Nitrate Storage and Dissimilatory Nitrate Reduction by Eukaryotic Microbes
Anja Kamp1, Signe Høgslund2, Nils Risgaard-Petersen2
1AIAS, Aarhus Institute of Advanced Studies Aarhus University Aarhus, Denmark.
Frontiers in Microbiology
|January 7, 2016
Summary
Eukaryotic microbes, including diatoms and fungi, can store and use nitrate for energy in oxygen-poor environments. This finding challenges the long-held belief that only prokaryotes drive the nitrogen cycle.
Area of Science:
- Marine microbiology
- Biogeochemical cycles
- Eukaryotic metabolism
Background:
- The nitrogen cycle is crucial for Earth's ecosystems.
- Prokaryotic microbes were traditionally considered the sole mediators of the microbial nitrogen cycle.
- Recent discoveries reveal eukaryotic microbes also play a role.
Purpose of the Study:
- To review nitrate storage and dissimilatory nitrate reduction in marine eukaryotes.
- To explore the eco-physiological significance of this trait.
- To provide an overview of eukaryotic contributions to the nitrogen cycle.
Main Methods:
- Literature review of eukaryotic nitrate metabolism.
- Eco-physiological analysis of nitrate storage and use.
- Compilation of intracellular nitrate inventories in marine sediments.
- Estimation of eukaryotic contribution to denitrification.
Main Results:
- Eukaryotic microbes like diatoms, foraminifers, and fungi store nitrate intracellularly.
- Intracellular nitrate storage aids anaerobic energy conservation in oxygen-depleted habitats.
- Intracellular nitrate pools in sediments can exceed porewater nitrate pools.
- Eukaryotes may significantly contribute to sedimentary denitrification, potentially rivaling prokaryotes.
Conclusions:
- Eukaryotic nitrate metabolism represents a significant paradigm shift in understanding the nitrogen cycle.
- This trait enables unique lifestyles and energy conservation strategies for marine eukaryotes.
- Further research is needed to fully understand the evolutionary and ecological implications of eukaryotic nitrate metabolism.
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