Molecular weight distribution and bacterial availability of marine dissolved organic matter

• Project/Area Number: 17K12814
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis
• Research Institution: National Institute for Environmental Studies
• Principal Investigator: Tsuchiya Kenji 国立研究開発法人国立環境研究所, 地域環境研究センター, JSPS特別研究員 (70739276)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000); Fiscal Year 2017: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 溶存態有機物 / 分子量分布 / バクテリア生産 / 分子サイズ / 分子量 / バクテリア / 脱塩 / サイズ排除クロマトグラフィー

Outline of Final Research Achievements

Using a novel method, seasonal and spatial variations of molecular weight distribution of marine dissolved organic matter (DOM) and bacterial availability of DOM were examined in Sagami Bay, Japan. The present study revealed that marine DOM had two peaks of molecular weight, around thousand and hundred thousand Da, and DOM of the lower molecular weight accounted for more than 90% of total DOM amount. Whereas, DOM of the higher molecular weight strongly correlated to bacterial growth rate, suggesting that although the higher molecular weight DOM accounted for less than 10% of the total DOM amount, the higher molecular weight DOM should be an important factor to regulate bacterial production in marine ecosystems.

Academic Significance and Societal Importance of the Research Achievements

海水には多量の塩が含まれることから，海洋DOMの分子サイズ分布の測定は技術的に困難であったが，本研究では脱塩とサイズ排除クロマトグラフィーを組み合わせた新規の測定手法を用いることにより，これまで測定されてこなかった海洋DOMの分子サイズ分布の季節・空間変動を初めて明らかにした．海洋DOMは莫大な現存量を示す上，その分子サイズは生物利用・分解性に関係することから，本研究成果は海洋の炭素循環を見積もる上で重要な知見となり得るものである．

Research Products

• [Journal Article] Seasonal variability and regulation of bacterial production in a shallow eutrophic lake (2019)
  • Author(s): Kenji Tsuchiya, Tomoharu Sano, Noriko Tomioka, Ayato Kohzu, Kazuhiro Komatsu, Ryuichiro Shinohara, Noriko Takamura, Megumi Nakagawa, Youta Sugai, VIctor S. Kuwahara, Tatsuki Toda, Hideki Fukuda, Akio Imai
  • Journal Title: Limnology and oceanography Volume: 印刷中 Issue: 6 Pages: 2441-2454
  • DOI: 10.1002/lno.11196
  • Peer Reviewed / Open Access
• [Journal Article] Seasonal variations in microbial abundance and transparent exopolymer particle concentration in the sea surface microlayer of temperate coastal waters (2018)
  • Author(s): Sugai Y、Tsuchiya K、Shimode S、Toda T
  • Journal Title: Aquatic Microbial Ecology Volume: 81 Issue: 3 Pages: 201-211
  • DOI: 10.3354/ame01869
  • Peer Reviewed
• [Presentation] 枝角類動物プランクトン2種のバクテリア生産量への影響 (2018)
  • Author(s): 土屋健司・佐野友春・冨岡典子・小松一弘・高津文人・今井章雄
  • Organizer: 2018年度日本プランクトン学会・日本ベントス学会合同大会
• [Presentation] 放射性同位体を用いない細菌生産測定法の開発と応用 (2018)
  • Author(s): 土屋健司・佐野友春・冨岡典子・高津文人・小松一弘・三浦真吾・今井章雄
  • Organizer: 日本陸水学会第83回大会
• [Presentation] 夏季沿岸域における溶存態有機物の分子量分布 (2018)
  • Author(s): 54.土屋健司・霜鳥孝一・佐野友春・冨岡典子・小松一弘・高津文人・今井章雄・佐藤貴之・菅井洋太・高山佳樹・戸田龍樹・下出信次
  • Organizer: 海洋生物シンポジウム2018