Development of in situ measurement system for growth and metabolic activity of microbial community in deep ocean

Research Project

Project/Area Number	16K12576
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Environmental dynamic analysis
Research Institution	University of Tsukuba
Principal Investigator	UTSUMI MOTOO 筑波大学, 生命環境系, 准教授 (60323250)
Research Collaborator	AMANO chie (SATO chie)
Project Period (FY)	2016-04-01 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000) Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000) Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Keywords	生物海洋 / 微生物群集生産 / 物質循環 / 海洋中・深層 / 微生物の増殖と代謝 / 微生物代謝 / 海洋中深層
Outline of Final Research Achievements	Prokaryotic heterotrophic production is a key process in the ocean’s biological carbon cycle. About 50% of this production takes place in the dark ocean characterized by low temperature and high hydrostatic pressure. However, activity measurements of prokaryotic heterotrophic production are usually performed under atmospheric pressure conditions. The main aim of this study is to understand prokaryotic activity and metabolism under in situ hydrostatic pressure in the dark ocean. The main aim includes that determining the difference of deep-sea prokaryotic activity under in situ hydrostatic pressure and atmospheric pressure conditions to understand the effect of hydrostatic pressure on prokaryotic heterotrophic production. As a result, prokaryotic heterotrophic production under in situ pressure was generally lower than under atmospheric pressure condition, suggesting that incubation under atmospheric pressure on board stimulates activity of dark ocean prokaryotes.
Academic Significance and Societal Importance of the Research Achievements	現場培養機を用いた実水深での微生物群集の生物生産活性測定から、従来の中・深層海水を採取後船上培養することで得ていた微生物の生物生産活性は炭素代謝を過大評価している可能性が極めて高いと言える。圧力の減少は中・深層の微生物群集の生物活性を刺激するとも言え、大気圧下で行われた結果をもとに推定されている炭素需要について、特に深層で見直す必要があることを支持するものである。