Quantification of bacterial production in rivers: river water and biofilm on stones in river beds

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K12140
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• 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, 地域環境保全領域, 研究員 (70739276)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 河川 / バクテリア / バイオフィルム / 瀬淵構造 / 流速 / 一般線形モデル / 溶存態有機物 / 安定同位体

Outline of Final Research Achievements

This study investigated the dynamics of bacterial production in river water and biofilms formed on stones in the river bed. It was found that river water bacteria and biofilm bacteria share a common regulator, water temperature, and that there are different regulators for each. River water bacteria showed a relationship with river water quality, such as nutrients and organic matter, but not with river structure, such as riffles and pools. On the other hand, biofilm bacteria showed no significant relationship with river water quality, but depended on river structures such as riffles and pools. This suggests that the physical environment, such as the flow velocity, affected the rate of substrate supply to the biofilm and the biofilm formation process, thereby controlling the production dynamics.

Free Research Field

陸水学

Academic Significance and Societal Importance of the Research Achievements

バクテリア生産の測定には放射性同位体を使用する手法が一般的である．放射性同位体を使用しなければならない測定法ゆえに，屋外での使用に強い制限や，サンプルの取り扱いが非常に困難であり，河川のバイオフィルムの生産動態の実測例は非常に限られていた．本研究では放射性同位体を用いない新規手法を適用し，これまで知見が限られていた河川におけるバイオフィルムバクテリア生産動態及び制御要因を明らかにし，水圏における物質循環の理解を貢献する知見を提供した．