共同研究報告書


研究区分 開拓型研究

研究課題

 気候変動下における彩雪現象の解明
新規・継続の別 開拓型（3年目/全3年）
研究代表者／所属 ベルリン応用科学大
研究代表者／職名 教授
研究代表者／氏名 寺島美亜

研究分担者／氏名／所属／職名
　
氏　　名
所　　属
職　　名

1

 Jackson Tsuji JAMSTEC 博士研究員

2

 梅澤和寛 静岡県立大 助教

3

 Rudolf Amann マックスプランク海洋微生物学研究所 教授

4

 福井学 北大低温研

5

 田中亮一 北大低温研

6

 渡邉友浩 北大低温研

研究目的 Colored snow formed by microbial activity in alpine and polar regions is well documented and ecologically important， yet the mechanisms behind its formation remain poorly understood. Understanding microbial interactions is crucial， particularly in the context of climate change. This study examines the composition of microbial communities in colored snow， isolates previously uncharacterized microorganisms for physiological analysis， and uses metagenomics to identify key metabolic pathways operating in these systems.
　　
研究内容・成果 We collected high-quality green-colored snow samples containing abundant algal biomass from Langhovde， Antarctica. Microscopic observations confirmed the presence of numerous microalgal cells responsible for the green pigmentation. These samples were subjected to comprehensive community and genomic analyses， including 18S rRNA and 16S rRNA amplicon sequencing， metagenomic assembly， and microbial strain isolation.
Amplicon sequencing revealed that green algae dominated the eukaryotic community， with the majority of taxa belonging to the class Chlorophyceae， followed by Trebouxiophyceae. In addition to green algae， fungal taxa affiliated with the division Basidiomycota and the flagellate genus Heteromita were detected. Analysis of the prokaryotic community showed that Bacteroidia was the most abundant class， with Gammaproteobacteria and Alphaproteobacteria also well represented.
Metagenomic analysis resulted in the recovery of 30 prokaryotic metagenome-assembled genomes (MAGs)， among which Gammaproteobacteria within the family Burkholderiaceae were particularly abundant. A prokaryotic gene catalog was further constructed， representing approximately 10% of the total metagenomic data. Functional annotation of the most abundant genes revealed a strong enrichment of genes associated with photosynthesis， photoreception， and DNA damage response. Notably， multiple rhodopsin and rhodopsin-like genes were identified， suggesting that light-driven energy acquisition and light sensing are important adaptive strategies in this environment. Together， these findings indicate that microorganisms inhabiting colored snow actively exploit light while simultaneously mitigating the harmful effects of intense solar radiation at the snow surface.
To further characterize key bacterial members of the community， numerous bacterial strains were successfully isolated from the snow samples and identified using 16S rRNA gene sequencing with Nanopore technology. Among these isolates， two strains are of particular interest， as they likely represent previously undescribed bacterial species.
　　
成果となる論文・学会発表等 Kondo， K.， Ohtake， R.， Nakano， S.， Terashima， M.， Kojima， H.， Fukui， M.， Demura， M.， Kikukawa， T.， and Tsukamoto， T. (2024) Contribution of Proteorhodopsin to Light-Dependent Biological Responses in Hymenobacter nivis P3T Isolated from Red Snow in Antarctica. Biochemistry， 63(18): 2257–2265.

Terashima， M. Unlocking the mysteries of snow algae and its associated cryophilic bacteria: An untapped bioresource? Presentation at Hokkaido-Bremen-Exchange-Day， New Frontiers in Environmental Science section， 2024.12.11.