No evidence of phago-mixotropy in Micromonas polaris , the dominant picophytoplankton species in the Arctic

• Main Authors: Jimenez, Valeria, Burns, John, Le Gall, Florence, Not, Fabrice, Vaulot, Daniel
• Other Authors: Adaptation et diversité en milieu marin (ADMM), Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff = Roscoff Marine Station (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Report
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDE]Environmental Sciences; Arctic Ocean; Phytoplankton
• Online Access: https://hal.science/hal-03972015; https://doi.org/10.1101/2020.05.26.117895

ABSTRACT In the Arctic Ocean, the small green alga Micromonas polaris dominates pico-phytoplankton during the summer months. It has been previously hypothesized to be phago-mixotrophic (capable of bacteria ingestion) based on laboratory and field experiments. Prey uptake was analysed in several M. polaris strains isolated from different regions and depths of the Arctic Ocean. Using both fluorescent beads and fluorescently labelled bacteria as prey, we found no evidence of phago-mixotrophy in any M. polaris strain by flow cytometric measurement of prey ingestion. In addition, in silico predictions reveal that members of the genus Micromonas lack a genetic signature of phagocytotic capacity.