共同研究報告書


研究区分 開拓型研究

研究課題

 Elucidating psychrophilic algae-bacteria interaction through omics analyses
新規・継続の別 開拓型（3年目/全3年）
研究代表者／所属 北大低温研
研究代表者／職名 助教
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

 高須賀太一 北大農学研究院 助教

2

 堀千明 北大工学研究院 助教

3

 小島久弥 北大低温研 助教

研究目的 This research aims to understand the microbial community and characteristics in the snow environment by analyzing the microbial community of colored snow. Colored snow is dominated by psychrophilic algae， which are primary producers in alpine snow. Bacteria are thought to interact closely with algae， benefiting from the carbon fixed by the algae. In order to elucidate the snow microbial community and the interaction between algae and bacteria， microbial communities of colored snow will be analyzed and algae and bacteria from this environment will be isolated.
　　
研究内容・成果 colored snow with two successful sampling trips to Asahidake. In this third year， we focused our efforts on the characterization of bacteria abundant in colored snow in Antarctica， Hymenobacter nivis. Genome analysis identified the presence of genes encoding for proteins that respond to light in this bacterium， including proteorhodopsin， a tentative proton pump involved in ATP production. Proteomics analysis revealed that these proteins， including proteorhodopsin， are expressed in H. nivis. Growth curve analysis showed that light-exposed cultures grew to a higher cell density compared to dark-grown cells. The genome， proteome and physiological analysis strongly indicates that H. nivis is well-adapted to high-light environments and have a response mechanism that protects the cell and allows it to flourish under such harsh environments.
Additional growth experiments using H. nivis showed that under light conditions， the pH of the growth media decreases， suggesting that the proteorhodopsin exports protons out of the cell. Characterization of the H. nivis proteorhodopsin isolated by heterologous expression confirmed its proton pump functionality， having a maximum absorption wavelength of 530 nm and showing high activity under low temperatures. Taken together， this suggest that H. nivis is well-adapted to survive in the harsh environment of colored snow by utilizing light.
　　
成果となる論文・学会発表等 M. Terashima， K. Umezawa， et al. Microbial Community Analysis of Colored Snow from an Alpine Snowfield in Northern Japan Reveals the Prevalence of Betaproteobacteria with Snow Algae， Frontiers in Microbiology. 8:1481. Doi: 10.3389/fmicb.2017.01481， 2017.
M. Terashima， K. Ohashi， et al. Antarctic
heterotrophic bacterium Hymenobacter nivis P3T displays light-enhanced growth and expresses putative photoactive proteins， Environmental Microbiology Reports. 11(2):227-235. doi: 10.1111/1758-2229.12702， 2019.