title: Dynamic metabolic exchange governs a marine algal-bacterial interaction.
abstract: Emiliania huxleyiis a model coccolithophore micro-alga that generates vast blooms in the ocean. Bacteria are not considered among the major factors influencing coccolithophore physiology. Here we show through a laboratory model system that the bacteriumPhaeobacter inhibens, a well-studied member of the Roseobacter group, intimately interacts withE. huxleyi.While attached to the algal cell, bacteria initially promote algal growth but ultimately kill their algal host. Both algal growth enhancement and algal death are driven by the bacterially-produced phytohormone indole-3-acetic acid. Bacterial production of indole-3-acetic acid and attachment to algae are significantly increased by tryptophan, which is exuded from the algal cell. Algal death triggered by bacteria involves activation of pathways unique to oxidative stress response and programmed cell death. Our observations suggest that bacteria greatly influence the physiology and metabolism ofE. huxleyi.Coccolithophore-bacteria interactions should be further studied in the environment to determine whether they impact micro-algal population dynamics on a global scale.
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.
authors.forename: Einat
authors.identifier: 0000-0002-2266-1219
authors.initials: E
authors.lastname: Segev
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Wyche
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States.
authors.forename: Ki Hyun
authors.identifier: 0000-0002-5285-9138
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Petersen
authors.affiliation: Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany.
authors.forename: Claire
authors.initials: C
authors.lastname: Ellebrandt
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.
authors.forename: Hera
authors.initials: H
authors.lastname: Vlamakis
authors.affiliation: Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, United States.
authors.forename: Natasha
authors.initials: N
authors.lastname: Barteneva
authors.affiliation: Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, United States.
authors.forename: Joseph N
authors.initials: JN
authors.lastname: Paulson
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.
authors.forename: Liraz
authors.initials: L
authors.lastname: Chai
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States.
authors.forename: Jon
authors.identifier: 0000-0003-0213-8356
authors.initials: J
authors.lastname: Clardy
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.
authors.forename: Roberto
authors.identifier: 0000-0001-9548-1481
authors.initials: R
authors.lastname: Kolter
mesh_terms: D059001:Aquatic Organisms / Q000254:growth & development / Q000378:metabolism; D001422:Bacterial Adhesion; D002470:Cell Survival / Q000187:drug effects; D058087:Haptophyta / Q000378:metabolism / Q000382:microbiology* / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D041902:Rhodobacteraceae / Q000254:growth & development* / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D007210:Indoleacetic Acids; C030737:indoleacetic acid; D014364:Tryptophan
keywords: Emiliania huxleyi; Indole-3-acetic acid; Phaeobacter inhibens; Roseobacter group; ecology; programmed cell death; symbiosis