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In order to characterize the bacterial community diversity associated to mucus of the coral Mussismilia hispida, four 16S rDNA libraries were constructed and 400 clones from each library were analyzed from two healthy colonies, one diseased colony and the surrounding water. Nine bacterial phyla were identified in healthy M. hispida, with a dominance of Proteobacteria, Actinobacteria, Acidobacteria, Lentisphaerae, and Nitrospira. The most commonly found species were related to the genera Azospirillum, Hirschia, Fabibacter, Blastochloris, Stella, Vibrio, Flavobacterium, Ochrobactrum, Terasakiella, Alkalibacter, Staphylococcus, Azospirillum, Propionibacterium, Arcobacter, and Paenibacillus. In contrast, diseased M. hispida had a predominance of one single species of Bacteroidetes, corresponding to more than 70% of the sequences. Rarefaction curves using evolutionary distance of 1% showed a greater decrease in bacterial diversity in the diseased M. hispida, with a reduction of almost 85% in OTUs in comparison to healthy colonies. integral-Libshuff analyses show that significant p values obtained were <0.0001, demonstrating that the four libraries are significantly different. Furthermore, the sympatric corals M. hispida and Mussismilia braziliensis appear to have different bacterial community compositions according to Principal Component Analysis and Lineage-specific Analysis. Moreover, lineages that contribute to those differences were identified as alpha-Proteobacteria, Bacteroidetes, and Firmicutes. The results obtained in this study suggest host-microbe co-evolution in Mussismilia, and it was the first study on the diversity of the microbiota of the endemic and endangered of extinction Brazilian coral M. hispida from Abrolhos bank.

Aims: We performed the first characterization of the microbiota associated with the reef coral Mussismilia braziliensis by means of a culture-independent approach., Methods and Results: The main groups were Proteobacteria, Cyanobacteria and unclassified bacteria according to the 16S rDNA libraries. Most of the sequences of the mucus of healthy and diseased M. braziliensis did not find close matches in GenBank (i.e. >97% 16S rDNA similarity). Most of the sequences of seawater and mucus of healthy coral fell into tight clusters (17 and 15 clusters respectively). In contrast, most of the sequences of mucus of diseased coral did not form clusters. The rarefaction curves indicate saturation in the recovery of higher taxa (approximately 40 phyla). However, the number of species in the coral mucus (n = 130-170) and seawater (n = 170) did not reach a plateau., Conclusions: The coral microbiota encompasses several potentially novel species and higher taxa. The microbiota of M. braziliensis appears to be species-specific. Diseased coral may have provided a suitable place for colonization by opportunistic bacteria, resulting in a greater bacterial diversity., Significance and Impact of the Study: The first study on the diversity of the microbiota of the endemic and endangered of extinction coral M. braziliensis.