ANME, especially ANME-1, were the most abundant methanotrophs in all metagenomes, except in Tplain, where reads assigned to “candidate division NC10” (assumed to use an “intra-aerobic” methane oxidation pathway [33]) were most abundant (Figure 5). Figure 5 Potential methanotrophic genera detected. The figure

shows potential methanotrophic taxa detected at the genus level. Genera where Troll metagenomes were significantly different from the Oslofjord metagenomes are marked by red arrows. A subset of reads assigned to the taxon “environmental samples, Archaea” P505-15 mw (Significantly underrepresented in Tplain compared to the Oslofjord), further classified as ANME (anaerobic methanotrophic archaea,) are also included. In the STAMP analysis, only MG-132 supplier Tplain displayed significant differences in abundance of known methanotrophic

genera compared to the Oslofjord metagenomes. The gammaproteobacterial genus Methylococcus (aerobic type I methanotrophs) was overrepresented while the abundant taxon “environmental samples, Archaea” was underrepresented in Tplain compared to the Oslofjord metagenomes (Figure 4, Additional file 10: Table S5). Reads assigned to “environmental samples, Archaea” and further to ANME were also two to three times less abundant in Tplain compared to the other Troll metagenomes (Figure 5). Metabolic potential Approximately 12-14% of the reads in O-methylated flavonoid each metagenome were assigned to SEED this website subsystems by MG-RAST (version 2.0) (Additional file 12: Table S7). “Clustering-based subsystems” followed by “Carbohydrates” and “Amino Acids and Derivates”, were the most abundant level I subsystems in all seven

metagenomes. The two Oslofjord metagenomes were highly similar and no significant differences could be detected at SEED subsystem level I in the STAMP analysis. On level III, only two subsystems (“RNA polymerase archaeal initiation factors” and “rRNA modification Haloferax”) were significantly overrepresented in OF2 compared to OF1. Metabolic comparison of the Troll and Oslofjord metagenomes Very few significant differences were detected between the Troll and the Oslofjord metagenomes at SEED subsystems level I in the STAMP analysis. The only significant differences at this level were overrepresentation of the subsystem “Macromolecular Synthesis” in Tplain and underrepresentation of “Prophage” in Tpm3 compared to the Oslofjord metagenomes (Additional file 12: Table S7). At level III however, 79 subsystems were significantly over- or underrepresented in one or more Troll metagenomes compared to the Oslofjord metagenomes (Additional file 13: Table S8). Only one of these (“Archaeal Flagellum”) was significantly underrepresented in all Troll metagenomes compared to the Oslofjord metagenomes.