title: Elemental composition of natural populations of key microbial groups in Atlantic waters.
abstract: Intracellular carbon (C), nitrogen (N) and phosphorus (P) content of marine phytoplankton and bacterioplankton can vary according to cell requirements or physiological acclimation to growth under nutrient limited conditions. Although such variation in macronutrient content is well known for cultured organisms, there is a dearth of data from natural populations that reside under a range of environmental conditions. Here, we compare C, N and P content of Synechococcus, Prochlorococcus, low nucleic acid (LNA) content bacterioplankton and small plastidic protists inhabiting surface waters of the North and South subtropical gyres and the Equatorial Region of the Atlantic Ocean. While intracellular C:N ratios ranged between 3.5 and 6, i.e. below the Redfield ratio of 6.6, all the C:P and N:P ratios were up to 10 times higher than the corresponding Redfield ratio of 106 and 16, respectively, reaching and in some cases exceeding maximum values reported in the literature. Similar C:P or N:P ratios in areas with different concentrations of inorganic phosphorus suggests that this is not just a response to the prevailing environmental conditions but an indication of the extremely low P content of these oceanic microbes.
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Carolina
authors.initials: C
authors.lastname: Grob
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, Sydney, NSW, 2109, Australia.
authors.forename: Martin
authors.initials: M
authors.lastname: Ostrowski
authors.affiliation: National Oceanography Centre, Southampton, Hampshire, SO14 3ZH, UK.
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Holland
authors.affiliation: Department of Biology, University of Bergen, Bergen, Norway.
authors.forename: Mikal
authors.initials: M
authors.lastname: Heldal
authors.affiliation: Department of Biology, University of Bergen, Bergen, Norway.
authors.forename: Svein
authors.initials: S
authors.lastname: Norland
authors.affiliation: Laboratory for Electron Microscopy, University of Bergen, Bergen, Norway.
authors.forename: Egil S
authors.initials: ES
authors.lastname: Erichsen
authors.affiliation: Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: Claudia
authors.initials: C
authors.lastname: Blindauer
authors.affiliation: National Oceanography Centre, Southampton, Hampshire, SO14 3ZH, UK.
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Martin
authors.affiliation: National Oceanography Centre, Southampton, Hampshire, SO14 3ZH, UK.
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Zubkov
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Scanlan
mesh_terms: D059001:Aquatic Organisms / Q000378:metabolism; D001267:Atlantic Ocean; D002244:Carbon / Q000378:metabolism; D056890:Eukaryota / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D010839:Phytoplankton / Q000378:metabolism*; D048929:Prochlorococcus / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology*; D046940:Synechococcus / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen