ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Extreme Microbiology
This article is part of the Research TopicPsychrotolerant Microbes: Ecological Adaptations and Biotechnological PotentialView all 4 articles
Environmental distribution, physiology and genomic adaptations of arctic ammonia-oxidizing archaea
Provisionally accepted
- University of Vienna, Vienna, Austria
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Ammonia oxidizing archaea (AOA) are the main drivers of nitrification in arctic soils, which are strongly affected by warming temperatures due to climate change, accelerating permafrost thawing and potentially leading to the release of stored nitrogen from the soil in the form of the potent greenhouse gas nitrous oxide (N2O). Compared to other terrestrial environments, the diversity of AOA in arctic soils was reported to be very low, with only two specific clades detected in most arctic ecosystems. However, to date no ammonia oxidizing model organism was available in pure culture to study the effect of climate change on the arctic nitrifier communities. In this study we link 16S rRNA with amoA taxonomies to expand earlier studies on the diversity of AOA in arctic soils with samples covering half of the circumpolar region, and we present the first pure culture and closed genome of a psychrotolerant AOA strain, Candidatus Nitrosocosmicus arcticus Kfb, paving the way for a deeper understanding of nitrification in arctic ecosystems. The dominance of AOA clades NS-zeta and NS-gamma was corroborated, while a third, non-ammonia oxidizing clade of Nitrososphaerales was also found to dominate certain sites with implications for carbon cycling. All clades showed distinct distribution patterns and were found to be influenced differently by soil physicochemical parameters such as pH, water content and organic carbon content. After 15 years of continuous cultivation, Ca. Nitrosocosmicus arcticus was isolated in pure culture and shown to actively oxidize ammonia at 4°C, the lowest reported temperature so far, expanding the temperature range of reported ammonia oxidation from 4°C to 74°C. At temperatures above 20°C, which represents a plausible scenario in the arctic during heat waves, ammonia oxidation from this strain proved to be unstable over prolonged periods of time.
Keywords: Nitrification, ammonia-oxidizing archaea, Arctic, Nitrous Oxide, Climate Change
Received: 10 Oct 2025; Accepted: 28 Nov 2025.
Copyright: © 2025 Montserrat Díez, Dreer, Schleper and Kerou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Melina Kerou
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