Details

Autor(en) / Beteiligte

• Eichner, Meri J
• Klawonn, Isabell
• Wilson, Samuel T
• Littmann, Sten
• Whitehouse, Martin J
• Church, Matthew J
• Kuypers, Marcel MM
• Karl, David M
• Ploug, Helle

Titel

Chemical microenvironments and single-cell carbon and nitrogen uptake in field-collected colonies of Trichodesmium under different pCO2

Ist Teil von

• The ISME Journal, 2017-06, Vol.11 (6), p.1305-1317

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Gradients of oxygen (O 2 ) and pH, as well as small-scale fluxes of carbon (C), nitrogen (N) and O 2 were investigated under different partial pressures of carbon dioxide ( p CO 2 ) in field-collected colonies of the marine dinitrogen (N 2 )-fixing cyanobacterium Trichodesmium . Microsensor measurements indicated that cells within colonies experienced large fluctuations in O 2 , pH and CO 2 concentrations over a day–night cycle. O 2 concentrations varied with light intensity and time of day, yet colonies exposed to light were supersaturated with O 2 (up to ~200%) throughout the light period and anoxia was not detected. Alternating between light and dark conditions caused a variation in pH levels by on average 0.5 units (equivalent to 15 nmol l −1 proton concentration). Single-cell analyses of C and N assimilation using secondary ion mass spectrometry (SIMS; large geometry SIMS and nanoscale SIMS) revealed high variability in metabolic activity of single cells and trichomes of Trichodesmium, and indicated transfer of C and N to colony-associated non-photosynthetic bacteria. Neither O 2 fluxes nor C fixation by Trichodesmium were significantly influenced by short-term incubations under different p CO 2 levels, whereas N 2 fixation increased with increasing p CO 2 . The large range of metabolic rates observed at the single-cell level may reflect a response by colony-forming microbial populations to highly variable microenvironments.