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ISME J. 2018 Apr;12(4):981-996. doi: 10.1038/s41396-017-0034-4. Epub 2018 Jan 15.

Benefit from decline: the primary transcriptome of Alteromonas macleodii str. Te101 during Trichodesmium demise.

Author information

1
Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany.
2
Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan, 03550, Alicante, Spain.
3
ETH Zürich, Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, Stefano-Franscini-Platz 5, CH-8093, Zürich, Switzerland.
4
Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 52900, Israel.
5
Max Planck-Genome-Centre Cologne, Carl-von-Linné-Weg 10, D-50829, Köln, Germany.
6
Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany. wolfgang.hess@biologie.uni-freiburg.de.
7
Freiburg Institute for Advanced Studies, University of Freiburg, Albertstr. 19, D-79104, Freiburg, Germany. wolfgang.hess@biologie.uni-freiburg.de.

Abstract

Interactions between co-existing microorganisms deeply affect the physiology of the involved organisms and, ultimately, the function of the ecosystem as a whole. Copiotrophic Alteromonas are marine gammaproteobacteria that thrive during the late stages of phytoplankton blooms in the marine environment and in laboratory co-cultures with cyanobacteria such as Trichodesmium. The response of this heterotroph to the sometimes rapid and transient changes in nutrient supply when the phototroph crashes is not well understood. Here, we isolated and sequenced the strain Alteromonas macleodii str. Te101 from a laboratory culture of Trichodesmium erythraeum IMS101, yielding a chromosome of 4.63 Mb and a single plasmid of 237 kb. Increasing salinities to ≥43 ppt inhibited the growth of Trichodesmium but stimulated growth of the associated Alteromonas. We characterized the transcriptomic responses of both microorganisms and identified the complement of active transcriptional start sites in Alteromonas at single-nucleotide resolution. In replicate cultures, a similar set of genes became activated in Alteromonas when growth rates of Trichodesmium declined and mortality was high. The parallel activation of fliA, rpoS and of flagellar assembly and growth-related genes indicated that Alteromonas might have increased cell motility, growth, and multiple biosynthetic activities. Genes with the highest expression in the data set were three small RNAs (Aln1a-c) that were identified as analogs of the small RNAs CsrB-C in E. coli or RsmX-Z in pathogenic bacteria. Together with the carbon storage protein A (CsrA) homolog Te101_05290, these RNAs likely control the expression of numerous genes in responding to changes in the environment.

PMID:
29335641
PMCID:
PMC5864184
DOI:
10.1038/s41396-017-0034-4
[Indexed for MEDLINE]
Free PMC Article

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