In this study, the bacterial microbiota associated with apparently healthy corals of Acropora palmata, Orbicella faveolata, and Porites porites and the surrounding seawater and sediment were evalu ated via the MiSeq Illumina sequencing of the V4 region of 16S rRNA at three reef sites in the Mexican Caribbean. Bacterial assemblages associated with apparently healthy corals and sediments showed no significant differences between sites. The colonies of A. palmata showed a dominance of families Amoebophilaceae, Spirochaetaceae, Myxococcaceae, and Cyclobacteriaceae. Meanwhile, the colonies of O. faveolata and P. porites revealed a high prevalence of the Rhodobacteraceae and Kiloniellaceae families. The families Rhodobacteraceae, Cryomorphaceae, Cyanobiaceae, and Flavobacteriaceae were predominant in seawater samples, while Pirellulaceae, Nitrosococcaceae, and Woeseiaceae were predominant in sediments. Variations in A. palmata bacterial assemblages were correlated with salinity, sea surface temperature, and depth. These variables, along with nitrate, phosphate, and ammonium concentrations, were also correlated with changes in the bacterial composition of P. porites, seawater, and sediments. However, none of the environmental variables were related to the bacterial taxa of O. faveolata. Aerobic chemoheterotrophy and fermentation, followed by nitrate reduction and ureolysis, were the metabolic functions with the highest occurrence in the bacterial assemblages associated with all substrates.