Fig. 4: Conceptual figure of bacterial-Phaeodactylum metabolic interactions, based on measurements of C and N incorporation and remineralization by 15 bacterial isolates and remineralization of C and N to (remineralization defined as detectable transfer of remineralized algal-derived DOM to the diatom cells).

Bacteria are classified as macromolecule remineralizers (evidence of nutrient feedback to the diatom cells) or users (no detected N incorporation by diatoms), and bacteria that did not incorporate complex organic N are classified as small-molecule users. Underlined genera have shown evidence of mutualism in co-culture. The thickness of the arrows approximates relative fluxes as measured by isotope incorporation.