Bacterial interactions and chemical conditions in the colony microenvironment

The N2-fixing cyanobacterium Trichodesmium forms mm-sized colonies, which host not only a unique microbial community but also chemical conditions that are distinct from the water column surrounding them (i.e., microenvironments). We have used microsensors in combination with stable- and radioisotope incubations to characterize small-scale nutrient conditions and chemical and biological processes within these colony microenvironments, focusing e.g. on O2, pH and H2 microenvironments, nitrogen cycling, as well as iron dissolution and acquisition, both in laboratory cultures and in field-collected colonies. In a long-term collaboration with the team of Prof. Yeala Shaked (IUI in Eilat), we investigate the biological activity and chemical composition of Trichodesmium colonies in the Gulf of Eilat (Red Sea), with a special interest in the role of dust particles accumulated by these colonies and in the interactions of Trichodesmium with its associated bacteria.

Examples of experimental techniques used to analyse structure, composition, behaviour, and physiology of cyanobacterial colonies. We acknowledge contributions from our collaborators: N. Kessler and M. Fine (panel B), T. Neu and U. Kuhlicke (panel C), S. Basu, S. Wang, and D. de Beer (panel D), S. Myneni, N. Kessler, R. Sanders, and D. Schlesinger (panel E), A-N. Visser, F. Zhang, O. Qafoku, and R. Boiteau (panel G), A. Mijovilovich, H. Kuepper, A. Colussi, G. Konert, and O. Prášil (panel F), M. Kienhuis, R. Lopez Adams, and L. Polerecky (panel H), G. Konert (panel I). Figure modified from Eichner et al. 2023, Trends Microbiol. Panels J and K, A. Hania.

Involved at Algatech: Meri Eichner, Anxhela Hania, Ondřej Prášil

We welcome BSc or MSc students interested in the topic as well as postdocs who consider to apply for funding support. To discuss options, please contact Meri Eichner.

Related publications

Eichner M, Inomura K, Pierella-Karlusiech J, Shaked Y (2023): Better together? Lessons on sociality from Trichodesmium. Trends in Microbiology 31(10), 1072-1084.

Shaked Y, de Beer D, Wang S, Zhang F, Visser AN, Eichner M, Basu S (2023). Co-acquisition of mineral-bound iron and phosphorus by natural Trichodesmium spp. colonies Limnology and Oceanography 68(5): 1064-1077.

Wang S, Koedooder C, Zhang F, Kessler N, Eichner M, Shi D, Shaked Y (2022). Colonies of the marine cyanobacterium Trichodesmium optimize dust utilization by selective collection and retention of nutrient-rich particles. iScience. https://doi.org/10.1016/j.isci.2021.103587.

Eichner M, Wolf-Gladrow D, Ploug H (2022): Carbonate chemistry in the microenvironment within cyanobacterial aggregates under present-day and future pCO2 levels. Limnology and Oceanography 67(1): 203-218. doi: 10.1002/lno.11986.

Klawonn, I, Eichner, MJ, Wilson ST, Moradi, N, Thamdrup, B, Kümmel, S, Gehre, M, Khalili, A, Grossart, HP, Karl, DM, Ploug, H (2020): Distinct nitrogen cycling and steep chemical gradients in Trichodesmium colonies. ISME Journal 14(2): 399-412.

Eichner, M, Thoms, S, Rost, B, Mohr, W, Ahmerkamp, S, Ploug, H, Kuypers, M & de Beer, D (2019). N2 fixation in free-floating filaments of Trichodesmium is higher than in transiently suboxic microenvironments. New Phytologist 222(2): 852-863.

Eichner, M, Basu, S, Wang, S, de Beer, D, Shaked, Y (2019): Mineral iron dissolution in Trichodesmium colonies: The role of O2 and pH microenvironments. Limnology and Oceanography. https://doi.org/10.1002/lno.11377.

Eichner, M, Basu, S, Gledhill, M, de Beer, D, Shaked, Y (2019): Hydrogen Dynamics in Trichodesmium Colonies and Their Potential Role in Mineral Iron Acquisition. Frontiers in Microbiology 10, 1565.