> Research > Programs and projects > Theme 1 & 2

Role of cyanobacteria in present and past biogeochemical cycling
Program coordinator(s): Prof. dr. J. S. Sinninghe Damsté
Theme(s): 1 , 2
Funding date: 8-apr-05

Abstract
The fixation of N2 is the second most important biogeochemical process on Earth after photosynthetic CO2 fixation. Cyanobacteria are the only aerobic phototrophic organisms that are capable of both CO2 and N2 fixation and, therefore can be considered as key organisms in today’s biogeochemical cycles and likely also in the past. In present day oligotrophic oceans cyanobacterial N2-fixation can fuel up to half of the new production. Although the filamentous cyanobacterium Trichodesmium has been assumed to be the predominant oceanic N2-fixing microorganism, recent studies have shown that other, unicellular cyanobacteria also express N2-fixing capabilities. Although the contribution of biomass from N2-fixing cyanobacteria to the whole phytoplankton community is presently relatively small, it is unknown how important they were in the past. Unfortunately, it is difficult to trace the presence and activity of N2-fixing cyanobacteria as they do not leave readily analysable fossil remnants. However, recently we found high amounts of 2-methylhopanoids, biomarkers specific for cyanobacteria in general, deposited in sediments during so-called oceanic anoxicevents in the mid-Cretaceous. Furthermore, the bulk of organic nitrogen in these sedi ments was 15N-depleted, suggesting that N2-fixing cyanobacteria might have been the most important group of phytoplankton during the mid-Cretaceous. In light of these results, it is timely to investigate in detail the role that N2-fixing cyanobacteria play and have played in present and past biogeochemical cycles. To this end a large number of different cyanobacterial species will be cultivated under various conditions and investigated for potential biomarkers and compound-specific nitrogen and carbon isotopes. Water filtrates from different oceanic provinces will be analysed for the abundance and composition of N2-fixating cyanobacteria using geochemical and molecular biological techniques. Sediment traps and surface sediments will be analysed to investigate the transfer of biomarkers of N2-fixing cyanobacteria to the sediment. Finally, ancient sediments will be analysed to assess the relative importance of N2-fixing cyanobacteria in past ecosystems.

This program contains the following projects:
1021: Role of cyanobacteria in present day biogeochemical cycling
1022: Role of cyanobacteria in past biogeochemical cycling

Publications
Bauersachs, T., Hopmans, E.C., Compaoré, J., Stal, L.J., Schouten, S., Sinninghe Damsté, J.S. (2009). Rapid analysis of long-chain glycolipids in heterocystous cyanobacteria using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry . Rapid Communications in Mass Spectrometry23 (9): 1387-1394.
Darwin Center authors: Bauersachs T., Compaore J., Hopmans E. C., Schouten S., Sinninghe Damsté J. S., Stal L. J.

Bauersachs T., Schouten, S., Sinninghe Damsté, J.S., Kremer, B. (2009). A biomarker and δ15N study of thermally altered Silurian cyanobacterial mats. Organic Geochemistry40 (2): 149-157.
Darwin Center authors: Bauersachs T., Schouten S., Sinninghe Damsté J. S.

Bauersachs, T., Compaore, J., Hopmans, E.C., Stal, L.J., Schouten, S., Sinninghe Damsté, J.S. (2009). Distribution of heterocyst glycolipids in cyanobacteria. Phytochemistry70 (17-18): 2034-2039.
Darwin Center authors: Bauersachs T., Compaore J., Hopmans E. C., Schouten S., Sinninghe Damsté J. S., Stal L. J.

Bauersachs, T, Schouten, S., Compaore, J., Wollenzien, U., Stal, L.J., Sinninghe Damsté, J.S. (2009). Nitrogen isotopic fractionation associated with growth on dinitrogen gas and nitrate by cyanobacteria. Limnology and Oceanography54 (4): 1403-1411.
Darwin Center authors: Bauersachs T., Compaore J., Schouten S., Sinninghe Damsté J. S., Stal L. J.

Bauersachs, T. (2010). Development and application of proxies for past cyanobacterial nitrogen fixation..
Darwin Center authors: Bauersachs T.

Bauersachs, T., Speelman, E.N., Hopmans, E.C., Reichart, G.J., Schouten, S., Sinninghe Damsté, J.S. (2010). Fossilized glycolipids reveal past oceanic N2 fixation by heterocystous cyanobacteria. Proceedings of the National Academy of Sciences USA (PNAS)107: 19190-19194.
Darwin Center authors: Bauersachs T., Hopmans E. C., Reichart G. J., Schouten S., Sinninghe Damsté J. S., Speelman E. N.

Justine Compaoré and Lucas J. Stal (2010). Oxygen and the light–dark cycle of nitrogenase activity in two unicellular cyanobacteria. Environmental Microbiology12(1): 54-62.
Darwin Center authors: Compaore J., Stal L. J.

Justine Compaore (2010). O2 and temperature relations of N2 fixation in Cyanobacteria. In the daily life of Cyanobacteria.
Darwin Center authors: Compaore J.

T. BAUERSACHS, J. COMPAORE, I. SEVERIN, E. C. HOPMANS, S. SCHOUTEN, L. J. STAL AND J. S. SINNINGHE DAMSTE (2011). Diazotrophic microbial community of coastal microbial mats of the southern North Sea. Geobiology9: 349-359.
Darwin Center authors: Bauersachs T., Compaore J., Hopmans E. C., Schouten S., Sinninghe Damsté J. S., Stal L. J.