Marine Molecular Microbiology

The research interests of the group concern marine microbial ecology. We apply molecular and microbiological tools to identify factors that regulate bacterioplankton community composition in the ocean. Recent and ongoing projects are especially related to the ecology of heterotrophic N2-fixing bacterioplankton and bacterial diversity and population dynamics.

In parallel with the microbiology projects, we apply molecular tools in projects adressing aspects of plankton ecology. 

Standard microbiology techniques and bacterial cultivation are combined with state-of-the-art molecular methodology such as: PCR, Real-Time PCR, metagenomics, transcriptomics and amplicon sequencing. Approaches include field work as well as experimental work.


























The Riemann group, June 2021. Front, from left: Stine Zander Hagen, Lasse Riemann, Vasiliki Papazachariou, Weronika Kolodziejczyk, Maya Dodhia. Back, from left: Søren Hallstrøm, Lisa von Friesen, Víctor Fernández Juárez, Dan J. Kristensen
Meriel, Ellen and Pernille were not present at this summerparty.


Name Title Phone E-mail
Lasse Riemann Professor +4535321959 E-mail
Lisa Winberg von Friesen PhD Fellow +4535332787 E-mail
Meriel Jennifer Bittner PhD Fellow +4535333744 E-mail
Søren Hallstrøm Postdoc +4535331089 E-mail
Vasiliki Papazachariou PhD Fellow +4535321675 E-mail
Victor Fernandez Juarez Postdoc +4535320317 E-mail

Other members

Name Title
Ellen Salamon Master student
Stine Hagen Zander Master student
Pernille Fornitz Marloth Master student


Professor Lasse Riemann
Professor in Marine molecular microbiology

Marine Biological Section
Strandpromenaden 5
DK-3000 Helsingør, Denmark

Researcher ID
Phone: +45 35 32 19 59

Specialty Chief Editor in Frontiers in Microbiology


13 December 2021. New paper available online in Limnology and Oceanography: Hallstrøm S, Benavides M, , Salamon E, Evans CW, Potts LJ, Granger J, Tobias CR, Moisander PH, Riemann L. Pelagic N2 fixation dominated by sediment diazotrophic               communities in a shallow temperate estuary

1 December 2021. New paper in press in Biogeosciences: Ridame C, Dinasquet J, Hallstrøm S, Bigeard E, Riemann L, Van Wambeke F, Bressac M, Pulido-Villena E, Taillandier V, Gazeau F, Tover-Sanchez A, Baudoux A-C, Guieu C. Nfixation in the Mediterranean Sea related to the composition of the diazotrophic community, and impact of dust under present and future environmental conditions

27 July 2021. Congrats to Subhendu. Our paper was now chosen for the Editors' highlights page in Nature Communications.

17 July 2021. Lisa is soon leaving on a 2 month cruise to the North Pole. See press release

2. July 2021. Congrats to Subhendu with our new paper in Nature Communications on particle-associated N2 fixation. See also our press release.

May 2021. Welcome to postdoc Víctor Fernández Juárez and PhD student Vasiliki Papazachariou in our group.

Congratulations to Søren Hallstrøm with his successful PhD defense 29 January.

January 2021. 2-year Postdoc position available on marine bacterial community composition with special emphasis on pathogenic Vibrios.
Deadline for application is 17. February; tentative start 1. April 2021.

January 2021. 3-year PhD position available on marine nitrogen fixation
Deadline for application 2. February; tentative start 1. April 2021.

Nov. 2020, Lisa's mini-review on Arctic nitrogen fixation is now published: von Friesen, L.W, Riemann, L. Nitrogen fixation in a changing Arctic Ocean: An overlooked source of nitrogen? Frontiers in Microbiology, 11: 596426

Nov. 2020: New DFF-project funded: Future stimulated nitrogen fixation: threatening the health of coastal ecosystems?”. PI of this four-year EU project fundet by Independent Research Fund, Denmark. From spring 2021, a three-year PhD position will become available in our group. 

Oct 2020: New EU-project funded: Pathogenic Vibrio bacteria in the current and future Baltic Sea waters: mitigating the problem (BaltVib)”. Partner in this three-year EU project fundet by the Biodiversa program. A two-year postdoc postion will become available in our group, starting in spring 2021. 

Saulia, E., Benavides, M., Henke, B.A, Turk-Kubo, K.A, Cooperguard, H., Grosso, O., Desnues A., Rodier, M., Dupouy, C., Riemann, L., Bonnet, S.Seasonal shifts in diazotroph players: patterns observed over a two-year time series in the New Caledonian lagoon (Western Tropical South Pacific Ocean). Frontiers in Marine Science

Benavides M, Duhamel S, Van Wambeke F, Shoemaker KM, Moisander PH, Salamon E, Riemann L, Bonnet S. Dissolved organic matter stimulates N
2 fixation and nifH gene expression in natural Trichodesmium colonies. 2020. FEMS Microbiol Letters 367, fnaa034