1. Helmholtz Centre for Environmental Research – UFZ, Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany. Fax: +49 341 235 1443; Tel: +49 341 235 1435
2. Chair of Geobiotechnology, Technische Universität Berlin, Berlin, Germany
3. Helmholtz Centre for Environmental Research – UFZ, Department of Analytical Chemistry, Leipzig, Germany
4. Institute of Biology/Microbiology, Martin-Luther Universität, Halle, Germany