著者

長沼 毅

出版者

Tokyo Geographical Society

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.2, pp.226-233, 2003-04-25

参考文献数

45

被引用文献数

4 3

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The search for life on the edges (frontiers) of the global biosphere bridges earth-bound biology and exobiology. This communication reviews recent microbiological studies on selected "frontiers", <I>i.e</I>., deep-sea, deep subsurface, and Antarctica. Deep-sea is characterized as the aphotic (non-photosynthetic) habitat, and the primary production is mostly due to the chemosynthetic autotrophy at the hydrothermal vents and methane-rich seeps. Formation of the chemosynthesis-dependent animal communities in the deep leads to the idea that such communities may be found in the "ocean" of the Jovian satellite, Europa. An anoxic (no-O<SUB>2</SUB>), as well as aphotic, condition is characteristic of the deep subsurface biosphere. Microorganisms in the deep subsurface biosphere exploit every available oxidant for anaerobic respiration. Sulfate, nitrate, iron (III) and CO<SUB>2</SUB> are the representative oxidants in the deep subsurface. Below the 3000 m-thick glacier on Antarctica, >70 lakes having liquid water are entombed. One of such sub-glacial lakes, Lake Vostok, has been a target of "life in extreme environments" and is about to be drill-penetrated for microbiological studies. These biospheric frontiers will provide new knowledge about the diversity and the potential of life on Earth and facilitate the capability of astrobiologial exploration.