title: Enhanced ferrihydrite dissolution by a unicellular, planktonic cyanobacterium: a biological contribution to particulate iron bioavailability.
abstract: Iron (Fe) bioavailability, as determined by its sources, sinks, solubility and speciation, places severe environmental constraints on microorganisms in aquatic environments. Cyanobacteria are a widespread group of aquatic, photosynthetic microorganisms with especially high iron requirements. While iron exists predominantly in particulate form, little is known about its bioavailability to cyanobacteria. Some cyanobacteria secrete iron solubilizing ligands called siderophores, yet many environmentally relevant strains do not have this ability. This work explores the bioavailability of amorphous synthetic Fe-oxides (ferrihydrite) to the non-siderophore producing, unicellular cyanobacterium, Synechocystis sp PCC 6803. Iron uptake assays with55ferrihydrite established dissolution as a critical prerequisite for iron transport. Dissolution assays with the iron binding ligand, desferrioxamine B, demonstrated that Synechocystis 6803 enhances ferrihydrite dissolution, exerting siderophore-independent biological influence on ferrihydrite bioavailability. Dissolution mechanisms were studied using a range of experimental conditions; both cell-particle physical proximity and cellular electron flow were shown to be important determinants of bio-dissolution by Synechocystis 6803. Finally, the effects of ferrihydrite stability on bio-dissolution rates and cell physiology were measured, integrating biological and chemical aspects of ferrihydrite bioavailability. Collectively, these findings demonstrate that Synechocystis 6803 actively dissolves ferrihydrite, highlighting a significant biological component to mineral phase iron bioavailability in aquatic environments.
authors: Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.|Interuniversity Institute for Marine Sciences in Eilat, POB 469, Eilat, 88103, Israel.
authors: Chana
authors: C
authors: Kranzler
authors: Interuniversity Institute for Marine Sciences in Eilat, POB 469, Eilat, 88103, Israel.|The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.
authors: Nivi
authors: N
authors: Kessler
authors: Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.
authors: Nir
authors: N
authors: Keren
authors: Interuniversity Institute for Marine Sciences in Eilat, POB 469, Eilat, 88103, Israel.|The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.
authors: Yeala
authors: Y
authors: Shaked
mesh_terms: D001682:Biological Availability; D001692:Biological Transport; D003676:Deferoxamine / Q000378:metabolism; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D008903:Minerals / Q000378:metabolism; D010933:Plankton / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism; D012995:Solubility; D046939:Synechocystis / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; D008903:Minerals; D017262:Siderophores; C092844:ferric oxyhydroxide; D007501:Iron; D003676:Deferoxamine