Bacterial community transcription patterns during a marine phytoplankton bloom

Authors

  • Johanna M. Rinta-Kanto,

    1. Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
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    • Department of Food and Environmental Sciences, Division of Microbiology, University of Helsinki, PO Box 56, FIN-00014 Helsinki, Finland.

  • Shulei Sun,

    1. Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
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    • Present addresses: Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive #0446, La Jolla, CA 92093-0446, USA;

  • Shalabh Sharma,

    1. Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
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  • Ronald P. Kiene,

    1. Department of Marine Sciences, University of South Alabama, Mobile, AL 36688, USA
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  • Mary Ann Moran

    Corresponding author
    1. Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
      E-mail mmoran@uga.edu; Tel. (+1) 706 542 6481; Fax (+1) 706 542 5888.
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E-mail mmoran@uga.edu; Tel. (+1) 706 542 6481; Fax (+1) 706 542 5888.

Summary

Bacterioplankton consume a large proportion of photosynthetically fixed carbon in the ocean and control its biogeochemical fate. We used an experimental metatranscriptomics approach to compare bacterial activities that route energy and nutrients during a phytoplankton bloom compared with non-bloom conditions. mRNAs were sequenced from duplicate bloom and control microcosms 1 day after a phytoplankton biomass peak, and transcript copies per litre of seawater were calculated using an internal mRNA standard. Transcriptome analysis revealed a potential novel mechanism for enhanced efficiency during carbon-limited growth, mediated through membrane-bound pyrophosphatases [V-type H(+)-translocating; hppA]; bloom bacterioplankton participated less in this metabolic energy scavenging than non-bloom bacterioplankton, with possible implications for differences in growth yields on organic substrates. Bloom bacterioplankton transcribed more copies of genes predicted to increase cell surface adhesiveness, mediated by changes in bacterial signalling molecules related to biofilm formation and motility; these may be important in microbial aggregate formation. Bloom bacterioplankton also transcribed more copies of genes for organic acid utilization, suggesting an increased importance of this compound class in the bioreactive organic matter released during phytoplankton blooms. Transcription patterns were surprisingly faithful within a taxon regardless of treatment, suggesting that phylogeny broadly predicts the ecological roles of bacterial groups across ‘boom’ and ‘bust’ environmental backgrounds.

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