English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Microscopic counts of microbial cells in deep sediment cores retrieved by scientific ocean drilling have revealed the largest living ecosystem on earth: the deep biosphere (1, 2). Hidden beneath the seafloor, a large part of all prokaryotic cells on earth persist under conditions so highly energy-limited that it seems to violate the constraints to life. This deep biosphere is the most understudied ecosystem, inhabited by organisms only distantly related to known laboratory strains. It is not even clear whether the cells are alive and metabolically active, or are dormant or perhaps dead. The report by Morono et al. in PNAS (3) attacks this very basic question with new convincing experiments. The idea of Morono et al. has been that, even though the deep biosphere is highly energy-starved under natural conditions, the organisms may still have the capacity to feed very actively if served a rich and varied diet of organic substrates. The authors therefore performed experiments with sediment from several hundred meters’ depth in the seabed of the Japan Sea and fed the inhabiting microorganisms a mixture of stable isotope-labeled carbon and nitrogen compounds. After 2 mo, they extracted the cells from the mud and analyzed the increase in cell numbers and fraction of all cells that had taken up the isotopes, 13C or 15N. For this purpose, they used a nanometer-scale secondary ion mass spectrometer with which they could identify individual isotope-labeled cells and even determine how much of the substrates each cell had taken up and incorporated into its biomass. The novelty of this study is not so much that it reveals the mode of life of these deep-living microorganisms in their natural environment. In that respect, the substrate concentrations offered to the cells were orders of magnitude too high compared with what these cells …

Deep subseafloor microbial cells on physiological standby