16S rRNA-Seq of seawater
For each DNA sample, the V4 hypervariable region of the bacterial 16S rRNA gene was amplifified using the universal primers 515F (5-GTGCCAGCMGCCGCGGTAA-3) and 806R (5-GGACTACHVGGGTWTCTAAT-3). After amplification, the PCR products were purified using Agencourt AMPure XP magnetic beads with DNA finally dissolved in the Elution Buffer.