FIG 2 .

Linear relationships between the levels of abundance of specific functional gene families and log-transformed Uranium (A to D) or nitrate (E to H) concentrations in groundwater, including data for dsrA, encoding the alpha subunit of sulfite reductase for dissimilatory sulfite reduction (A), sqr, encoding sulfide-quinone reductase (B), cytochrome genes from well-known organisms, e.g., Geobacter, Anaeromyxobacter, Dechloromonas, Desulfovibrio, Shewanella, Desulfurobacterium, Desulfobacterium, Rhodobacter, Pseudomonas, Enterobacter, and Ochrobactrum (C), hydrogenase genes from well-known organisms, e.g., Geobacter, Desulfovibrio, Desulfurobacterium, Desulfobacterium, and Rhodobacter (D), nirK, encoding nitrite reductase for denitrification (E), nosZ, encoding nitrous oxide reductase for denitrification (F), napA, encoding nitrate reductase for dissimilatory nitrate reduction (G), and nasA, encoding nitrate reductase for assimilatory nitrate reduction (H).