No evidence of Phago‐mixotropy in Micromonas polaris (Mamiellophyceae), the Dominant Picophytoplankton Species in the Arctic

• Published in: Journal of Phycology
• Main Authors: Jimenez, Valeria, Burns, John, Le Gall, Florence, Not, Fabrice, Vaulot, Daniel
• Other Authors: Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ECOlogy of MArine Plankton (ECOMAP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Bigelow Laboratory for Ocean Sciences, Nanyang Technological University Singapour
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: phytoplankton; Arctic; Micromonas; phago-mixotrophy; MESH: Arctic Regions; MESH: Bacteria; MESH: Chlorophyta; MESH: Seasons; [SDV]Life Sciences [q-bio]; Arctic Ocean; Phytoplankton
• Online Access: https://hal.sorbonne-universite.fr/hal-03267092; https://hal.sorbonne-universite.fr/hal-03267092/document; https://hal.sorbonne-universite.fr/hal-03267092/file/Jimenez%20et%20al.%20-%20No%20evidence%20of%20Phago-mixotropy%20in%20Micromonas%20polar.pdf; https://doi.org/10.1111/jpy.13125

International audience In the Arctic Ocean, the small green alga Micromonas polaris dominates picophytoplankton during the summer months but is also present in winter. It has been previously hypothesized to be phago-mixotrophic (capable of bacteria ingestion) based on laboratory and field experiments. Prey uptake was analyzed in several M. polaris strains isolated from different regions and depths of the Arctic Ocean and in Ochromonas triangulata, a known phago-mixotroph used as a control. Measuring ingestion of either fluorescent beads or fluorescently labeled bacteria by flow cytometry, we found no evidence of phago-mixotrophy in any M. polaris strain while O. triangulata was ingesting both beads and bacteria. In addition, in silico predictions revealed that members of the genus Micromonas lack a genetic signature of phagocytotic capacity.