Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

Abstract

Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater-freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche.

Single-taxon field measurements of bacterial gene regulation controlling DMSP fate

“…16S rRNA sequencing and analysis DNA samples from ESP archived filters were used in triplicate PCR amplifications with bacterial 16S rRNA primers (Bakt_341F and Bakt_805R) over 25 cycles as per Herlemann et al, 2011 to quantify the relative abundance of Roseobacter HTCC2255 16S rRNA genes during the deployment. The primers were modified with 454 Titanium adaptors and sample-specific 5-bp barcodes.…”

Coherent dynamics and association networks among lake bacterioplankton taxa

“…The extracts contained 1-20 ng DNA per microliter. Bacterial 16S rRNA genes (Escherichia coli position 341-805) were amplified by using general bacterial primers 341F (CCTACGGGNGGCWGCAG) and 805R (GACTACHVGGGTATCTAATCC) (Herlemann et al, 2011). This primer pair matches approximately 90% of all good-quality bacterial sequences (41200 bp) and covers all phyla in the Ribosomal Database Project release 10.25.…”

Rumen prokaryotic communities of ruminants under different feeding paradigms on the Qinghai-Tibetan Plateau

“…High-throughput sequencing (HTS) technology has provided novel insights into the diversity of microbial communities [26], and by increasing sample numbers has expanded the possibilities for studying community and population dynamics over much finer temporal and spatial scales [67]. Although some studies have described the rumen microbial ecosystem under grazing and feeding regimes in cattle [24], sheep [61], cows [4,16] and yak [17] by Sanger sequencing and qPCR methods, HTS technology has not yet been used to provide comparisons concerning microbial community compositions and diversity in yaks and Tibetan sheep under different feeding paradigms.…”