高圧技術が切り開いた深海探査と暗黒の生態系の世界

抄録

It is more than 60 years since certain microbial populations were first discovered in deep-sea environments such as abyssal and hadal zones (>4000m) of ocean. According to the development of deep-sea technology and various sampling tools, the microbiological explorations have renewed our view of deep-sea microbial ecosystems: it was previously considered to be the static habitats and communities composed of minor extremophilic and long-surviving populations successively from the surface and overlying ocean environments while it is being recognized as the dynamic habitats and communities composed of genetically diverse and functionally active populations responding to variable oceanographic, geological and geochemical events and impacts. The most outstanding examples are discoveries of dark energy ecosystems in the deep-sea and subseafloor environments, represented by various types of chemosynthetic microbial communities completely independent of photosynthetic production in the deep-sea hydrothermal systems, an enormous biomass and diversity of deep subseafloor microbial communities beneath the global oceanfloor, and unique hadal biosphere at great depths of >6000m in ultradeep trenches. The findings have revolutionized our understanding of limits of life and biosphere and the origin and early evolution of life in the Earth. Even very recently, the previously unknown microbial ecosystem has been being found in the deep-sea and subseafloor environments. I can be proud that Japanese deep-sea exploration techniques and microbiologists have greatly contributed to these findings. In this article, the brief history and recent advance are reviewed.