Nitrogen fixation in a chemoautotrophic lucinid symbiosis

König Sten, Gros Olivier, Heiden Stefan E., Hinzke Tjorven, Thürmer Thomas, Poehlein Anja, Meyer Susann, Vatin Magalie, Mbéguié-A-Mbéguié Didier, Tocny Jennifer, Ponnudurai Ruby, Daniel Rolf, Becher Dörte, Schweder Thomas, Markert Stephanie. 2017. Nitrogen fixation in a chemoautotrophic lucinid symbiosis. Nature Microbiology, 2 (1):e16193, 10 p.

Quartile : Outlier, Sujet : MICROBIOLOGY

Résumé : The shallow water bivalve Codakia orbicularis lives in symbiotic association with a sulfur-oxidizing bacterium in its gills. The endosymbiont fixes CO2 and thus generates organic carbon compounds, which support the host's growth. To investigate the uncultured symbiont's metabolism and symbiont–host interactions in detail we conducted a proteogenomic analysis of purified bacteria. Unexpectedly, our results reveal a hitherto completely unrecognized feature of the C. orbicularis symbiont's physiology: the symbiont's genome encodes all proteins necessary for biological nitrogen fixation (diazotrophy). Expression of the respective genes under standard ambient conditions was confirmed by proteomics. Nitrogenase activity in the symbiont was also verified by enzyme activity assays. Phylogenetic analysis of the bacterial nitrogenase reductase NifH revealed the symbiont's close relationship to free-living nitrogen-fixing Proteobacteria from the seagrass sediment. The C. orbicularis symbiont, here tentatively named 'Candidatus Thiodiazotropha endolucinida', may thus not only sustain the bivalve's carbon demands. C. orbicularis may also benefit from a steady supply of fixed nitrogen from its symbiont—a scenario that is unprecedented in comparable chemoautotrophic symbioses.

Mots-clés Agrovoc : Fixation de l'azote, Codakia orbicularis, symbiose, Bivalvia, activité enzymatique, symbiote, diazotrophie

Classification Agris : M40 - Écologie aquatique

Champ stratégique Cirad : Hors axes (2014-2018)

Agences de financement européennes : European Commission

Programme de financement européen : FP7

Projets sur financement : (EU) Molecular Ecology and Evolution of Bacterial Symbionts

Auteurs et affiliations

• König Sten, Ernst Moritz Arndt University of Greifswald (DEU)
• Gros Olivier, UAG (GLP)
• Heiden Stefan E., Ernst Moritz Arndt University of Greifswald (DEU)
• Hinzke Tjorven, Ernst Moritz Arndt University of Greifswald (DEU)
• Thürmer Thomas, Göttingen Genomics Laboratory (DEU)
• Poehlein Anja, Göttingen Genomics Laboratory (DEU)
• Meyer Susann, Ernst Moritz Arndt University of Greifswald (DEU)
• Vatin Magalie, Université des Antilles (GLP)
• Mbéguié-A-Mbéguié Didier, CIRAD-PERSYST-UMR Qualisud (GLP) ORCID: 0000-0002-9256-3999
• Tocny Jennifer, Université des Antilles (GLP)
• Ponnudurai Ruby, Ernst Moritz Arndt University of Greifswald (DEU)
• Daniel Rolf, Göttingen Genomics Laboratory (DEU)
• Becher Dörte, Ernst Moritz Arndt University of Greifswald (DEU)
• Schweder Thomas, Ernst Moritz Arndt University of Greifswald (DEU)
• Markert Stephanie, Ernst Moritz Arndt University of Greifswald (DEU)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/584642/)

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