Exploring the bacterial assemblages of Acropora cervicornis in the Mexican Caribbean

Coral-associated bacterial assemblages play vital roles in the nutrition, physiology, and health of hosts. Therefore, understanding this microbiota is essential to elucidate this symbiotic relationship. The present study characterized the bacterial assemblage of Acropora cervicornis in 2 Mexican Caribbean sites and analyzed the putative metabolic functions of the dominant bacterial genera in coral tissue, as well as the surrounding seawater and sediments. The bacterial assemblages were analyzed using next-generation sequencing from the hypervariable V4 region of 16S rRNA and compared with bioinformatic analyses. The bacterial microbiota associated with A. cervicornis tissue was similar between the 2 study sites but differed from the assemblages of seawater and sediment. The genera Pseudomonas, Candidatus_Midichloria, and Acinetobater prevailed in A. cervicornis tissue. Enterobacter, Vibrio, and Synechococcus dominated in seawater, whereas Thioprofundum, Pleurocapsa, and Ilumatobacter were the most abundant in sediments. Geographical distance notwithstanding, the bacterial assemblages associated with A. cervicornis, seawater, and sediments were similar between the sampling sites, indicating spatial stability was present. In addition, the substrates differed within each site; the genera favoring the main differences among studied substrates were Pseudomonas, Synechococcus, Thioprofundum, Owenweeksia, Pleurocapsa, Candidatus_Puniceispirillum, Candidatus_Midichloria, and Rhodovibrio. The most frequently occurring metabolic functions identified in the substrates were aerobic chemoheterotrophy, sulfur respiration, and nitrogen fixation. The present study enhances our understanding of acroporid coral-associated bacteria in the Mexican Caribbean.