Fig. 2

Metagenomic and COG composition of the studied sections of the Amazon River microbiome. Ordination of metagenomes composing the different river sections based on the Jaccard distances calculated from the presence-absence of k-mers in each sample (a-c). NMDS groups were statistically different [PERMANOVA, F = 2.34, p value = 9.99e−5] (a), displaying intragroup heterogeneity [β dispersion; PERMUTEST, F = 7.72, p value = 0.001] (b). Metagenomic composition of the Amazon River microbiome according to microbial lifestyle (free-living (FL) vs. particle-attached (PA)) (c). NMDS groups were statistically different [PERMANOVA, F = 3.62, p value = 0.06], displaying intragroup homogeneity [β dispersion; PERMUTEST, F = 3.62, p value = 0.074]. COG composition across size fractions and sections of the Amazon River (d). Gene functions grouped into COG superclasses are shown per river section and microbial lifestyle (free-living vs. particle-attached). The Upstream river section is not shown in the particle-attached fraction since it was not sampled