The core microbiome associated with the octocorals Antillogorgia elisabethae and Erythropodium caribaeorum

Abstract

The octocorals Antillogorgia elisabethae and Erythropodium caribaeorum are common members of reef communities in the Caribbean and have been shown to contain the bioactive terpenes pseudopterosins and eleutherobin, respectively. The core microbiome of these octocorals has been identified through the use of culture dependent and culture independent bacterial libraries. For A. elisabethae this was achieved by comparing the culture independent bacterial libraries associated with the zooxanthellae and larvae, to that of the coral holobiont. For E. caribaeorum the core microbiome was identified by comparing the culture independent bacterial libraries from corals collected at various times and from various locations throughout the Caribbean. These culture independent libraries reveled that the genus Endozoicomonas is a member of the core microbiome for both octocorals. This was further confirmed through the use of fluorescent in situ hybridization. For E. caribaeorum, Endozoicomonas spp. were identified to be the dominant member of the bacterial communities regardless of time of collection or location. While they were not identified to be a dominant member of the bacterial communities associated with A. elisabethae, their presence in the larvae suggests that Endozoicomonas spp. may be transmitted vertically from parent to offspring. Knowledge of the core microbiome should prove of value in efforts to examine the role of coral-associated bacteria in natural product production.