Forschungsgruppe Biogeochemie

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Congratulations to Niels Schoffelen...
...on the successful defense of his doctoral dissertation on June 25th at the Faculty of Geosciences of the University of Bremen. His doctoral dissertation was entitled:

'Impact of phosphorus limitation on diazotrophic bloom development'

Congratulations to one of the pioneers of the Biogeochemistry Group, our technician Kirsten Imhoff...
... on her 25 year anniversary! We are looking forward to the next years.


Research in the Biogeochemistry Group focuses on microbiological and geochemical processes that control bioactive element cycling in the marine environment. We employ geochemical, microbiological, modeling, molecular and single-cell techniques to study the environmental regulation of these processes, and their effects on the global biogeochemical cycles.

Our goal is to provide fundamental insights into microbial mediated processes in the Ocean that ultimately affect Ocean chemistry, biology and climate, and vital input for models used to predict potential future changes resulting from human activities.


Recent Publications

24. October 2018

N2O production from coastal sandy sediments

In a study recently published in Environmental Microbiology (, H. Marchant and col­le­agues describe how the microbial community and highly variable conditions in sandy sediments can drive substantial emissions of the potent greenhouse gas, nitrous oxide (N2O). They reveal that different steps of denitrification appear to be carried out by distinct members of the community, in particular, the microorganisms that produce N2O, differ from the microorganisms that are consuming N2O. Therefore N2O is released into the porewater of the sediment, and a fraction of the dissolved gas is then transported into the water column and released to the atmosphere. Sandy sediments cover up to 50 % of the continental shelves and form an integral part of the land-ocean continuum, but in the past, research into the biogeochemistry and microbiology of sands has been lacking. The current paper forms part of our ongoing research into these fascinating hotspots.

H. Marchant collecting water column samples
H. Marchant collecting water column samples at the Janssand sandflat as part of the study, and the same location 7 hours later.

10. July 2018

New insights into the evolutionary history of nitrification

In a new stu­dy pu­blis­hed in the jour­nal mbio (, K. Kitzinger and col­le­agues from University of Vienna (Austria), Radboud University (The Netherlands), Aalborg University (Denmark) and the MPI for Marine Microbiology describe the first pure culture of the nitrite oxidizing genus Nitrotoga, N. fabula, its physiological and genomic potential, and reveal a novel nitrite oxidizing enzyme, which expands the picture of the evolutionary history of nitrification and hints at the possibility of archaeal nitrite oxidizers.

20. June 2018

Novel methane oxidizer from a stratified lake

A new study published in the journal Environmental Microbiology by J. GrafJ. Milucka and colleagues reports on the abundance, genomic potential and functional gene transcription of a blooming denitrifying methanotroph, "Ca. Methylomirabilis limnetica", from a deep stratified freshwater lake.


14. June 2018

The microbial nitrogen cycling network

A comprehensive review by M. Kuypers, H. Marchant and B. Kartal has been published in Nature Reviews Microbiology. This Review summarizes our current understanding of the microbial nitrogen-cycling network, including novel processes, their underlying biochemical pathways, the involved microorganisms, their environmental importance and industrial applications.

Nitrogen loss from freshwater reservoirs

A new study published in the journal Nature Communications by Dr. Wajih Naqvi (CSIR) and colleagues shows that methane accumulation in anoxic freshwater systems seems to facilitate rapid loss of reactive nitrogen. M. Kuypers and G. Lavik were involved in this work. See full MPI press release HERE.

Sulfide oxidizers in oxygen minimum zones

A new study published in the journal Nature Communications by C. Callbeck and colleagues demonstrates how offshore transport of shelf waters leads to high abundance and activity of sulfide-oxidizing denitrifying bacteria in sulfide-poor offshore OMZ waters. See full MPI press release HERE.


13. December 2017

Novel nitrogen fixer from an oxygen minimum zone

A new study published in the journal Environmental Microbiology by C. Martinez-Perez, W. Mohr and colleagues reports the isolation of a metabolically versatile non-cyanobacterial marine nitrogen fixer, Sagitulla castanea.


13. June 2017

New studies on carbon and nitrogen cycling

New studies published online with scientists from the Biogeochemistry Group:

Eichner et al. 

Chemical microenvironments and single-cell carbon and nitrogen uptake in field-collected colonies of Trichodesmium under different pCO2

Marchant et al. (see press release HERE)

Denitrifying community in coastal sediments performs aerobic and anaerobic respiration simultaneously

Oswald, Graf et al. (see press release HERE)

Crenothrix are major methane consumers in stratified lakes

Bristow et al.

Nutrients that limit growth in the ocean

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