1. Department of Microbiology Radboud Institute for Biological and Environmental Sciences, Heyendaalseweg 135 Nijmegen 6525 AJ The Netherlands
2. Netherlands Earth System Science Centre Utrecht University, Heidelberglaan 2 Utrecht 3584 CS The Netherlands
3. Soehngen Institute of Anaerobic Microbiology Radboud University, Heyendaalseweg 135 Nijmegen 6525 AJ The Netherlands
4. School of Environmental Sciences University of Liverpool Liverpool L69 3GP UK