The coral core microbiome identifies rare bacterial taxa as ubiquitous endosymbionts.

Tracy D Ainsworth,Celia Smith,Heather L Spalding,Jean-Baptise Raina,Jacqueline L Padilla-Gamiño,Erika S Woolsey,Thomas Bridge,William Leggat,Martha Zakrzewski,Ove Hoegh-Guldberg,Lutz Krause,Gergely Torda,Pim Bongaerts,Ruth D Gates,David G Bourne

doi:10.1038/ismej.2015.39

Abstract

Despite being one of the simplest metazoans, corals harbor some of the most highly diverse and abundant microbial communities. Differentiating core, symbiotic bacteria from this diverse host-associated consortium is essential for characterizing the functional contributions of bacteria but has not been possible yet. Here we characterize the coral core microbiome and demonstrate clear phylogenetic and functional divisions between the micro-scale, niche habitats within the coral host. In doing so, we discover seven distinct bacterial phylotypes that are universal to the core microbiome of coral species, separated by thousands of kilometres of oceans. The two most abundant phylotypes are co-localized specifically with the corals' endosymbiotic algae and symbiont-containing host cells. These bacterial symbioses likely facilitate the success of the dinoflagellate endosymbiosis with corals in diverse environmental regimes.

Highlights

Corals are found across a wide range of ocean habitats, from the warm sunlit tropical waters to the low light habitats of deep-water regions
The coral biosphere Bacterial DNA was isolated from the coral holobiont community, niche microhabitats of host tissues and cells that host the endosymbiotic dinoflagellate (isolated using laser capture microdissection (Figure 1))
326 055 sequence reads were obtained from A. granulosa, 403 563 sequence reads were returned from Leptoseris spp. and

Summary

Introduction

Corals are found across a wide range of ocean habitats, from the warm sunlit tropical waters to the low light habitats of deep-water regions. PE coral samples were sectioned at whole community of A. granulosa, 159 phylotypes, 7 μm, collected onto microscope slides (Menzel, representing 18 bacterial families, were identified as holobiont microbiome, 76 phylotypes identified from the symbiotic tissue microbiome and 71 phylotypes identified from endosymbiotic microbiome (Figure 1).

Results

Conclusion