Niche shaping molecules of the cryosphere

• Applicants: Professor Dr. Jan Steinkühler; Jan Tebben, Ph.D.
• Subject Area: Oceanography
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562154140

Freezing seawater phase-separates in ice crystals and saline brine. Sustained microbial growth in this ecological niche requires mechanisms that cope with the low temperature, the ice/water interface, and high ionic strengths. Psychrophilic sea-ice organisms are found to produce both anti-freeze proteins and anti-freeze polysaccharides as the main secreted macromolecules which protect against the binding of ice crystals to the cell membrane. Microbial life in Antarctic sea ice, however, is not only confronted with the extreme low-temperatures and extreme salinity gradients, but very rapid seasonal transitions from one extreme to another. Our understanding of the metabolic adaptations and ability of bacteria to rapidly adjust their metabolic and enzymatic processes in response to a wide range of extreme conditions, is still lacking. This proposal aims to test the adaptation of Antarctic marine microorganisms to rapid environmental changes at the morphological, physiological, and the molecular level. We will i) structurally characterize anti-freeze macromolecular metabolites and cell membrane components of Antarctic psychrophilic bacteria and ice-algae and ii) characterize their production or degradation as a result of rapid environmental changes. The characterization of the metabolic capabilities of psychrophilic organisms is prerequisite to understand the adaptations that allow them to thrive in these extreme environments and to predict the limits of their tolerance. The overarching focus of this project will be on the structural characterization and quantification of extracellular and cell-wall associated macromolecules. We additionally seek collaborators who are interested in the intracellular response of microorganisms on the biochemical, transcriptomic and/or proteomic level.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• International Connection: France, United Kingdom
• Cooperation Partners: Professor Dr. Lois Maignien; Professor Alessandro Tagliabue, Ph.D.
• Co-Investigator: Professorin Dr. Ramona Bosse