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Cryptic metabolisms in anoxic subseafloor sediment
Arkadiy I Garber1, Gustavo A Ramírez2,3,4, Sean M McAllister5,6
1School of Life Sciences, Arizona State University, Tempe, AZ, USA.
Environmental Microbiology Reports
|June 29, 2021
Summary
Microbial communities in deep seafloor sediment utilize diverse electron acceptors, including oxygen from water radiolysis. This cryptic metabolism aids long-term survival in energy-limited environments.
Area of Science:
- Microbiology
- Geochemistry
- Oceanography
Background:
- Anoxic subseafloor sediment presents extreme energy limitations for microbial life.
- Understanding microbial metabolism in these environments is crucial for comprehending deep biosphere survival strategies.
Purpose of the Study:
- To investigate microbial gene expression in anoxic subseafloor sediments from the Baltic Sea and Peru Margin.
- To identify the electron acceptors utilized by microbial communities in these deep environments.
Main Methods:
- Analysis of microbial gene expression data from subseafloor sediment samples.
- Identification of transcripts encoding proteins involved in metabolic processes.
Main Results:
- Diverse transcripts indicate microbial utilization of various electron acceptors, including oxygen, nitrate, arsenate, and selenate.
- Catalase transcripts suggest an in situ oxygen source from reactive oxygen species neutralization.
- Evidence for oxidation of iron and sulfur was also detected.
Conclusions:
- Microbial communities in subseafloor sediments employ a surprisingly diverse range of electron acceptors.
- Radiolysis of water and sediment interactions continuously supply electron acceptors and hydrogen.
- Cryptic microbial metabolism of these substrates is a key survival mechanism in energy-limited deep-sea environments.
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