Impact of a phytoplankton bloom on the diversity of the active bacterial community in the southern North Sea as revealed by metatranscriptomic approaches

Authors

  • Bernd Wemheuer,

    1. Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
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  • Simon Güllert,

    1. Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
    Current affiliation:
    1. Microbiology and Biotechnology, Biocenter Klein Flottbek, Hamburg, Germany
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  • Sara Billerbeck,

    1. Biology of Geological Processes – Aquatic Microbial Ecology, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Oldenburg, Germany
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  • Helge-Ansgar Giebel,

    1. Biology of Geological Processes – Aquatic Microbial Ecology, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Oldenburg, Germany
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  • Sonja Voget,

    1. Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
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  • Meinhard Simon,

    1. Biology of Geological Processes – Aquatic Microbial Ecology, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Oldenburg, Germany
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  • Rolf Daniel

    Corresponding author
    1. Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
    • Correspondence: Rolf Daniel, Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University Göttingen, Grisebachstr. 8, D-37077 Göttingen, Germany. Tel.: 0049 551 393827; fax: 0049 551 3912181; e-mail: rdaniel@gwdg.de

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Abstract

Despite their importance for ecosystem functioning, little is known about the composition of active marine bacterioplankton communities. Hence, this study was focused on assessing the diversity of these communities in the southern North Sea and examining the impact of a phytoplankton spring bloom on the ambient bacterioplankton community. Community composition in and outside the bloom was assessed in 14 samples by pyrosequencing-based analysis of 16S rRNA gene amplicons generated from environmental RNA. The data set comprised of 211 769 16S rRNA gene sequences. Proteobacteria were the predominant phylogenetic group with Alphaproteobacteria and Gammaproteobacteria as the most abundant classes. Actinobacteria and Bacteroidetes were identified in minor abundances. Active bacterial communities were dominated by few lineages such as the Roseobacter RCA cluster and the SAR92 clade. Community structures of three selected samples were also assessed by direct sequencing of cDNA generated from rRNA-depleted environmental RNA. Generated data sets comprised of 988 202 sequences. Taxonomic assignment of the reads confirmed the predominance of Proteobacteria. The examined phytoplankton spring bloom affected the bacterioplankton community structures significantly. Bacterial richness was reduced in the bloom area, and the abundance of certain bacterial groups was affected by bloom presence. The SAR92 clade and the Roseobacter RCA cluster were significantly more abundant and active in the bloom. Functions affected by the bloom include photosynthesis, protein metabolism, and DNA metabolism.

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