DATE2024.11.05 #Press Releases
Uncovering the Mysterious Ecology of Primitive Archaea Hidden in the Dark Biosphere
—— The growth key found inside a deep-sea vent chimney——
Summary
A joint research group led by Associate Professor Yohei Suzuki at the School of Science, the University of Tokyo, and consisting of researchers from the Graduate School of Agricultural and Life Sciences, the University of Tokyo, Keio University, RIKEN, Hiroshima University, and the Japan Synchrotron Radiation Research Institute, has examined the interior of a chimney collected from a deep-sea hydrothermal field in the southern Mariana Trough. The inner wall of the chimney was found to be massive chalcopyrite, and microorganisms were found to be densely packed in the silica-filled network of chalcopyrite grain boundaries inside the inner chimney wall. Only the inner chimney wall was removed from the chimney structure and subjected to the extraction of DNA and proteins for metagenomic and metaproteomic analyses. The genomic information revealed that 30% of microorganisms were DPANN archaea, which lacked many genes essential to maintain cellular activities. However, the expressed proteins contained genes that produce energy through fermentation, clarifying that they were metabolically active inside the chimney. Since DPANN archaea, minor portions of which have been successfully cultured so far, are known to be ectosymbiotic with their host archaea, it was expected that they would also be ectosymbiotic in the environment. Unexpectedly, the DPANN archaea that dominate inside chimneys are not ectosymbionts, suggesting that they have a free-living life style. It is also clarified that the lack of genes essential to the growth is supported by the functions of minerals in the chimney interior, which may reflect a primitive lifestyle at the very early evolutionary stage of life.
Figure：Habitat of microorganisms at the beginning of the evolution of life
Links：RIKEN, SPring-8・JASRI, Graduate School of Agricultural and Life Sciences, The University of Tokyo. （in Japanese）
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