Nitrogen fixation in the widely distributed marine γ-proteobacterial diazotroph Candidatus Thalassolituus haligoni

• Published in: Science Advances
• Main Authors: Rose, Sonja, Robicheau, Brent, Tolman, Jennifer, Fonseca-Batista, Debany, Rowland, Elden, Desai, Dhwani, Ratten, Jenni-Marie, Kantor, Ella Joy H., Comeau, André, Langille, Morgan G.I., Jerlström-Hultqvist, Jon, Devred, Emmanuel, Sarthou, Géraldine, Bertrand, Erin, Laroche, Julie
• Other Authors: Dalhousie University Halifax, Uppsala Universitet Uppsala, Institut océanographique Bedford - Bedford Oceanographic Institute Dartmouth, Canada (IOB), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), The French National Centre for Scientific Research (CNRS-LEFE-CYBER), LabexMER (ANR-10-LABX-19), Ifremer, Logistics were supported by DT-INSU and GENAVIR, ANR-13-BS06-0014,GEOVIDE,GEOVIDE, Une étude internationale GEOTRACES le long de la section OVIDE en Atlantique Nord et en Mer du Labrador(2013)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Arctic Ocean
• Online Access: https://hal.science/hal-04666250; https://hal.science/hal-04666250/document; https://hal.science/hal-04666250/file/Rose%20et%20al%202024.pdf; https://doi.org/10.1126/sciadv.adn1476

International audience The high diversity and global distribution of heterotrophic bacterial diazotrophs (HBDs) in the ocean has recently become apparent. However, understanding the role these largely uncultured microorganisms play in marine N 2 fixation poses a challenge due to their undefined growth requirements and the complex regulation of the nitrogenase enzyme. We isolated and characterized Candidatus Thalassolituus haligoni, a member of a widely distributed clade of HBD belonging to the Oceanospirillales. Analysis of its nifH gene via amplicon sequencing revealed the extensive distribution of Cand. T. haligoni across the Pacific, Atlantic, and Arctic Oceans. Pangenome analysis indicates that the isolate shares >99% identity with an uncultured metagenome-assembled genome called Arc-Gamma-03, recently recovered from the Arctic Ocean. Through combined genomic, proteomic, and physiological approaches, we confirmed that the isolate fixes N 2 gas. However, the mechanisms governing nitrogenase regulation in Cand. T. haligoni remain unclear. We propose Cand. T. haligoni as a globally distributed, cultured HBD model species within this understudied clade of Oceanospirillales.