Spatial and temporal investigation of the microbiome of the Caribbean octocoralErythropodium caribaeorum

The octocoral Erythropodium caribaeorum is an important species in the Caribbean coral reef community and a source of the cytotoxic natural product desmethyleleutherobin. We utilized 16S small subunit rRNA gene amplicon pyrosequencing to characterize the microbiome of E. caribaeorum collected from Florida, USA and San Salvador, The Bahamas at multiple time points. This coral was found to have a very high microbial richness with an average Chao1 estimated richness of 1464 ± 707 operational taxonomic units and average Shannon diversity index of 4.26 ± 1.65. The taxonomic class Gammaproteobacteria was a dominant member in all samples and the genus Endozoicomonas accounted for an average of 37.7% ± 30.0% of the total sequence reads. One Endozoicomonas sp. was found to be a stable member of all E. caribaeorum sequence libraries regardless of location or time of collection and accounted for 30.1% of all sequence reads. This is the first report characterizing the microbiome associated with the encrusting octocoral E. caribaeorum.