Fig. 3.

A. glacialis A3 preferentially promotes growth of Roseobacters by secreting specific metabolites that influence bacterial growth and behavior. Summary of diatom–bacteria interactions highlighting the metabolic exchanges and differentially expressed (DE) genes in A. glacialis A3 and three Roseobacter MAGs. Small colored circles (red, up-regulation; blue, down-regulation; white, no DE) represent differential expression of genes/processes at 0.5 (Left) and 24 (Right) hours after reseeding. Differential expression of metabolic cycles indicates that at least one gene was DE in one direction while no other genes were DE in the opposite direction. A complete list of genes and expression values are in SI Appendix, Tables S3 and S5. Confirmed central and secondary molecules from the exometabolome (SI Appendix, Table S4) are shown between the cells, and their relative abundance is indicated by colored circles relative to axenic controls. Multiple stacked arrows indicate several enzymatic reactions. SAMamine, S-adenosylmethionineamine; Carb-P, carbamoylphosphate; Cit, citrulline; α-KG, α-ketoglutarate; Pyr, pyruvate; Arg-succ, argininosuccinate; Arg, arginine; Orn, ornithine; PEP, phosphoenolpyruvate; 3-PGA, 3-phosphoglycerate; 1,3-GP, glycerate 1,3-diphosphate; PS, photosystem genes; O-isoval, o-isovalerate; IPM, isopropylmalate; Asp, aspartate; Glu, glutamate; Gln, glutamine; Leu, leucine; Thr, threonine; Trp, tryptophan; BCFA, branched-chain fatty acids; DHPS, 2,3-dihydroxypropanesulfonate; ARGs, antibiotic resistance genes; DCT, dicarboxylate transporter; DMSP, dimethylsulfoniopropionate; AI-2, autoinducer-2; MCT, monocarboxylate 2-oxoacid transporter; Phns, phosphonates; AHL, acyl homoserine lactones; IAA, indole-3-acetate.