engleski

Flexible Selection of Iron Sources by Marine Microbial Consortia Related to Temperature

Effects of various soluble iron(III) complexes: iron (III)chloride and nitrate salts, iron(III) - ethylene diamine tetraacetate complex (EDTA ; synthetic ligand), and succinate, citrate and malate complexes (naturally occurring low molecular weight ligands) and temperature, on the growth and cell volume of a diatom Skeletonema marinoi Sarno and Zingone in iron limited laboratory conditions, were studied. Temperatures were ranging from 18 to 25°C. Phytoplankton growth and cell volume responded differently to various iron(III) complexes. The growth of S. marinoi was found to be significantly influenced by temperature in treatments with iron(III)-malate and iron(III)nitrate. In treatments with iron(III)-EDTA, - succinate and -citrate significant correlation between growth and temperature was not found indicating that in these three cases the influence of iron(III) speciation was the predominant limiting factor, especially in treatments with iron(III)- succinate and -citrate. S. marinoi growth curves, cell volumes and log cell volumes were analyzed on temperature with a second order polynomial regression analysis. Results denote significant correlation of cell volume and temperature in treatments with iron(III)-EDTA, iron(III)-citrate and iron(III)- malate. Our results indicate that constant extracellular release of metabolites (i.e. malate) by eucariotes and tricarboxylic acid cycle (TCA cycle, the Krebs cycle) metabolites excreted by prokaryotes can play a significant role in the pathways of iron in the ocean as an important iron solubilization mechanism.

temperature; iron(III) complexes; marine diatoms; iron transport; microbial loop; phytoplankton; biomass

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