Response of marine bacterioplankton pH homeostasis gene expression to elevated CO2

Carina Bunse, Daniel Lundin, Christofer M.G. Karlsson, Neelam Akram, Maria Vila-Costa, Joakim Palovaara, Lovisa Svensson, Karin Holmfeldt, José M. González, Eva Calvo, Carles Pelejero, Cèlia Marrasé, Mark Dopson, Josep M. Gasol, Jarone Pinhassi

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38 Citations (Scopus)

Abstract

Human-induced ocean acidification impacts marine life. Marine bacteria are major drivers of biogeochemical nutrient cycles and energy fluxes; hence, understanding their performance under projected climate change scenarios is crucial for assessing ecosystem functioning. Whereas genetic and physiological responses of phytoplankton to ocean acidification are being disentangled, corresponding functional responses of bacterioplankton to pH reduction from elevated CO2 are essentially unknown. Here we show, from metatranscriptome analyses of a phytoplankton bloom mesocosm experiment, that marine bacteria responded to lowered pH by enhancing the expression of genes encoding proton pumps, such as respiration complexes, proteorhodopsin and membrane transporters. Moreover, taxonomic transcript analysis showed that distinct bacterial groups expressed different pH homeostasis genes in response to elevated CO2. These responses were substantial for numerous pH homeostasis genes under low-chlorophyll conditions (chlorophyll a <2.5 μg l-1); however, the changes in gene expression under high-chlorophyll conditions (chlorophyll a >20 μg l-1) were low. Given that proton expulsion through pH homeostasis mechanisms is energetically costly, these findings suggest that bacterioplankton adaptation to ocean acidification could have long-term effects on the economy of ocean ecosystems.

Original languageEnglish
Pages (from-to)483-487
Number of pages5
JournalNature Climate Change
Volume6
Issue number5
DOIs
Publication statusPublished - 27 Apr 2016

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    Bunse, C., Lundin, D., Karlsson, C. M. G., Akram, N., Vila-Costa, M., Palovaara, J., Svensson, L., Holmfeldt, K., González, J. M., Calvo, E., Pelejero, C., Marrasé, C., Dopson, M., Gasol, J. M., & Pinhassi, J. (2016). Response of marine bacterioplankton pH homeostasis gene expression to elevated CO2. Nature Climate Change, 6(5), 483-487. https://doi.org/10.1038/nclimate2914