Fig. 6: Members of novel chlamydial families predominantly occur in freshwater and marine environments.

a 16S rRNA gene maximum likelihood phylogenetic tree using near full-length sequences de-replicated at 99% under the SYM + R10 model inferred with IQTREE. Support was inferred from transfer bootstrap expectation (TBE) based on 100 non-parametric bootstraps. Circles at nodes indicate TBE support ≥70. The tree is pruned and does not include the outgroup. Chlamydial families are highlighted by gray background, 16S rRNA genes from novel MAGs in this study are indicated by orange shading. b All chlamydial full-length 16S rRNA genes in chlamydial genomes were used as a query against IMNGS with an identity cutoff of 1% to ensure species-specificity and summarized at the family level. Stars next to names indicate families with cultured representatives. Environmental categories “marine” and “freshwater” represent samples originating from the water column. The scatter plot on the left shows the relative abundance of chlamydial 16S rRNA gene amplicons. The bar plot in the middle shows the relative distribution of family members across diverse environments. The bar plot on the right indicates significant enrichment (adjusted p value ≤ 0.05) in environments based on one-sided Fisher’s exact test with false discovery rate adjusted p values expressed as z-scores. c Relationship of relative abundance of the anaerobic family MCF-E with oxygen concentration and depth in samples from Saanich Inlet. Y-axis depicts depth in meters below surface, top x-axis indicates molarity of oxygen and bottom x-axis indicates relative abundance in percent of total 16S rRNA amplicons. Dark blue and light blue areas depict mean oxygen concentration and standard deviation, respectively. Gray filled points, black line, and gray area represent relative abundance in a sample, mean relative abundance, and standard deviation, respectively.