Efficient CO2 fixation by surface Prochlorococcus in the Atlantic Ocean.
Nearly half of the Earth's surface is covered by the ocean populated by the most abundant photosynthetic organisms on the planet--Prochlorococcus cyanobacteria. However, in the oligotrophic open ocean, the majority of their cells in the top half of the photic layer have levels of photosynthetic pigmentation barely detectable by flow cytometry, suggesting low efficiency of CO2 fixation compared with other phytoplankton living in the same waters. To test the latter assumption, CO2 fixation rates of flow cytometrically sorted (14)C-labelled phytoplankton cells were directly compared in surface waters of the open Atlantic Ocean (30°S to 30°N). CO2 fixation rates of Prochlorococcus are at least 1.5-2.0 times higher than CO2 fixation rates of the smallest plastidic protists and Synechococcus cyanobacteria when normalised to photosynthetic pigmentation assessed using cellular red autofluorescence. Therefore, our data indicate that in oligotrophic oceanic surface waters, pigment minimisation allows Prochlorococcus cells to harvest plentiful sunlight more effectively than other phytoplankton.
Ocean Biogeochemistry and Ecosystems Research Group, National Oceanography Centre, Southampton, UK.
Manuela
0000000247742787
M
Hartmann
Ocean Biogeochemistry and Ecosystems Research Group, National Oceanography Centre, Southampton, UK.
Paola
P
Gomez-Pereira
School of Life Sciences, University of Warwick, Coventry, UK.
Carolina
C
Grob
School of Life Sciences, University of Warwick, Coventry, UK.
Martin
M
Ostrowski
School of Life Sciences, University of Warwick, Coventry, UK.
David J
DJ
Scanlan
Ocean Biogeochemistry and Ecosystems Research Group, National Oceanography Centre, Southampton, UK.
Mikhail V
MV
Zubkov
D001267:Atlantic Ocean; D057486:Carbon Cycle; D010788:Photosynthesis; D010839:Phytoplankton / Q000378:metabolism; D048929:Prochlorococcus / Q000302:isolation & purification / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology*; D046940:Synechococcus / Q000378:metabolism