1. Department of Geochemistry, Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark, Department of Microbiology, University of Copenhagen, Sølvgade 83H, DK-1307 Copenhagen K, Denmark, Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark, Department of Life Sciences and Chemistry, Roskilde University, Postboks 260, DK-4000 Roskilde, Denmark, and Institute of Food...