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Agarose-Based Model Ecosystem for Cultivating Methanotrophs in a Methane-Oxygen Counter Gradient
Published on: September 6, 2024
Deep-sea archaea fix and share nitrogen in methane-consuming microbial consortia
Anne E Dekas1, Rachel S Poretsky, Victoria J Orphan
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. dekas@gps.caltech.edu
Science (New York, N.Y.)
|October 17, 2009
Summary
Deep-sea archaea fix nitrogen (N2) and share it with bacterial symbionts. This discovery reveals these microbes are key players in oceanic carbon, nitrogen, and sulfur cycles.
Area of Science:
- Marine microbiology
- Biogeochemistry
- Microbial ecology
Background:
- Diazotrophic microorganisms are crucial for ecosystem productivity.
- The identity of diazotrophs in many oceanic environments remains largely unknown.
- Anaerobic methane-oxidizing archaea and their bacterial symbionts are significant methane sinks in deep-sea ecosystems.
Purpose of the Study:
- To identify diazotrophs in deep-sea environments.
- To investigate the role of anaerobic methane-oxidizing archaea in nitrogen fixation.
- To understand the symbiotic relationship between archaea and bacteria in nutrient cycling.
Main Methods:
- Single-cell-resolution nanometer secondary ion mass spectrometry (NanoSIMS) imaging.
- 15N incorporation analysis to track nitrogen fixation.
- Stable isotope probing to elucidate metabolic pathways.
Main Results:
- Deep-sea anaerobic methane-oxidizing archaea were identified as nitrogen-fixing organisms.
- These archaea fix both N2 and structurally similar compounds like CN-.
- Nitrogen fixation products are shared with sulfate-reducing bacterial symbionts.
- Archaeal methane oxidation rates were maintained during nitrogen fixation, but growth rates decreased.
- These archaeal/bacterial consortia are a newly identified source of bioavailable nitrogen.
Conclusions:
- Deep-sea archaea contribute significantly to oceanic nitrogen cycling.
- The identified archaeal/bacterial consortia link global carbon, nitrogen, and sulfur cycles.
- This study expands the understanding of the energetic limits for nitrogen fixation in microbial communities.
- The findings highlight the crucial role of symbiotic relationships in biogeochemical processes.
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