FIG 3.

Integrated metaproteomics and metabolomics suggest carbon transformations expressed by bacterial and archaeal lineages in river sediments. Background blue shading spans polymers (top) to single-carbon compounds (C₁; bottom) (arrow on left). Detected metabolites are shown in boxes, with NMR-detected compounds indicated in red type, polymers from FTICR-MS in orange type, and undetected metabolites in black type. MAG-resolved metaproteome information is indicated by solid arrows, with MAG icons colored by phylum. Pink arrows indicate processes that are expressed and could contribute to CO₂ production, while black arrows indicate other carbon-transforming genes expressed in the proteome. Dotted arrows represent transformations supported by only one method: (i) gray dotted arrow indicates metabolites and downstream products (but no proteome support) and (ii) pink dotted arrow indicates metaproteomic evidence (but no geochemistry or metabolite support).