Microbial communities play central roles in ecosystem functioning. Microbes are also known to be critical for coral nutrition, homeostasis and protection against diseases. Shifts in population composition of coral-associated microorganisms often correlate with the onset of diseases and coral-bleaching, confirming their role in coral health and, therefore, the stability of reef ecosystems. Characterizing microorganisms and their ecological niches is important in clarifying their roles and the environmental conditions they respond to. This understanding is especially critical currently in the face of increasing climatic and human-related threats on marine ecosystems leading to a significant loss in biodiversity and ecosystem function. This preliminary report previews the first description of coastal Western Indian Ocean microorganisms identified by sequencing 16S rRNA gene from seawater and sediment samples. These samples were used for the optimization of microbial DNA isolation for a metagenomic study aimed at profiling the coral reef microbiome of the same region.