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

Lookup NU author(s): Professor Sam Wilson

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Abstract

© 2017 International Society for Microbial Ecology All rights reserved. Gradients of oxygen (O2) and pH, as well as small-scale fluxes of carbon (C), nitrogen (N) and O2 were investigated under different partial pressures of carbon dioxide (pCO2) in field-collected colonies of the marine dinitrogen (N 2)-fixing cyanobacterium Trichodesmium. Microsensor measurements indicated that cells within colonies experienced large fluctuations in O2, pH and CO2 concentrations over a day-night cycle. O2 concentrations varied with light intensity and time of day, yet colonies exposed to light were supersaturated with O2 (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 O2 fluxes nor C fixation by Trichodesmium were significantly influenced by short-term incubations under different pCO2 levels, whereas N 2 fixation increased with increasing pCO2. 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.

Publication metadata

Author(s): Eichner MJ, Klawonn I, Wilson ST, Littmann S, Whitehouse MJ, Church MJ, Kuypers MMM, Karl DM, Ploug H

Publication type: Article

Publication status: Published

Journal: ISME Journal

Year: 2017

Volume: 11

Issue: 6

Pages: 1305-1317

Print publication date: 01/06/2017

Online publication date: 11/04/2017

Acceptance date: 09/01/2017

Date deposited: 16/12/2021

ISSN (print): 1751-7362

ISSN (electronic): 1751-7370

Publisher: Springer Nature

URL: https://doi.org/10.1038/ismej.2017.15

DOI: 10.1038/ismej.2017.15

PubMed id: 28398346

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