16S rRNA_metag_marine fish
The extraction of total metagenomic DNA from marine fish sample was done by using the PowerFood Microbial DNA isolation kit (MOBIO, USA). 16S rRNA was amplified using extracted total DNA and sequenced on the Illuminas MiSeq platform (Illumina, USA) at SciGenom Labs, India. After downstream processing, a total of 356,814 consensus V3 region reads were obtained which were further processed by removing chimeric sequences to give pure 354,569 reads. After singleton removal, using Uclust program (similarity cutoff = 0.97), 303 operational taxonomic units (OTUs) were generated based on sequence similarity of these pooled and clustered high-quality reads (Supplementary TableS2) (Lozupone et al.2013). Using PyNAST program, representative sequence for each OTU was identified and aligned against Greengenes core set of sequences (DeSantis et al.2006a, b). Finally, all 303 OTUs were taxonomically classified from phylum to species level using Ribosomal Database Project classifier and Greengenes OTUs database (confidence level =80%).