EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Metagenomes reveal purple non-sulfur bacteria linked to bare ice habitats on the Greenland Ice Sheet

Christoph Keuschnig1, Christopher B. Trivedi1, Helen Feord1, Rey Mourot1,2, Athanasios Zervas3, Marie Bolander3, Katie Sipes3, Laura Perini3, Martyn Tranter3, Alexandre M. Anesio3, and Liane G. Benning1,2
Christoph Keuschnig et al.
  • 1GFZ German Research Centre for Geosciences, Interface Geochemistry, Potsdam, Germany (
  • 2Free University of Berlin, 12249 Berlin, Germany
  • 3Aarhus University, Department of Environmental Science, DK-4000 Roskilde, Denmark

Phototrophic organisms blooming during the summer melt season on snow and ice surfaces are dominated by eukaryotic green algae (Chlorophytes and Streptophytes, respectively), with Cyanobacteria restricted to cryoconite habitats. However, the role and interactions between the algae and other light-harvesting organisms are largely understudied in these ecosystems.

We searched metagenomes of snow and ice samples collected from the Greenland Ice Sheet during the summer melting season for signatures indicating anoxygenic photosystems, which are used by certain groups of bacteria to gain energy from light without releasing oxygen. Two metagenome assembled genomes (MAGs) carrying all genes necessary to perform anoxygenic photosynthesis and carbon-fixation were found. Whole-genome phylogenetic comparison placed the MAGs within the Alpha- and Gamma-proteobacteria, which was confirmed by alignment of the respective functional marker genes pufL and pufM to known sequences from cultured anoxygenic phototrophic bacteria. The identified functions and phylogeny suggest that the MAGs belong within the group of purple non-sulfur bacteria, a pigmented and metabolically versatile group of bacteria often found in shallow aqueous environments, but very little is documented in cryogenic environments. Our data show that these procaryotic organisms are preferably linked to glacial ice algae habitats and, to a lesser extent, to algae in snow habitats. Our results pose intriguing ecological questions for supraglacial habitats, such as the contribution of these procaryotes to the ongoing biological darkening of ice surfaces or the potential mutualistic light-harvesting strategies on ice, as the used wavelength of purple non-sulfur bacteria are complementary to those used by indigenous high abundant glacial ice algae.

How to cite: Keuschnig, C., Trivedi, C. B., Feord, H., Mourot, R., Zervas, A., Bolander, M., Sipes, K., Perini, L., Tranter, M., Anesio, A. M., and Benning, L. G.: Metagenomes reveal purple non-sulfur bacteria linked to bare ice habitats on the Greenland Ice Sheet, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11774,, 2023.