Related Experiment Video
Updated: Mar 13, 2026

Luciferase Complementation Imaging Assay in Nicotiana benthamiana Leaves for Transiently Determining Protein-protein Interaction Dynamics
Published on: November 20, 2017
Nitrogen fixation in a chemoautotrophic lucinid symbiosis
Sten König1,2, Olivier Gros2, Stefan E Heiden1
1Department of Pharmaceutical Biotechnology, E.M.A. University of Greifswald, Institute of Pharmacy, Greifswald, Germany.
Abstract:
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.
More Related Videos
14:38Establishment of Microbial Eukaryotic Enrichment Cultures from a Chemically Stratified Antarctic Lake and Assessment of Carbon Fixation Potential
Published on: April 20, 2012
05:52In Situ Measurement and Correlation of Cell Density and Light Emission of Bioluminescent Bacteria
Published on: June 28, 2018
Related Concept Videos
Inorganic Nitrogen Assimilation
Metabolism of Chemolithotrophs
Carbon-dioxide Fixation
Anoxygenic Photosynthesis
Microbial Nutrition
The Nitrogen Cycle