1. Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen 6708PB, The Netherlands
2. Cell Biology and Immunology group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen 6708WD, The Netherlands
3. Institute of Biology (IBL), Leiden University, Sylviusweg 72, Leiden 2333 BE, Leiden, The Netherlands