Chlamydiae in corals: shared functional potential despite broad taxonomic diversity

Author(s)
Justin Maire, Astrid Collingro, Matthias Horn, Madeleine J H van Oppen
Abstract

Cnidarians, such as corals and sea anemones, associate with a wide range of bacteria that have essential functions, including nutrient cycling and the production of antimicrobial compounds. Within cnidarians, bacteria can colonize all microhabitats including the tissues. Among them are obligate intracellular bacteria of the phylum Chlamydiota (chlamydiae) whose impact on cnidarian hosts and holobionts, especially corals, remain unknown. Here, we conducted a meta-analysis of previously published 16S rRNA gene metabarcoding data from cnidarians (e.g., coral, jellyfish, anemones), eight metagenome-assembled genomes (MAGs) of coral-associated chlamydiae, and one MAG of jellyfish-associated chlamydiae to decipher their diversity and functional potential. While the metabarcoding dataset showed an enormous diversity of cnidarian-associated chlamydiae, six out of nine MAGs were affiliated with the Simkaniaceae family. The other three MAGs were assigned to the Parasimkaniaceae, Rhabdochlamydiaceae, and Anoxychlamydiaceae, respectively. All MAGs lacked the genes necessary for an independent existence, lacking any nucleotide or vitamin and most amino acid biosynthesis pathways. Hallmark chlamydial genes, such as a type III secretion system, nucleotide transporters, and genes for host interaction, were encoded in all MAGs. Together these observations suggest an obligate intracellular lifestyle of coral-associated chlamydiae. No unique genes were found in coral-associated chlamydiae, suggesting a lack of host specificity. Additional studies are needed to understand how chlamydiae interact with their coral host, and other microbes in coral holobionts. This first study of the diversity and functional potential of coral-associated chlamydiae improves our understanding of both the coral microbiome and the chlamydial lifestyle and host range.

Organisation(s)
Department of Microbiology and Ecosystem Science
External organisation(s)
University of Melbourne, Australian Institute of Marine Science
Journal
ISME Communications
Volume
4
No. of pages
34
ISSN
2730-6151
DOI
https://doi.org/10.1093/ismeco/ycae054
Publication date
04-2024
Peer reviewed
Yes
Austrian Fields of Science 2012
106026 Ecosystem research, 106022 Microbiology
Keywords
Portal url
https://ucrisportal.univie.ac.at/en/publications/f47a9e6f-c6c6-4d79-88dc-932236220479