Fig. 6

Metabolic interactions between microbes. a Metagenomic niche space. Microbial ASVs are plotted on a two-dimensional surface of PCoA based on their KEGG metabolic pathway/process profiles inferred with a phylogenetic prediction of genomes. Microbial ASVs plotted closely within the surface are expected to have similar gene repertoires. The ASVs highlighted in Figs. 4 and 5 are shown with large symbols. b Potential competitive and facilitative interactions. Based on the NCBI RefSeq genome information, potential metabolic interactions between each pair of ASVs were inferred in terms of metabolic resource overlap (MRO) and metabolic interaction potential (MIP). Histograms of MRO and MIP are shown on the horizontal and vertical axes, respectively. ASV pairs including the Cetobacterium ASV, whose abundance was positively associated with eels’ activity level in all the five water tanks (Fig. 3g; Additional file 5: Fig. S5), are shown in pink. Relationships between the Cetobacterium ASV and the ASVs highlighted in Figs. 4 and 5 are indicated as well