[A-CC32] Glaciology

[ACC32-01] Diversity and dynamics of glacier microbiome revealed by metagenomic analyses

★Invited Papers

*Takumi Murakami¹, Takahiro Segawa², Yukihiko Onuma³, Suzunosuke Usuba⁴, Shigeru Kawai⁵, Yuu Hirose⁵, Nozomu Takeuchi⁴, Yuichi Hongoh¹ (1.Institute of Science Tokyo, 2.University of Yamanashi, 3.Japan Aerospace Exploration Agency, 4.Chiba University, 5.Toyohashi University of Technology)

Keywords:Glacier ecosystem, Microbiology, Metagenomics

Glaciers and ice sheets, one of the Earth’s predominant freshwater environments, form a unique biome rich in microorganisms. Microbial activities on glacier surfaces, such as photosynthesis and inorganic nitrogen metabolism, play substantial roles in biogeochemical cycles in glaciers and downstream environments. However, details of biodiversity, functionality, and dynamics of glacier microbiota remain largely to be elucidated. To gain deeper insights into the ecosystem of microbes thriving on glaciers, we conducted metagenomic analysis, which involved sequencing and analyzing genetic information extracted from entire microbial communities.
Comparative metagenomics revealed that community structures of glacier microbiota varied significantly across the geographical regions, in particular between polar and midlatitude glaciers. For example, microbial communities in the midlatitude glaciers contained abundant bacterial species capable of denitrification, whereas such microbes were nearly absent in polar glaciers. Distribution of cyanobacterial species, key photosynthetic microorganisms, also differed between the two regions; a variety of cyanobacterial species were detected from the midlatitude glaciers, while a single dominant species prevailed in the polar glaciers.
Structural differences in microbial communities were observed not only across broad geographical regions but also within a single glacier. Our researches on an Alaskan glacier revealed that the structures of microbial communities changed along altitude. Furthermore, longitudinal analyses of the microbial samples collected from this glacier between 2001 and 2024 demonstrated the temporal shits of microbial communities, notably a recent increase in cyanobacterial abundance in the glacier’s upper area.
Our findings collectively suggest that microbes inhabiting glaciers dynamically change their distributions in response to local environmental conditions, such as nutrient availability and melting duration. Further interdisciplinary studies integrating biological, geological, and climatological data will uncover the mechanisms driving the dynamics of microbial ecosystems in glacier environments.