Localization of bacterial symbionts in the holobiont of the precious coral Corallium rubrum

Corals engage in symbioses with micro-organisms that provide nutrients and protect the host. Where the prokaryotic microbes perform their symbiotic functions within a coral is, however, poorly understood. Here, we studied the tissue-specific microbiota of the precious coral Corallium rubrum by dissecting its tissues from the skeleton and separating the white polyps from the red-colored coenenchyme, followed by 16S rRNA gene metabarcoding of the three fractions. Dissection was facilitated by incubating coral fragments in RNAlater, which causes tissues to detach from the skeleton.