Geochemical and microbiological insights into co-evolution of life and material dynamics on the early Earth

• Nishizawa Manabu

  Laboratory of Ocean-Earth Life Evolution Research (OELE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Bibliographic Information

Other Title

• 生命の初期進化と物質動態に関する地球化学的，微生物学的研究
• 2011年度日本地球化学会奨励賞受賞記念論文 生命の初期進化と物質動態に関する地球化学的,微生物学的研究
• 2011ネンド ニホン チキュウ カガッカイ ショウレイショウ ジュショウ キネン ロンブン セイメイ ノ ショキ シンカ ト ブッシツ ドウタイ ニ カンスル チキュウ カガクテキ,ビセイブツガクテキ ケンキュウ

Abstract

Nitrogen is essential for all life as it is a major element of protein and nucleic acid. However, many of the living organisms cannot assimilate dinitrogen (N₂), the most abundant nitrogen compound in the atmosphere-hydrosphere. Primary production of marine ecosystem is thus limited by the availability of fixed nitrogen ultimately originated from nitrogen fixation, the process that converts dinitrogen to ammonia, catalyzed by a limited member of prokaryote with nitrogenase enzyme. To constrain the time and place of the onset of nitrogen fixation from geological records, I have determined nitrogen isotopic ratio of Archean atmosphere preserved as fluid inclusion within hydrothermal deposits at 3.5 Ga. The estimated δ¹⁵N(N₂) value of the Archean atmosphere (-2～0‰) is similar to the present-day atmosphere (0‰). Subsequently, I have determined physiological properties and isotopic characteristics of nitrogen fixation by methanogenic archaea commonly found in deep-sea hydrothermal environments. The experimental results demonstrate that hyperthermophilic methanogens can assimilate dinitrogen actively under simulated Archean oceanic conditions (i.e., Mo-depleted and Fe-enriched conditions). Further, ancient microbial ecosystems supported by nitrogen fixation in hyperthermophilic methanogens are deduced from the isotopic relationship between N₂ and organic nitrogen of the 3.5 Ga hydrothermal deposits, which also preserve chemical fossils of methanogenesis. These results imply the possibility that genes for nitrogen fixation had been transferred horizontally from hyperthermophilic methanogen to proto-photosynthetic bacteria in Archean hydrothermal environments, allowing rapid expansion of the microbial ecosystems on the sea surface immediately after the onset of photosynthesis. This paper also reviews the current state of knowledge of 1) the time of the emergence of life, 2) energy metabolisms of the microbial communities in Archean hydrothermal environments, and 3) the origin of oxygenic photosynthesis.

Journal

• Chikyukagaku

  Chikyukagaku 48 (3), 169-186, 2014

  The Geochemical Society of Japan

Keywords

• Early Earth
• Hydrothermal system
• Early life
• Energy metabolism
• Nitrogen fixation
• Oxygenic photosynthesis

Details

• CRID: 1390001205743012608
• NII Article ID: 130004698008
• NII Book ID: AN00141280
• DOI: 10.14934/chikyukagaku.48.169
• ISSN: 21885923
• ISSN: 03864073
• NDL BIB ID: 025847871
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I025847871
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed