• Microbial diversity below seafloor is as

    From ScienceDaily@1337:3/111 to All on Tue Oct 20 21:30:46 2020
    Microbial diversity below seafloor is as rich as on Earth's surface


    Date:
    October 20, 2020
    Source:
    University of Rhode Island
    Summary:
    For the first time, researchers have mapped the biological diversity
    of marine sediment, one of Earth's largest global biomes. The
    research team discovered that microbial diversity in the dark,
    energy-limited world beneath the seafloor is as diverse as in
    Earth's surface biomes.



    FULL STORY ==========================================================================
    For the first time, researchers have mapped the biological diversity of
    marine sediment, one of Earth's largest global biomes. Although marine
    sediment covers 70% of the Earth's surface, little was known about its
    global patterns of microbial diversity.


    ==========================================================================
    A team of researchers from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), the University of Hyogo, the University of Kochi,
    the University of Bremen, and the University of Rhode Island delineated
    the global diversity of microbes in marine sediment. For the study,
    published in the Proceedings of the National Academy of Sciences,
    Tatsuhiko Hoshino, senior researcher at JAMSTEC, and his colleagues
    including URI Graduate School of Oceanography Professor Steven D'Hondt
    analyzed 299 samples of marine sediment collected as core samples from 40
    sites around the globe. Their sample depths ranged from the seafloor to
    678 meters below it. To accurately determine the diversity of microbial communities, the authors extracted and sequenced DNA from each frozen
    sample under the same clean laboratory condition.

    The 16S rRNA gene sequences (approximately 50 million sequences)
    obtained through comprehensive next-generation sequencing were analyzed
    to determine microbial community composition in each sample. From
    these 50 million sequences, the research team discovered nearly 40,000 different types of microorganisms in marine sediment, with diversity
    generally decreasing with depth. The team found that microbial community composition differs significantly between organic-rich sediment of
    continental margins and nutrient-poor sediment of the open ocean, and
    that the presence or absence of oxygen and the concentration of organic
    matter are major factors in determining community composition.

    By comparing their results to previous studies of topsoil and seawater,
    the researchers discovered that each of these three global biomes
    -- marine sediment, topsoil, and seawater -- has different microbial communities but similar total diversity. "It was an unexpected discovery
    that microbial diversity in the dark, energy-limited world beneath the
    seafloor is as diverse as in Earth's surface biomes," said Hoshino.

    Furthermore, by combining the estimates of bacterial and archaeal
    diversity for these three biomes, the researchers found that bacteria
    are far more diverse than archaea -- microbes distinct from bacteria
    and known for living in extreme environments -- on Earth.

    "In this respect as well, microbial diversity in the dark realm of
    marine sediment resembles microbial diversity in the surface world,"
    said D'Hondt.

    "It's exciting to glimpse the biological richness of this dark world."

    ========================================================================== Story Source: Materials provided by University_of_Rhode_Island. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Tatsuhiko Hoshino, Hideyuki Doi, Go-Ichiro Uramoto, Lars Wo"rmer,
    Rishi
    R. Adhikari, Nan Xiao, Yuki Morono, Steven D'Hondt, Kai-Uwe
    Hinrichs, Fumio Inagaki. Global diversity of microbial communities
    in marine sediment. Proceedings of the National Academy of Sciences,
    2020; 201919139 DOI: 10.1073/pnas.1919139117 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2020/10/201020131353.htm

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