Abstract
Biological nitrogen (N2) fixation is important in controlling biological productivity and carbon flux in the oceans. Unicellular N2-fixing cyanobacteria have only recently been discovered and are widely distributed in tropical and subtropical seas. Metagenomic analysis of flow cytometry-sorted cells shows that unicellular N2-fixing cyanobacteria in "group A" (UCYN-A) lack genes for the oxygen-evolving photosystem II and for carbon fixation, which has implications for oceanic carbon and nitrogen cycling and raises questions regarding the evolution of photosynthesis and N2 fixation on Earth.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Cyanobacteria / cytology
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Cyanobacteria / genetics*
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Cyanobacteria / isolation & purification
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Cyanobacteria / metabolism*
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Evolution, Molecular
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Flow Cytometry
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Genes, Bacterial
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Genes, rRNA
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Genome, Bacterial
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Genomics / methods
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Molecular Sequence Data
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Nitrogen Fixation / genetics*
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Oxidoreductases / genetics
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Pacific Ocean
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Photosynthesis
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Photosystem II Protein Complex / genetics*
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Photosystem II Protein Complex / metabolism
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Phylogeny
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Seawater / microbiology*
Substances
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Photosystem II Protein Complex
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Oxidoreductases
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nitrogenase reductase