Fig. 3

Schematic diagram of nitrogen metabolism in the surface-layer mine tailings representing one important part of bioleaching system. On the basis of metagenomic data, solid lines indicate the presence of protein-coding genes associated with six major pathways, whereas dashed lines show that no gene was found in this metagenome. Different colored lines depict various metabolic pathways. Most main implicated taxa/groups governing the enzymatic reactions are displayed respectively, and the percentages of CDSs related to each group are also showed. Abbreviations: nif, nitrogenase (various subunits); amo: ammonia monooxygenase; hao: hydroxylamine dehydrogenase; norAB: Nitrate reductase (A and B represent alpha subunit and beta subunit, respectively); narGHIJ: nitrate reductase (dissimilartory); nirK: nitrite reductase (NO-forming); norBC: nitric oxide reductase; nosZ: nitrous oxide reductase; nasAB: nitrate reductase (assimilatory); nirA: ferredoxin-nitrite reductase; nirBD: nitrite reductase (NADH); hzo: hydrazine oxidoreductase