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Mixotrophic metabolism by natural communities of unicellular cyanobacteria in the western tropical South Pacific Ocean

Solange Duhamel; France Van Wambeke; Dominique Lefevre; Mar Benavides; Sophie Bonnet

Title:
Mixotrophic metabolism by natural communities of unicellular cyanobacteria in the western tropical South Pacific Ocean
Author(s):
Duhamel, Solange
Van Wambeke, France
Lefevre, Dominique
Benavides, Mar
Bonnet, Sophie
Date:
Type:
Articles
Department(s):
Lamont-Doherty Earth Observatory
Persistent URL:
Book/Journal Title:
Environmental Microbiology
Geographic Area:
South Pacific Ocean
Abstract:
Cyanobacteria are major contributors to ocean biogeochemical cycling. However, mixotrophic metabolism and the relative importance of inorganic and organic carbon assimilation within the most abundant cyanobacteria are still poorly understood. We explore the ability of Prochlorococcus and Synechococcus to assimilate organic molecules with variable C:N:P composition and its modulation by light availability and photosynthetic impairment. We used a combination of radiolabelled molecules incubations with flow cytometry cell sorting to separate picoplankton groups from the western tropical South Pacific Ocean. Prochlorococcus and Synechococcus assimilated glucose, leucine and ATP at all stations, but cell‐specific assimilation rates of N and P containing molecules were significantly higher than glucose. Incubations in the dark or with an inhibitor of photosystem II resulted in reduced assimilation rates. Light‐enhanced cell‐specific glucose uptake was generally higher for cyanobacteria (∼50%) than for the low nucleic acid fraction of bacterioplankton (LNA, ∼35%). Our results confirm previous findings, based mainly on cultures and genomic potentials, showing that Prochlorococcus and Synechococcus have a flexible mixotrophic metabolism, but demonstrate that natural populations remain primarily photoautotrophs. Our findings indicate that mixotrophy by marine cyanobacteria is more likely to be an adaptation to low inorganic nutrient availability rather than a facultative pathway for carbon acquisition.
Subject(s):
Biogeochemistry
Carbon cycle (Biogeochemistry)
Cyanobacteria
Publisher DOI:
https://doi.org/10.1111/1462-2920.14111
Item views
10
Metadata:
text | xml
Suggested Citation:
Solange Duhamel, France Van Wambeke, Dominique Lefevre, Mar Benavides, Sophie Bonnet, , Mixotrophic metabolism by natural communities of unicellular cyanobacteria in the western tropical South Pacific Ocean, Columbia University Academic Commons, .

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