Coral samples were collected from six survey sites in the Gulf of Thailand (Mannai, Tao, Talu) and the Andaman Sea (Maiton, Similan, Tachai). Porites lutea is one of the dominant reef-builders in the Indo-Pacific. Very little is known about the composition and structure of bacterial communities associated with P. lutea reefs. The purpose of this study is twofold: 1) to demonstrate the advantages of using PacBio circular consensus sequencing technology in microbial community studies and 2) to investigate the diversity and structure of P. lutea-associated bacterial communities. This is the first metagenomic study of marine environmental samples that utilises the PacBio sequencing system to capture full-length 16S rRNA sequences. We observed geographically distinct coral-associated microbial profiles between samples from the Gulf of Thailand and Andaman Sea. We also examined the core conserved microbiome harboured by P. lutea and identified a group of bacteria that were consistently present across diverse reef habitats. Finally, we demonstrated the superior performance of full-length 16S rRNA sequences in resolving taxonomic uncertainty at the species level.?