Winter mixing impacts gene expression in marine microbial populations in the Gulf of Aqaba

D. Miller, U. Pfreundt, S. Hou, S. C. Lott, W. R. Hess, I. Berman-Frank

Research output: Contribution to journalArticlepeer-review


In aquatic systems, changes in temperature and irradiance fundamentally characterize the water column and regulate microbial population structure and function. In systems with stable thermal stratification, the warm surface mixed layer is typically nutrient impoverished, limiting biological production. In periods of destratification, convective mixing of the water column exposes the microorganisms inhabiting these mixed systems to rapid variations in light availability and spectra. We explored the impact of winter deep-mixing (500 m deep mixed layer) on microbial communities from the surface (2.5 m) and the aphotic waters (440 m) in the Gulf of Aqaba by examining changes in both population composition and function via DNA and RNA sequencing. The greatest fraction of 16S sequences was assigned to Euryarchaeota, while metatranscriptomes were dominated by Synechococcus transcripts. Community composition was highly similar at both depths, yet transcription profiles differed. Phototrophic organisms found at the photic surface overexpressed genes related to catabolism and energy metabolism, while genes affiliated with biosynthesis were overexpressed at the aphotic depth. Similar transcriptional trends were ob - served in the non-photoautotrophs SAR11, Euryarchaeota, and Thaumarchaeota, with niche partitioning based on differential utilization of nitrogen and phosphorus occurring between the 2 archaeal groups. We did not detect upregulated expression of cyanobacterial genes indicative of mixotrophy or glycogen metabolism in the aphotic zone, suggesting they survive the aphotic period by utilizing photosynthates produced in the photic zone. Indications for a mixotrophic lifestyle were observed for prasinophytes, with genes related to phagocytosis overexpressed at the aphotic depth compared with the surface.

Original languageEnglish
Pages (from-to)223-242
Number of pages20
JournalAquatic Microbial Ecology
Issue number3
StatePublished - 27 Oct 2017
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgements. This work was supported by the As - semble (Association of European Marine Biological Laboratories) Infrastructure Access Call 5 to the Interuniversity Institute for Marine Sciences, Eilat, (IUI) Israel, by a BMBF-MOST joint German-Israeli research project, project number GR2378/03F0640A to I.B.-F. and W.R.H., and by the EU project MaCuMBA (Marine Microorganisms: Cultivation Methods for Improving their Biotechnological Applications; grant agreement no: 311975) to W.R.H. The financial support to S.H. by the China Scholarship Council is gratefully acknowledged. This work is in partial fulfillment of a PhD requirement for D.M., who was also supported by a Presidents’ Fellowship from Bar Ilan University. We thank the IUI logistic team and captain and crew of the RV ‘Sam Rothberg’ for help at sea and H. Elifantz for help during manuscript preparation.

Publisher Copyright:
© The authors 2017.


  • Archaea
  • Cyanobacteria
  • Deep mixing
  • Metatranscriptomics
  • Prasinophytes
  • Red Sea
  • SAR11

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


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