Psychrophilic bacteria from Spitsbergen and their role in greenhouse gas production

01 07 2026

Scientists from the Faculty of Biology, University of Warsaw, have described a new genus of Arctic bacteria, named Gelidimonas, and two new species: Gelidimonas denitrificans and Gelidimonas diazotrophica. The microorganisms were isolated from ornithogenic soil, i.e. soil formed under the influence of birds, within a little auk (Alle alle) colony on Spitsbergen. These bacteria are involved in nitrogen transformations, playing an important role both in the functioning of tundra ecosystems and in processes influencing greenhouse gas cycling.

Although polar regions are primarily associated with low temperatures and harsh living conditions, their soils harbour highly diverse microbial communities. These microorganisms play a crucial role in biogeochemical processes by participating in the cycling of elements such as carbon, nitrogen and sulphur. As climate warming progresses and permafrost thaws, microbial activity in the Arctic may increase. One consequence of these changes may be an increase in emissions of nitrous oxide, N₂O, a potent greenhouse gas produced mainly through denitrification carried out by bacteria.

Fig. 1. Arctic tundra landscape in the Hornsund region of South Spitsbergen. Photo by Julia Brzykcy.

Previous studies have shown that ornithogenic soils in the Hornsund region may constitute an important source of nitrous oxide. However, it was not clear which microorganisms were responsible for this process. To investigate this, the authors examined psychrophilic bacteria adapted to life at low temperatures and determined whether the isolated strains belonged to already known taxonomic groups or represented previously undescribed evolutionary lineages.

Fig. 2. Electron micrographs of cells of strains D2 (A, C) and D11 (B, D) grown on R2A medium at 10°C. A, B – scanning electron micrographs; scale bar: 1 μm. C, D – transmission electron micrographs showing intracellular storage granules; scale bar: 1 μm.

The two isolated strains, D2 and D11, were subjected to detailed genomic analyses. They proved to be Gram-negative, motile, psychrophilic bacteria, with an optimum growth temperature of 10°C, and were capable of denitrification. Although their 16S rRNA gene sequences were nearly identical, sharing 99.6% sequence identity, whole-genome comparative analyses showed that the strains represent two distinct species belonging to a new genus within the family Oxalobacteraceae. Strain D11 was named Gelidimonas denitrificans, whereas strain D2 was named Gelidimonas diazotrophica.

Strain D2 proved particularly interesting, as it can use hydrogen as an energy source, assimilate carbon dioxide and fix atmospheric nitrogen. Strain D11, by contrast, displays a heterotrophic lifestyle, meaning that it obtains energy from organic compounds. This demonstrates that even closely related bacteria inhabiting the same environment may perform different ecological functions. The authors emphasise that classical bacterial identification based on the 16S rRNA gene may be insufficient. Only comparisons of complete genomes make it possible to precisely determine the relationships among microorganisms and detect differences that are not visible in standard analyses.

The article “Gelidimonas denitrificans gen. nov., sp. nov., and Gelidimonas diazotrophica sp. nov. psychrophilic bacteria involved in the nitrogen cycle in tundra soils of South Spitsbergen” was published in Systematic and Applied Microbiology. The authors include students and staff members of the Faculty of Biology, University of Warsaw: Julia Brzykcy, MSc; Elvira Krakowska, MSc; Robert Stasiuk, PhD; Kamil Krakowski, MSc; Przemysław Decewicz, PhD; Alina Kiedryńska, BSc; Associate Professor Renata Matlakowska; and Professor Dariusz Bartosik, in collaboration with researchers from the Institute of Biochemistry and Biophysics of the Polish Academy of Sciences and the University of York in the United Kingdom.

Link to the publication: https://doi.org/10.1016/j.syapm.2026.126730