Table 3. Carbon fixation cycles and main metabolic traits of the C-fixing microorganisms found in this study.

Taxa/phylogeny	C-fixation pathway	Traits	Main genera identified in Lakes Cisó and C-III from the 16S rRNA gene present in the metagenomic pool
Gallionellales Betaproteobacteria	Calvin	Facultative Chemolithoautotroph Energy sources: Fe(II)/sulfide Denitrification	Sideroxydans
Hydrogenophilales Betaproteobacteria	Calvin	Chemolithoautotroph Sulfide oxidation
Campylobacterales Epsilonproteobacteria	Arnona	Chemolithoautotroph Denitrification Sulfide oxidation	Arcobacter, Sulfuricurvum, Sulfurimonas
Chromatiales Gammaproteobacteria	Calvin	Photolithoautotroph Anaerobic Tolerates oxygen	Lamprocystis
Chlorobiales Chlorobi	Arnona	Photolithoautotroph Anaerobic (strict) N fixation	Chlorobium luteolum
Desulfobacterales Deltaproteobacteria	Arnona Reductive acetyl-CoAb	Heterotroph Sulfate reducers	Desulfatiferula, Desulfobulbus, Desulfocapsa, Desulfosalsimonas
Syntrophobacterales Deltaproteobacteria	Arnona Reductive acetyl-CoA(?)b	Heterotroph Sulfate reducer/ sulfide oxidation SRAO	Desulfomonile
Desulfuromonadales Deltaproteobacteria	Reductive acetyl-CoAb	Nitrate dependent Fe(II) oxidation with production of ammonium (Weber et al., 2006)

Abbreviation: SRAO, sulfate-reducing ammonium oxidation.

^aAlso known as reverse Krebs cycle, reverse tricarboxylic acid cycle (rTCA) and reverse citric acid cycle.

^bAlso known as Wood–Ljungdahl pathway.