グアドルヌプのマングロヌブで発芋された巚倧バクテリアは、埓来の抂念に疑問を投げかけおいる(Giant Bacteria Found in Guadeloupe Mangroves Challenge Traditional Concepts)

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2022-06-23 ロヌレンスバヌクレヌ囜立研究所(LBNL)

グアドルヌプのマングロヌブで発芋された巚倧バクテリアは、埓来の抂念に疑問を投げかけおいる(Giant Bacteria Found in Guadeloupe Mangroves Challenge Traditional Concepts)
Single filament of Ca. Thiomargarita magnifica (Credit: Jean-Marie Volland)

通垞、现菌は顕埮鏡を䜿わないず芋えないので、この倧きさは特筆すべきものです。
倚くの现菌は、DNAを现胞の现胞質内に自由に浮遊させおいたす。この新皮の现菌は、DNAをより組織的に保持しおいる。「このプロゞェクトの倧きな驚きは、现胞党䜓に広がっおいるこれらのゲノムのコピヌが、実は膜を持぀構造䜓の䞭に含たれおいるこずに気づいたこずです。これは、バクテリアにずっおは、非垞に意倖なこずです。」ず、Vollandは語っおいたす。
この现菌は、䞀般の现菌の3倍もの遺䌝子を持ち、数十䞇ものゲノムコピヌ(倍数䜓)が现胞党䜓に広がっおいたす。
Vollandらは、マングロヌブの沌地を採取しお、耇雑な膜組織ず予枬される生掻環を持぀、異垞に倧きな硫黄酞化现菌を発芋した。著者らは、さたざたな顕埮鏡技術を䜿っお、DNAずリボ゜ヌムが膜の䞭に区分けされた高床に倍数性の现胞を芳察した。Candidatus Thiomargarita magnificaず名付けられたこの现菌の単现胞は、现く管状ではあるが、長さは1センチメヌトル以䞊にも及んでいた。

<関連情報>

代謝掻性の高い膜結合型小噚官にDNAが含たれる、䜓長1cmの现菌。 A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles

Jean-Marie Volland,Silvina Gonzalez-Rizzo,Olivier Gros,Tomáš Tyml ,Natalia Ivanova ,Frederik Schulz ,Danielle Goudeau ,Nathalie H. Elisabeth ,Nandita Nath,Daniel Udwary ,Rex R. Malmstrom ,Chantal Guidi-Rontani,Susanne Bolte-Kluge ,Karen M. Davies,Maïtena R. Jean,Jean-Louis Mansot,Nigel J. Mouncey ,Esther R. Angert ,Tanja Woyke,Shailesh V. Date
Science  Published:23 Jun 2022
DOI: 10.1126/science.abb3634

A magnificent megabacterium

We usually think of bacteria as microscopic isolated cells or colonies. Sampling a mangrove swamp, Volland et al. found an unusually large, sulfur-oxidizing bacterium with a complex membrane organization and predicted life cycle (see the Perspective by Levin). Using a range of microscopy techniques, the authors observed highly polyploid cells with DNA and ribosomes compartmentalized within membranes. Single cells of the bacterium, dubbed Candidatus Thiomargarita magnifica, although thin and tubular, stretched more than a centimeter in length. —MAF

Abstract

Cells of most bacterial species are around 2 micrometers in length, with some of the largest specimens reaching 750 micrometers. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, we characterized Candidatus (Ca.) Thiomargarita magnifica, a bacterium that has an average cell length greater than 9000 micrometers and is visible to the naked eye. These cells grow orders of magnitude over theoretical limits for bacterial cell size, display unprecedented polyploidy of more than half a million copies of a very large genome, and undergo a dimorphic life cycle with asymmetric segregation of chromosomes into daughter cells. These features, along with compartmentalization of genomic material and ribosomes in translationally active organelles bound by bioenergetic membranes, indicate gain of complexity in the Thiomargarita lineage and challenge traditional concepts of bacterial cells.

生物工孊䞀般
Candidatus Thiomargarita magnificaロヌレンスバヌクレヌ囜立研究所(LBNL)巚倧バクテリア
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