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Updated: Jun 22, 2026
08:05
Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Widespread metabolic potential for nitrite and nitrate assimilation among Prochlorococcus ecotypes
Adam C Martiny1, Satish Kathuria, Paul M Berube
1Department of Earth System Science and Ecology, University of California, Irvine, CA 92697, USA. amartiny@uci.edu
Summary
Marine cyanobacteria Prochlorococcus possess novel genes enabling nitrate assimilation, challenging previous assumptions about their distribution and role in oceanic nitrogen cycling. This discovery impacts our understanding of marine microbial ecosystems.
Area of Science:
- Marine microbiology
- Oceanography
- Genomics
Background:
- Prochlorococcus is the most abundant photosynthetic organism in the ocean.
- Its inability to assimilate nitrate was thought to limit its distribution in certain marine zones.
Purpose of the Study:
- To investigate the occurrence and function of nitrite and nitrate assimilation genes in Prochlorococcus.
- To challenge existing assumptions about Prochlorococcus's nitrogen metabolism and biogeography.
Main Methods:
- Genomic analysis of uncultured Prochlorococcus cells.
- Phylogenetic analysis of identified genes.
- Functional validation of gene products.
- Expression analysis in marine environments.
Main Results:
- Widespread genomic island containing nitrite and nitrate assimilation genes found in Prochlorococcus.
- Genes are phylogenetically distinct from Synechococcus and encode functional, expressed proteins.
- Gene occurrence varies geographically, potentially linked to nitrogen availability.
- Ability to assimilate nitrate is linked to specific Prochlorococcus lineages and ecotypes.
Conclusions:
- Prochlorococcus can assimilate nitrate, contrary to prior beliefs.
- Nitrite assimilation is not exclusive to low-light adapted ecotypes.
- This finding reshapes understanding of Prochlorococcus biogeography and its role in oceanic carbon and nitrogen cycles.
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