3. BCCM/LMG Bacteria Collection, Laboratory of Microbiology, University of Ghent, B-9000 Ghent, Belgium3