2013 Fiscal Year Final Research Report

The relationship between dissolved organic matter cycling and bacterioplankton in freshwater environments

Research Project

Project/Area Number	23710023
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Environmental dynamic analysis
Research Institution	Center for Environmental Science in Saitama (2012) National Institute for Environmental Studies (2011)
Principal Investigator	WATANABE Keiji 埼玉県環境科学国際センター, 水環境担当, 主任 (50575230)
Project Period (FY)	2011 – 2013
Keywords	微生物ループ / 物質循環 / 溶存有機物 / 浮遊細菌 / 湖沼環境
Research Abstract	We have succeeded to the isolation of many of dominant but unculturable freshwater bacterioplankton clusters/subclusters from the freshwater lakes and a river. These isolates were strongly dependent on the carboxylic acids as carbon source. Freshwater bacterioplankton subclusters (PnecC and PnecD) have shown the niche separation by the difference of main source of carboxylic acids in the field (photodegradation of humic substances or primary production). In addition, the production of chromophoric dissolved organic matter which has terrestrial humic-like fluorescence by part of freshwater clusters/subclusters was observed in the cultivation experiments. The contribution of freshwater bacterioplankton to carbon cycle has been partly cleared due to the cultivation-based approach using pure strains.