Single cell analysis of bacterial growth in aquatic environment

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K12308
• 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: Kyoto University
• Principal Investigator: Kusakabe Taketoshi 京都大学, 工学研究科, 助教 (40462585)
• Co-Investigator(Kenkyū-buntansha): 清水 芳久 京都大学, 工学研究科, 教授 (20226260)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 琵琶湖 / 細菌群集 / 増殖解析 / シングルセル解析 / 難分解性有機物

Outline of Final Research Achievements

The recalcitrant dissolved organic matter that is difficult for bacterioplancton to decompose in lakes is increasing in Japan since mid 1980's. We hypothesized that a bacterial community, which occupies an important position in the microbial food web, produces recalcitrant dissolved organic matter in Lake Biwa. In this research, We developed single-cell analysis method of bacterial growth that does not require DNA denaturation treatment and can be combined with other methods, and analyzed the bacterial growth characteristics of each bacterial cell using EdU. As a result, the annual bacterial production in Lake Biwa was estimated to be 81 ug/L/year. The amount of carbon flowing to bacterial production can be estimated to be less than 1% of the primary production in both summer and winter, and it is clear that, on annual average, the microbial loop in Lake Biwa is not the major path in the carbon cycle.

Free Research Field

水環境、廃棄物・資源循環

Academic Significance and Societal Importance of the Research Achievements

琵琶湖では、微生物に分解されにくい難分解性有機物の増加が指摘されてきた。本研究では、微生物食物網で重要な位置を占める細菌群集が、難分解性有機物を産生していると考え、琵琶湖の物質循環に果たす細菌群集の役割を調べた。その結果、細菌二次生産へ流れる炭素量は一次生産量の1%程度と見積もられ、平均的に見ると琵琶湖における炭素循環において微生物ループは主要な経路ではないことが明らかとなった。しかしながら、細菌二次生産が活発に行われているホットスポットの存在や、細菌二次生産が炭素制限を受けていることを示唆する結果は学術的に意義があり、将来における湖沼の有機物管理にも資する研究成果であると言える。