Investigation on the iron-uptake by natural biofilms

• Published in: Water research (Oxford) 2014-03, Vol.50, p.212-220
• Main Authors: Julien, C., Laurent, E., Legube, B., Thomassin, J.-H., Mondamert, L., Labanowski, J.
• Format: Article
• Language: English
• Subjects: Bacteria - metabolism; Biofilm; Biofilms; Calcium - analysis; Catalysis; Chemical Sciences; Earth sciences; Earth, ocean, space; Exact sciences and technology; Hydrology; Hydrology. Hydrogeology; Iron; Iron - metabolism; Ligands; Manganese - analysis; Microscopy, Electron, Scanning; Natural water; Silicon - analysis; Solutions; Uptake
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2013.12.008

Biofilms are natural communities of microorganisms living in aquatic ecosystems which play an important role in the biogeochemistry of many inorganic elements, including iron. The present work aimed to study the uptake of iron by natural river biofilms (produced in the laboratory) and to examine the relationships between biofilms and iron in water. For that, biofilms were formed from natural water samples collected at different times of the year. Total content and global localization of iron were determined by a combination of chemical analyses and microscopy, which indicated that iron was systematically distributed throughout the biofilm matrix. Depending on the level of iron uptake, iron was diffuse or present as hot spots, was primarily localized to the fraction ascribed to OM compounds (45–60%) or the residual fraction (∼14–40%). Additional experiments were conducted using iron–organic complexes with different affinities (log K) to study iron uptake according to the speciation. These experiments suggested the association between iron and organic ligands (i.e. depending on the affinity constant) influenced the uptake of iron, but did not control the biofilm affinity for iron, which appeared to be controlled by chemical-kinetic laws. •Different levels of iron-uptake may be observed in natural biofilms.•Iron-uptake is influenced by chemical-kinetic laws.•Iron-uptake is neither a pure biological phenomenon nor a thermodynamical phenomenon.•Iron-uptake increases with the presence of available iron-ligand complexes.