Flow diagram of the potential interactions between (left to right) organic carbon utilization, fermentation, and respiration identified in the bacterial genomes reconstructed in this study. Arrows represent metabolic capabilities that were identified in the metagenomic reconstruction from the White Oak River estuary. The dashed lines on the right represent potential electron donors for the anaerobic respiration processes. Note that the Gammaproteobacteria are capable of coupling nitrate reduction to either thiosulfate or sulfide oxidation. Abbreviations in the diagram are as follows; DNRA, dissimilatory nitrate reduction to ammonia; ‘Betaprot’, Betaproteobacteria; ‘Deltaprot’, Deltaproteobacteria; ‘Gemmatio’, Gemmatimonadetes (‘Gemm38-2’ refers specifically to bin 38-2), ‘Gammaprot’, Gammaproteobacteria; ‘Myxococca’, Myxococcales; ‘Plancto’, Planctomycetes.