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Foto de: Bryant lab, Penn State
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Recientemente se ha publicado un artículo
dentro del proyecto EACFe por G. Samperio-Ramos, J. M. Santana-Casiano y M.
González-Dávila, en la revista Journal of
Oceanography.
En esta publicación, los autores muestran la
producción de compuestos orgánicos en diferentes condiciones de Fe y de
crecimiento de las cianobacterias. En concreto, se midieron el contenido en
carbono orgánico disuelto (DOC), hidroxamatos y fenoles.
La adición de Fe provoca que aumente la
concentración de DOC, mientras que la concentración de hidroxamatos se inhibe
en estas condiciones de alta concentración de Fe. Por otro lado, Synechococcus PCC 7002 excreta menos
compuestos polifenólicos a altos niveles de Fe.
A continuación puede leer el resumen completo
(en inglés).
Variability in the
production of organic ligands, by Synechococcus PCC 7002, under
different iron scenarios
Abstract
Several Fe-uptake mechanisms
suggest the importance of the presence of certain organic ligands in
phytoplankton exudates. Here, it has been studied how Synechococcus (strain PCC
7002) acclimates to Fe-bioavailability, comparing the growth and organic
exudation under two different Fe regimes. These cyanobacteria were incubated in
UV-treated seawater supplemented only with major nutrients and two different
iron scenarios (Low-Fe and High-Fe), without chelating agents, in order to
analyze the organic ligands production. The levels of dissolved organic carbon
(DOC) and two natural ligands (hydroxamic and phenolic moieties) were
monitored. The responses in the organic extracellular release rates (ER),
normalized per cell, were statistically analyzed considering Fe scenarios and
different development stages. Growth of Synechococcus was
significantly slower under Low-Fe treatment, suggesting that these cultures
were iron limited compared to those flourished with higher levels of iron in
the medium. Although the concentration of DOC increased to
127.13 ± 8.38 and 150.51 ± 8.59 μmol C L−1 under
Low-Fe and High-Fe conditions, respectively, no-significant variations were
found in the DOCER, among growth phases and iron bioavailability
scenarios. Under High-Fe conditions, the production of hydroxamic ligands was
inhibited, while the extracellular release rate of phenolic compounds
decreased, regarding to Low-Fe conditions. Growth phases of Synechococcus also modified
the extracellular release rates both of hydroxamic and phenolic moieties. The
present study, therefore, demonstrates that iron availability and growth stages
might be key parameters in regulating the release performance of extracellular
Fe-specific organic ligands by cyanobacteria.
