Diversity of particle-attached bacteria in the Baltic Sea

To evaluate if changes in salinity affecting diversity of particle-associated (PA) and free-living (FL) bacteria, we sampled both bacterial fractions in two seasons (summer and fall/winter) in surface waters of three selected stations of the Baltic Sea representing marine, mesohaline and oligohaline environments. All samples were PCR amplified with 30 cycles using the primer pair Bakt_341F (CCTACGGGNGGCWGCAG) and Bakt_805R (ACHVGGGTATCTAATCC). Primers were tailed with sample-specific 5 bp barcodes a 454-adptor region, spanning variable regions V3 and V4 of the 16S rRNA gene. PCR products were purified with Agencourt AMPure XP magnetic beads (Beckman Coulter GmbH, Krefeld, Germany), quantified with a Picogreen assay (LifeTechnologies, Carlsbad, USA), diluted and equally pooled. The bidirectional sequencing was performed on a 454 platform with Titanium Flex chemistry (Roche etc.).