16S rRNA gene PCR and amplicon deposition

The V4 hypervariable region of the 16S ribosomal RNA was amplified by PCR using the universal bacterial and archaeal primers: 515F (5′ GTGCCAGCMGCCGCGGTAA 3′) and 806R (5′ GGACTACHVGGGTWTCTAAT 3′) as used with the Earth Microbiome Project (Caporaso et al., 2012). Amplification conditions were 1 cycle of 94  °C for 3 min, 35 cycles of 94 °C for 45 s, 50 °C for 60 s, 72 °C for 90 s and a final extension of 72 °C for 10 min. The six amplicons of ∼300 bp were barcoded to allow for sample multiplexing and paired-end sequenced in the Illumina MiSeq platform at the Sequencing and Genotyping Facility of the University of Puerto Rico. The resulting demultiplexed raw sequences per sample, as well as the 803 16S rRNA gene sequence representatives of the operational taxonomic units (OTUs) per sample were deposited in the NCBI BioProject ID PRJNA379103 with SRA accession SRP102061.