Fig. 4: The summary of carbon fixation and energy metabolisms along vertical gradient in the world’s deepest blue hole.

a The overview of carbon fixation pathways and representative clades along vertical gradient. Cycle circles represent distribution of different carbon fixation pathways, and the colored dots were eight representative clades nearby. The box is the possible source of electron donors and electron acceptors for carbon fixation in different layers. The big arrow reflected the tendency of mixotrophy for these clades from the top to the bottom. b The inferred metabolic capabilities in eight representative MAGs. Predicted metabolic pathways and corresponding genes that may drive carbon fixation in eight representative MAGs are indicated by colored dots to demonstrate the comparison between clades. Metabolic pathways included carbon fixation, sulfur, nitrogen metabolisms and carbohydrate degradation. The colored ellipse represent oxidation, reduction reaction and disproportionation. The white dots represent missing this pathway.