Thread by @Jennah_E_D

It’s out! Our paper “Marine Sediments Illuminate Chlamydiae Diversity and Evolution” was published in @CurrentBiology today! Below a thread with major highlights 1/11

cell.com/current-biolog…

Big thanks to fantastic co-authors! Celebrating with @DanielTamarit, @eme_laura, @cstairs, @JoranMartijn, @hfixou, Steffen Jørgensen, @anjspa1, and @Ettema_lab. Work done @MolEvoUpp, @MIB_WUR, and @uibgeo.

For a visual summary, check out our graphical abstract 2/11

In short: Phylogenetically diverse new lineages of #Chlamydiae (a bacterial phylum which includes the pathogen #Chlamydia) are abundant and active in deep #anoxic #marine #sediments taken from near Loki’s Castle #hydrothermal vent field 3/11

While exploring microbial diversity in anoxic marine sediments we identified Chlamydiae. Phylum members are obligate intracellular #symbionts of #eukaryotes, from animals to protists, and are found in oxic environments. So, what on Earth are these Chlamydiae doing there?? 4/11

We used bacterial 16S rRNA gene #amplicon sequencing and found Chlamydiae in 22 out of 30 samples, with up to 163 species-level OTUs and 43% relative abundance. These spanned and expanded known chlamydial #phylogenetic diversity. (new marine sediment chlamydiae in orange) 5/11

Using #metagenomics sequencing of four samples we reconstructed 24 Chlamydiae metagenome-assembled genomes. These form new clades across the phylum based on #phylogenetic analyses (new marine sediment chlamydiae in orange) 6/11

One group (CC-IV) is related to the pathogenic Chlamydiaceae (including the infamous Chlamydia spp.). Their common ancestor likely had #flagella and a complete TCA cycle. We also found proteins that they uniquely shared and that were likely important for their #evolution 7/11

Like chlamydiae found in microbial eukaryotes, these new groups have extended metabolic capabilities, yet resemble symbionts with: secretion systems, nucleotide transporters, incomplete amino acid/nucleotide biosynthesis, and biphasic chlamydial lifecycle proteins 8/11

Given this, we expected to find eukaryotic hosts in the marine sediments. But when we checked the metagenomes we didn’t find any that could explain the diversity and abundance of chlamydiae that we’d found 9/11

Maybe the marine sediment chlamydiae were inactive? But analyses showed that they’re actively replicating. These Chlamydiae may represent the first members of the phylum without eukaryotic hosts 10/11

Turns out that Chlamydiae are found in various different environments, and they’re often missed by 16S rRNA gene amplicon sequencing surveys. It seems there’s lots of chlamydial diversity left to be discovered! 11/11