1. Wageningen Centre for Food Sciences, 6700 AN Wageningen
2. Laboratory of Microbiology, Wageningen University, 6703 CT Wageningen
3. University of Kuopio, Institute of Applied Biotechnology, FIN-70211
4. Harjula Hospital, FIN-70100, Kuopio, Finland
5. Laboratory of Food Microbiology, 6700 EV Wageningen, The Netherlands