Worldwide exploration of the microbiome harbored by the cnidarian model, Exaiptasia pallida (Agassiz in Verrill, 1864) indicates a lack of bacterial association specificity at a lower taxonomic rank

• Published in: PeerJ (San Francisco, CA) Vol. 5; p. e3235
• Main Authors: Brown, Tanya, Otero, Christopher, Grajales, Alejandro, Rodriguez, Estefania, Rodriguez-Lanetty, Mauricio
• Format: Journal Article
• Language: English
• Published: United States PeerJ. Ltd 16-05-2017; PeerJ, Inc; PeerJ Inc
• Subjects: Abundance; Algae; Aquatic microorganisms; Bacteria; Bacteroides; Biology; Captivity; Cnidaria; Coevolution; Community structure; Consortia; Coral; Coral reefs; Deoxyribonucleic acid; DNA; Ecology; Environmental research; Evolution; Exaiptasia pallida; Genetic aspects; Host specificity; Host-microbe interaction; Introduced species; Laboratories; Marine Biology; Metazoans; Microbiology; Microbiome; Museums; Natural history; Oceans; Physiology; Population; Proteobacteria; Ribosomal DNA; rRNA 16S; Sea anemone; Symbiodinium; Symbionts; Symbiosis; Symbiosis; Host-microbe interaction; Coral; Cnidaria; Sea anemone; Microbiome
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.3235

Examination of host-microbe interactions in early diverging metazoans, such as cnidarians, is of great interest from an evolutionary perspective to understand how host-microbial consortia have evolved. To address this problem, we analyzed whether the bacterial community associated with the cosmopolitan and model sea anemone
shows specific patterns across worldwide populations ranging from the Caribbean Sea, and the Atlantic and Pacific oceans. By comparing sequences of the V1-V3 hypervariable regions of the bacterial 16S rRNA gene, we revealed that anemones host a complex and diverse microbial community. When examined at the phylum level, bacterial diversity and abundance associated with
are broadly conserved across geographic space with samples, containing largely
and
However, the species-level makeup within these phyla differs drastically across space suggesting a high-level core microbiome with local adaptation of the constituents. Indeed, no bacterial OTU was ubiquitously found in all anemones samples. We also revealed changes in the microbial community structure after rearing anemone specimens in captivity within a period of four months. Furthermore, the variation in bacterial community assemblages across geographical locations did not correlate with the composition of microalgal
symbionts. Our findings contrast with the postulation that cnidarian hosts might actively select and maintain species-specific microbial communities that could have resulted from an intimate co-evolution process. The fact that
is likely an introduced species in most sampled localities suggests that this microbial turnover is a relatively rapid process. Our findings suggest that environmental settings, not host specificity, seem to dictate bacterial community structure associated with this sea anemone. More than maintaining a specific composition of bacterial species some cnidarians associate with a wide range of bacterial species as long as they provide the same physiological benefits towards the maintenance of a healthy host. The examination of the previously uncharacterized bacterial community associated with the cnidarian sea anemone model
is the first global-scale study of its kind.