Warming the phycosphere: differential effect of temperature on the use of diatom-derived carbon by two copiotrophic bacterial taxa.

Nestor Arandia-Gorostidi, Laura Alonso-Sáez, Hryhoriy Stryhanyuk, Hans H Richnow, Xose Anxelu G. Moran, Niculina Musat

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12 Scopus citations

Abstract

Heterotrophic bacteria associated with microphytoplankton, particularly those colonizing the phycosphere, are major players in the remineralization of algal-derived carbon. Ocean warming might impact DOC uptake by microphytoplankton-associated bacteria with unknown biogeochemical implications. Here, by incubating natural seawater samples at 3 different temperatures we analyzed the effect of experimental warming on the abundance and C and N uptake activity of Rhodobacteraceae and Flavobacteria, two bacterial groups typically associated with microphytoplankton. Using NanoSIMS single-cell analysis we quantified the temperature-sensitivity of these two taxonomic groups to the uptake of algal-derived DOC in the microphytoplankton-associated fraction with 13 C-bicarbonate and 15 N-leucine as tracers. We found that cell-specific 13 C uptake was similar for both groups (~0.42 fg C h-1  μm-3 ), but Rhodobacteraceae were more active in 15 N-leucine uptake. Due to the higher abundance of Flavobacteria associated with microphytoplankton, this group incorporated 4-fold more carbon than Rhodobacteraceae. Cell-specific 13 C uptake was influenced by temperature, but no significant differences were found for 15 N-leucine uptake. Our results show that the contribution of Flavobacteria and Rhodobacteraceae to C assimilation increased up to 6-fold and 2-fold, respectively, with an increase of 3°C above ambient temperature, suggesting that warming may differently affect the contribution of distinct copiotrophic bacterial taxa to carbon cycling. This article is protected by copyright. All rights reserved.
Original languageEnglish (US)
JournalEnvironmental microbiology
DOIs
StatePublished - Feb 25 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We are grateful to Basque Government for supporting N.A.G.’s Ph.D. fellowship the Spanish Ministry of Economy and Competitiveness (MINECO) for supporting L.A.S.’s Juan de la Cierva and Ramón y Cajal (RYC-2012-11404) fellowships and the COMITE project (CTM-2010–15840). We thank the Helmholtz Centre for Environmental Research and the Department of Isotope Biogeochemistry for providing the access to their infrastructure (ProVIS) and to M. G. for the EA-MS analysis. We are very thankful to all the staff of the R/V “José de Rioja” for their help during the sampling collection and L. Díaz and T.M. Huete-Stauffer for their help during the experiments.

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