Deep-sea hydrothermal vent Epsilonproteobacteria encode a conserved and widespread nitrate reduction pathway (Nap)
Costantino Vetriani1, James W Voordeckers1, Melitza Crespo-Medina1
11] Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, USA [2] Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA.
The ISME Journal
|January 17, 2014
Summary
Nitrate reduction is common in deep-sea vent Epsilonproteobacteria, with the periplasmic nitrate reductase complex (nap) gene highly conserved. This adaptation is crucial for energy metabolism in low-nitrate vent environments.
Area of Science:
- Microbiology
- Marine Biology
- Biogeochemistry
Background:
- Epsilonproteobacteria are frequently isolated from deep-sea hydrothermal vents and are known to respire nitrate.
- The genetic basis for nitrate reduction in these deep-sea microorganisms remains largely unexplored.
Purpose of the Study:
- To investigate the genes responsible for the nitrate reduction pathway in deep-sea vent Epsilonproteobacteria.
- To determine the conservation and expression of the periplasmic nitrate reductase complex (nap) genes in these environments.
Main Methods:
- Analysis of the gene cluster for the periplasmic nitrate reductase complex (nap) in chemolithoautotrophic, nitrate-reducing Epsilonproteobacteria.
- Gene expression analysis of napA in pure cultures of vent Epsilonproteobacteria.
- Assessment of napA conservation in microbial communities from diverse deep-sea vent conditions.
Main Results:
- The nap gene cluster is highly conserved among nitrate-reducing Epsilonproteobacteria from deep-sea hydrothermal vents.
- The napA gene is expressed in pure cultures and conserved across various vent temperature and redox regimes.
- Higher diversity of nitrate-reducing Epsilonproteobacteria was observed in moderate-temperature, diffuse-flow vents compared to high-temperature or low-temperature vents.
Conclusions:
- The high-affinity NapA enzyme likely represents an adaptation to low nitrate concentrations in vent fluids.
- Nitrate reduction is a widespread metabolic capability in deep-sea vent Epsilonproteobacteria, contributing to energy metabolism.
- The conserved nap cluster suggests the importance of nitrate respiration in diverse habitats, including the human body.
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