# Editorial: thematic issue on Polar and Alpine Microbiology

Microorganisms, representing all domains of life, have successfully colonized Earth's cold habitats. This thematic issue brings a focus on the microbial ecology of the cryobiosphere. Knowledge of biodiversity and functional roles of microorganisms inhabiting these cold environments is essential to our understanding of polar and alpine ecosystem processes in a changing climate.

The 9th International Conference on Polar and Alpine Microbiology (PAM22) took place in October 2022 in Potsdam, Germany, following a 3-year COVID driven hiatus. The decision to postpone was made in late 2020 because the strength and success of PAM meetings have always been relying on in-person interactions between participants, which are more difficult online. The meeting attracted more than 120 participants from 21 different countries, of which 41% were student participants. The science spanned nine topics that addressed a wide range of research areas from: "Microbial communities and global change" and "Microbial gene pool and biotechnology," "Eukaryotic microbial diversity" and "Adaptation, survival and subzero activity," and all the way to "Carbon and nitrogen turnover" and "Plant-microbe interactions," as well as an open session on "Cryosphere Microbiology." The 105 submitted abstracts were presented during the week-long meeting either as talks (60%), including nine keynote presentations, or as posters (40%). We placed a big emphasis on promoting early career scientists for talks and to chair sessions during the meeting. At the end of the PAM22 conference a call was issued for manuscripts to be assembled in a virtual FEMS Microbiology Ecology Thematic issue. This thematic issue on Polar and Alpine Microbiology, continuing earlier thematic issues that have focused on the microbial ecology of Earth's cryobiosphere, encompasses 30 peer-reviewed papers, with the majority being based on research presented at the PAM22 conference. We have also attracted other submissions in the field, thus broadening the scope even further.

The articles detail field studies that span all three poles with most covering microbial related research either from Arctic regions (10 papers), various mountain regions (from the Himalayas and Tibet to the US Cascades and the European Alps; 10 papers) and also Antarctica (five papers). A few papers also address comparisons between Alpine and Arctic processes or detail laboratory studies targeting adaptations or sample analyses issues (e.g. Broadwell et al. 2023).

The plethora of studies on Arctic microbial ecosystems cover aspects from the top of glaciers all the way to the marine realm. These include microbial studies related to tundra (Almela et al. 2023, Doherty et al. 2023, Michaud et al. 2023, Touchette et al. 2023), proglacial (Luláková et al. 2023, Poppeliers et al. 2022, Masumoto et al. 2023) or abruptly thawed permafrost soils (Scheel et al. 2023), to seasonal microbial reactions that control land-

ocean connectivity in tidal flats (Handler et al. 2024), and all the way to processes in coastal and open Arctic waters (Robicheau et al. 2023, von Friesen et al. 2023b) and even cover coastal thermokarst lake communities (Yang et al. 2024). Complementing these are a variety of papers that address supraglacial diversity in snow and ice habitats in Greenland, Svalbard, and Norway (Jaarsma et al. 2023, Sanchez-Cid et al. 2023, Suzuki et al. 2023) or compare Alpine and Arctic processes either addressing best practices in sequencing for snow and ice algal communities (Remias et al. 2023) or assessing how vegetation controls microbial responses to drought (Fry et al. 2023). Noteworthy, here is the Jaarsma et al. (2023) paper that was selected as one of seven FEMS Journals Article Awards for 2023 (https://fems-microbiology.org/about_fems/network-and-activities/awards/article-awards/).

Studies that address snow, ice, and soil microbial processes in mountain regions report on the controls of snow algae blooms (Hamilton and Having 2023, van Hees et al. 2023), plant-fungal symbionts (Hiesalu et al. 2023), or bacterial communities in proglacier settings (Mukhia et al. 2024) to microbial successions in chronosequences of proglacier soils and thawing permafrost soils in Tibet (Khan et al. 2023, Tang et al. 2023) and all the way to microsymbionts modulating plant characteristics in the High Atlas mountains of Morocco (Lamrabet et al. 2023) or antibiotic-producing Streptomyces in Himalayan soils (Bhat et al. 2024).

Work that highlight research results from Antarctica includes evaluations of benthic bacterial and diatom communities in lakes (Kollár et al. 2023), to fungal roles in endolithic communities (Biangioli et al. 2023) to bacterial roles in Antarctic lichens (Woltyńska et al. 2023) and naturally work in soils linked to microbial succession in proglacial soils (Vimercati et al. 2022).

The papers of this thematic issue highlight the vibrant Polar and Alpine Microbiology research community. Many of the papers invariably address issues that are of high relevance in the currently fast changing climate. It is clear that advances in sequencing and analytical opportunities allow us more and more to quantify important microbiological and microbial ecological processes that affect and are in turn affected by polar and alpine processes.

We dedicate this issue to our good friend and wonderful colleague, S. Craig Cary, who passed away in February 2024. He was a pioneering and inspiring researcher in the study of microbial life in extreme environments, including the cryobiosphere. He spent several seasons in Antarctica to study the physiology, biochemistry, and ecology of microbial communities in polar deserts. Craig was an active participant in the Polar and Alpine Microbiology Conference series, hosting the 2019 meeting at the University of Waikato—Te Whare Wānanga o Waikato, Hamilton, New Zealand (Cary et al. 2020). He will be missed by all of us.
## Author contributions

Conceptualization (LGB, DW, CL, NG-C, MMH), Writing - original draft (LB), Writing - review and editing (LGB, DW, CL, NG-C, MMH).

Conflict of interest: None declared.

## References

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Bhat AM, Hussain A, Hassan QP *et al*. Culturable *Streptomyces* spp. from high altitude, oligotrophic North Western Himalaya: a comprehensive study on the diversity, bioactivity and insights into the proteome of potential species. *FEMS Microbiol Ecol* 2024;**100**:fiae026. https://doi.org/10.1093/femsec/fiae026

Biagioli F, Coleine C, Buzzini P *et al*. Positive fungal interactions are key drivers in Antarctic endolithic microcosms at the boundaries for life sustainability. *FEMS Microbiol Ecol* 2023;**99**:fiad045. https://doi.org/10.1093/femsec/fiad045

Broadwell ELM, Pickford RE, Perkins RG *et al*. Adaptation versus plastic responses to temperature, light, and nitrate availability in cultured snow algal strains. *FEMS Microbiol Ecol* 2023;**99**:fiad088. https://doi.org/10.1093/femsec/fiad088

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Doherty SJ, Busby RR, Baker CCM *et al*. Rhizosphere microbial community structure differs between constant subzero and freeze-thaw temperature regimes in a subarctic soil. *FEMS Microbiol Ecol* 2023;**99**:fiad147. https://doi.org/10.1093/femsec/fiad147

Fry EL, Ashworth D, Allen KAJ *et al*. Vegetation type, not the legacy of warming, modifies the response of microbial functional genes and greenhouse gas fluxes to drought in Oro-Arctic and alpine regions. *FEMS Microbiol Ecol* 2023;**99**:fiad145. https://doi.org/10.1093/femsec/fiad145

Hamilton TL, Having JR. Addition of dissolved inorganic carbon stimulates snow algae primary productivity on glacially eroded carbonate bedrock in the Medicine Bow Mountains, WY, USA. *FEMS Microbiol Ecol* 2023;**99**:fiad056. https://doi.org/10.1093/femsec/fia056

Handler ER, Andersen SDJ, Gradinger R *et al*. Seasonality in land-ocean connectivity and local processes control sediment bacterial community structure and function in a High Arctic tidal flat. *FEMS Microbiol Ecol* 2024;**100**:fiad162. https://doi.org/10.1093/fems_ec/fiad162

Hiiesalu I, Schweichhart J, Angel R *et al*. Plant-symbiotic fungal diversity tracks variation in vegetation and the abiotic environment along an extended elevational gradient in the Himalayas. *FEMS Microbiol Ecol* 2023;**99**:fiad092. https://doi.org/10.1093/femsec/fia092

Jaarsma AH, Sipes K, Zervas A *et al*. Exploring microbial diversity in Greenland Ice Sheet supraglacial habitats through culturing-dependent and -independent approaches. *FEMS Microbiol Ecol* 2023;**99**:fiad119. https://doi.org/10.1093/femsec/fiad119

Khan A, Kong W, Khan S *et al*. Diversity and succession of chemolithoautotrophic microbial community along a recently deglaciation chronosequence on the Tibetan Plateau. *FEMS Microbiol Ecol* 2023;**99**:fiad066. https://doi.org/10.1093/femsec/fiad066

Kollár J, Kopalová K, Kavan J *et al*. Recently formed Antarctic lakes host less diverse benthic bacterial and diatom communities than

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Lamrabet M, Chaddad Z, Bouhnik O *et al*. Different species of *Bradyrhizobium* from symbiovars genistearum and retamae nodulate the endemic *Retama dasycarpa* in the High Atlas Mountains. *FEMS Microbiol Ecol* 2023;**99**:fiad038. https://doi.org/10.1093/femsec/fiad038

Luláková P, Šantrúčková H, Elster J *et al*. Mineral substrate quality determines the initial soil microbial development in front of the Nordenskiöldbreen, Svalbard. *FEMS Microbiol Ecol* 2023;**99**:fiad104. https://doi.org/10.1093/femsec/fiad104

Masumoto S, Mori AS, Nishizawa K *et al*. Synergistic effects of succession and microtopography of moraine on the fungal spatial diversity in a glacier forefield. *FEMS Microbiol Ecol* 2023;**99**:fiad090. https://doi.org/10.1093/femsec/fiad090

Michaud AB, Massé RO, Emerson D. Microbial iron cycling is prevalent in water-logged Alaskan Arctic tundra habitats, but sensitive to disturbance. *FEMS Microbiol Ecol* 2023;**99**:fiad013. https://doi.org/10.1093/femsec/fiad013

Mukhia S, Kumar A, Kumar R. Bacterial community distribution and functional potentials provide key insights into their role in the ecosystem functioning of a retreating Eastern Himalayan glacier. *FEMS Microbiol Ecol* 2024;**100**:fiae012. https://doi.org/10.1093/fems_ec/fiae012

Poppeliers SWM, Hefting M, Dorrepaal E *et al*. Functional microbial ecology in arctic soils: the need for a year-round perspective. *FEMS Microbiol Ecol* 2022;**98**:fiac134. https://doi.org/10.1093/fems_ec/fiac134

Remias D, Procházková L, Nedbalová L *et al*. Novel insights in cryptic diversity of snow and glacier ice algae communities combining 18S rRNA gene and ITS2 amplicon sequencing. *FEMS Microbiol Ecol* 2023;**99**:fiad134. https://doi.org/10.1093/femsec/fiad134

Robicheau BM, Tolman J, Rose S *et al*. Marine nitrogen-fixers in the Canadian Arctic Gateway are dominated by biogeographically distinct noncyanobacterial communities. *FEMS Microbiol Ecol* 2023;**99**:fiad122. https://doi.org/10.1093/femsec/fiad122

Sanchez-Cid C, Keuschnig C, Vogel TM *et al*. Impact of in situ solar irradiation on snow bacterial communities and functional potential. *FEMS Microbiol Ecol* 2023;**99**:fiad042. https://doi.org/10.1093/femsec/fiad042

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Suzuki H, Détain A, Park Y *et al*. Phylogeny and lipid profiles of snow-algae isolated from Norwegian red-snow microbiomes. *FEMS Microbiol Ecol* 2023;**99**:fiad057. https://doi.org/10.1093/femsec/fiad057

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Touchette D, Gostinčar C, Whyte LG *et al*. Lichen-associated microbial members are prevalent in the snow microbiome of a sub-arctic alpine tundra. *FEMS Microbiol Ecol* 2023;**99**:fiad151. https://doi.org/10.1093/femsec/fiad151

van Hees D, Hanneman C, Paradis S *et al*. Patchy and pink: dynamics of a *Chlainomonas* sp. (*Chlamydomonadales*, chlorophyta) algal bloom on Bagley Lake, North Cascades, WA. *FEMS Microbiol Ecol* 2023;**99**:fiad106. https://doi.org/10.1093/femsec/fiad106

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von Friesen LW, Paulsen ML, Müller O et al. Glacial meltwater and seasonality influence community composition of diatomophils in Arctic coastal and open waters. *FEMS Microbiol Ecol* 2023b;**99**:fiad067

Woltyńska A, Gawor J, Olech MA et al. Bacterial communities of Antarctic lichens explored by gDNA and cDNA 16S rRNA gene amplicon sequencing. *FEMS Microbiol Ecol* 2023;**99**:fiad015. https://doi.org/10.1093/femsec/fiad015

Yang S, Wen X, Wagner D et al. Microbial assemblages in Arctic coastal thermokarst lakes and lagoons. *FEMS Microbiol Ecol* 2024;**100**:fiae014. https://doi.org/10.1093/femsec/fiae014

Liane G. Benning

German Research Centre for Geosciences GFZ, Telegrafenberg
A71-359, 14473 Potsdam, Germany

Dirk Wagner

German Research Centre for Geosciences GFZ, Telegrafenberg
A71-359, 14473 Potsdam, Germany

Catherine Larose

Université Grenoble Alpes, CNRS, Institute of Geosciences of the Environment IGE, CS 40700, 38 058 Grenoble, France

Nina Gunde-Cimerman

University of Ljubljana, Department of Biology, Biotechnical faculty, Jamnikarjeva 101, 1000 Ljubljana, Slovenia

Max M. Häggblom

Rutgers University, Department of Biochemistry and Microbiology, 76 Lipman Drive, New Brunswick, NJ 08901-8525, United States