Microbial iron metabolism as revealed by gene expression profiles in contrasted Southern Ocean regimes

• Published in: Environmental Microbiology
• Main Authors: Debeljak, Pavla, Toulza, Eve, Beier, Sara, Blain, Stéphane, Obernosterer, Ingrid
• Other Authors: Laboratoire d'Océanographie Microbienne (LOMIC), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Interactions Hôtes-Pathogènes-Environnements (IHPE), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Perpignan Via Domitia (UPVD), Leibniz-Institut für Ostseeforschung Warnemünde (IOW), Leibniz Association
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: envir; geo; Southern Ocean
• Online Access: https://doi.org/10.1111/1462-2920.14621; https://hal.archives-ouvertes.fr/hal-02381765/file/Debeljak2019EnvMicrobiol.pdf; https://hal.archives-ouvertes.fr/hal-02381765

International audience Iron (Fe) is a limiting nutrient in large regions of the ocean, but the strategies of prokaryotes to cope with this micronutrient are poorly known. Using a gene‐specific approach from metatranscriptomics data, we investigated seven Fe‐related metabolic pathways in microbial communities from high nutrient low chlorophyll and naturally Fe‐fertilized waters in the Southern Ocean. We observed major differences in the contribution of prokaryotic groups at different taxonomic levels to transcripts encoding Fe‐uptake mechanisms, intracellular Fe storage and replacement and Fe‐related pathways in the tricarboxylic acid (TCA) cycle. The composition of the prokaryotic communities contributing to the transcripts of a given Fe‐related pathway was overall independent of the in situ Fe supply, indicating that microbial taxa utilize distinct Fe‐related metabolic processes. Only a few prokaryotic groups contributed to the transcripts of more than one Fe‐uptake mechanism, suggesting limited metabolic versatility. Taxa‐specific expression of individual genes varied among prokaryotic groups and was substantially higher for all inspected genes in Fe‐limited as compared to naturally fertilized waters, indicating the link between transcriptional state and Fe regime. Different metabolic strategies regarding low Fe concentrations in the Southern Ocean are discussed for two abundant prokaryotic groups, Pelagibacteraceae and Flavobacteriaceae.