Bacterial composition in Acropora found in  Palk Bay
Amplicons were subjected to paired-end sequencing in Illumina MiSeq platform to generate 300 bp paired-end raw reads, and then pretreated. Specific processing steps are as follows: Paired-end reads were assigned to a sample by their unique barcode, and the barcode and primer sequence were then truncated. Paired-end reads were merged using FLASH, a very fast and accurate analysis tool to merge pairs of reads when the original DNA fragments are shorter than twice of the reads length. The obtained splicing sequences were called raw tags. Quality filtering was then performed on the raw tags under specific filtering conditions of Trimmomatic v0.33 quality control process (quality score more than 30). After filtering, high-quality clean tags were obtained. The tags were compared with the reference database using UCHIME algorithm to detect chimeric sequences, and then the chimeric sequences were removed. The effective tags were obtained finally. For OTU (Operational Taxonomic Units) analysis, we used UCLUST (Edgar, 2010) in QIIME (Caporaso et al., 2010) (version 1.8.0) to cluster the tags with 97% similarity to acquire the OTUs and, then the OTUs were annotated based on Silva taxonomic database.