Fig. 4.

Overview of the main known metabolic abilities (carbon fixation, ferrous iron oxidation and sulfur metabolism) of microbial community and environmental adaption in surface-layer mine tailings. This figure was adapted from the previous models [26, 40, 52, 61]. All possible subsystems are depicted in the quarters of each image. In the CO₂ fixation, enzymes associated with rTCA cycle are indicated by numbers: 1, malate dehydrogenase; 2, fumarate hydratase; 3, fumarate reductase; 4, succinyl-CoA synthetase; 5, 2-oxoglutarate ferredoxin oxidoreductase; 6, isocitrate dehydrogenase; 7, aconitase hydratase 1; 8, citryl-CoA synthetase; 9, citryl-CoA lyase; 10, pyruvate ferredoxin oxidoreductase. The enzymes related to nitrogen metabolism, ferrous iron oxidation and sulfur metabolism as abbreviated forms are depicted. Abbreviations: R: Rusticyanin; SQR: sulfide quinone reductase; TQO: thiosulfate:quinone oxidoreductase; TetH: tetrathionate hydrolase; SOX: sulfur oxidizing protein; HDR: heterodisulfide reductase; SOR: sulfur oxygenase reductase; TST: thiosulfate sulfurtransferase; SO: sulfite oxidase; APR: adenylylsulfate reductase; SAT: sulfate adenylyltransferase; CysC: adenylylsulfate kinase; CysH: phosphoadenosine phosphosulfate reductase; CysJI: sulfite reductase (NADPH) flavoprotein; SIR: sulfite reductase (ferredoxin); DsrAB: sulfite reductase