Open AccessThe Native Bacterioplankton Community in the Central Baltic Sea Is Influenced by Freshwater Bacterial Species
Author(s) -
Lasse Riemann,
Cecilia Leitet,
Thomas Pommier,
Karin Simu,
Karin Holmfeldt,
Ulf Larsson,
Åke Hagström
Publication year - 2008
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.01983-07
Subject(s) - bacterioplankton , brackish water , biology , temperature gradient gel electrophoresis , ecology , phylotype , bacteroidetes , picoplankton , verrucomicrobia , microbial population biology , betaproteobacteria , seawater , actinobacteria , salinity , nutrient , 16s ribosomal rna , phytoplankton , bacteria , genetics
The Baltic Sea is one of the largest brackish environments on Earth. Despite extensive knowledge about food web interactions and pelagic ecosystem functioning, information about the bacterial community composition in the Baltic Sea is scarce. We hypothesized that due to the eutrophic low-salinity environment and the long water residence time (>5 years), the bacterioplankton community from the Baltic proper shows a native “brackish” composition influenced by both freshwater and marine phylotypes. The bacterial community composition in surface water (3-m depth) was examined at a single station throughout a full year. Denaturing gradient gel electrophoresis (DGGE) showed that the community composition changed over the year. Further, it indicated that at the four extensive samplings (16S rRNA gene clone libraries and bacterial isolates from low- and high-nutrient agar plates and seawater cultures), different bacterial assemblages associated with different environmental conditions were present. Overall, the sequencing of 26 DGGE bands, 160 clones, 209 plate isolates, and 9 dilution culture isolates showed that the bacterial assemblage in surface waters of the central Baltic Sea was dominated byBacteroidetes but exhibited a pronounced influence of typical freshwater phylogenetic groups withinActinobacteria ,Verrucomicrobia , andBetaproteobacteria and a lack of typical marine taxa. This first comprehensive analysis of bacterial community composition in the central Baltic Sea points to the existence of an autochthonous estuarine community uniquely adapted to the environmental conditions prevailing in this brackish environment.