Rates and physicochemical drivers of microbial anabolic activity in deep‐sea sediments and implications for deep time

Sediment microorganisms influence global climate and redox by altering rates of organic carbon burial. However, the activity and ecology of benthic microorganisms are poorly characterized, especially in the deep sea. Here, we conducted nearly 300 stable isotope tracer experiments in sediments from t...

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Bibliographic Details
Published in:Environmental microbiology 2022-11, Vol.24 (11), p.5188-5201
Main Authors: Meyer, Nicolette R., Parada, Alma E., Kapili, Bennett J., Fortney, Julian L., Dekas, Anne E.
Format: Article
Language:English
Subjects:
Ammonium
Ammonium compounds
Anabolism
Archaea
Archaea - genetics
Bacteria - genetics
Benthos
Biological activity
Carbon
Carbon fixation
Chemoautotrophy
Chlorophyll
Chlorophylls
Deep sea
Geologic Sediments - microbiology
Global climate
Inorganic carbon
Low concentrations
Microbial activity
Microorganisms
NifH gene
Nitrogen
Nitrogen fixation
Nitrogenation
Oceans
Organic carbon
Phylogeny
Pore water
RNA, Ribosomal, 16S - genetics
rRNA 16S
Sediment
Sediments
Spatial distribution
Stable isotopes
Tracers
Uptake
Water depth
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Summary:Sediment microorganisms influence global climate and redox by altering rates of organic carbon burial. However, the activity and ecology of benthic microorganisms are poorly characterized, especially in the deep sea. Here, we conducted nearly 300 stable isotope tracer experiments in sediments from the Pacific and Atlantic oceans (100–4500 m water depth) to determine the rates, spatial distribution, and physicochemical controls on microbial total anabolic activity, nitrogen fixation, and inorganic/organic carbon uptake. Using correlative and manipulative approaches, we find that total activity is limited primarily by organic carbon and/or energy. Activity correlates significantly with distance from shore, sediment depth, C:N ratios, and overlying chlorophyll concentrations and is stimulated by carbon but not nitrogen additions. Consistent with this, nitrogen fixation was undetected despite relatively low concentrations of porewater ammonium and the previous detection of nifH genes. Inorganic carbon uptake accounted for 7%–55% of carbon assimilation per sample (median 21%), suggesting chemoautotrophy is an important and unappreciated source of labile carbon in deep‐sea sediments. Community 16S rRNA was dominated by Bacteria (
ISSN:1462-2912
1462-2920
DOI:10.1111/1462-2920.16183