title: Survey of the green picoalga Bathycoccus genomes in the global ocean.
abstract: Bathycoccus is a cosmopolitan green micro-alga belonging to the Mamiellophyceae, a class of picophytoplankton that contains important contributors to oceanic primary production. A single species of Bathycoccus has been described while the existence of two ecotypes has been proposed based on metagenomic data. A genome is available for one strain corresponding to the described phenotype. We report a second genome assembly obtained by a single cell genomics approach corresponding to the second ecotype. The two Bathycoccus genomes are divergent enough to be unambiguously distinguishable in whole DNA metagenomic data although they possess identical sequence of the 18S rRNA gene including in the V9 region. Analysis of 122 global ocean whole DNA metagenome samples from the Tara-Oceans expedition reveals that populations of Bathycoccus that were previously identified by 18S rRNA V9 metabarcodes are only composed of these two genomes. Bathycoccus is relatively abundant and widely distributed in nutrient rich waters. The two genomes rarely co-occur and occupy distinct oceanic niches in particular with respect to depth. Metatranscriptomic data provide evidence for gain or loss of highly expressed genes in some samples, suggesting that the gene repertoire is modulated by environmental conditions.
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Vannier
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Jade
authors.initials: J
authors.lastname: Leconte
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Seeleuthner
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Mondy
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Pelletier
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Aury
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR7144, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Colomban
authors.initials: C
authors.lastname: de Vargas
authors.affiliation: National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Sieracki
authors.affiliation: Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Iudicone
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR7144, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vaulot
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Wincker
authors.affiliation: CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry, France.|CNRS, UMR 8030, CP5706 Evry, France.|Université d'Evry, UMR 8030, CP5706 Evry, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Jaillon
mesh_terms: D000460:Chlorophyta / Q000235:genetics*; D060146:Ecotype; D023281:Genomics / Q000379:methods; D054892:Metagenome / Q000235:genetics*; D056186:Metagenomics / Q000379:methods; D058086:Microalgae / Q000235:genetics*; D009792:Oceans and Seas; D010802:Phylogeny; D010839:Phytoplankton / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater; D011795:Surveys and Questionnaires
chemical_list: D012337:RNA, Ribosomal, 18S