Diversity of Bacteria Associated with the Caribbean Coral Montastraea franksi

In this study we characterized the prokaryotic microbiota associated with the reef-building coral Montastraea franksi in a culture-independent manner by sequencing 16S rDNAs. The majority of the bacteria identified by this method were novel species and belonged to a wide variety of microbial groups, with cyanobacteria and α-proteobacteria being the most abundant. In contrast, the bacteria cultured from the same M. franksi samples were closely related to previously described bacteria and consisted mostly of γ-proteobacteria. These results show that the microbial diversity associated with corals can be greatly underestimated when relying exclusively on culture-based methods. Our analyses also showed that one α-proteobacteria species was present in all M. franksi samples isolated from five reefs separated by up to 10 km. This finding is suggestive of a specific microbe–coral association.