title: Isolation and characterization of a novel biomineral stalk-forming iron-oxidizing bacterium from a circumneutral groundwater seep.
abstract: The Fe-depositing microorganism Gallionella ferruginea was first described in 1836 based on its association with Fe-rich environments and its distinctive morphology. Since then, this morphology has been widely used to identify G. ferruginea. Researchers have isolated several Fe-oxidizing bacteria (FeOB) related to Gallionella; however, few isolates have produced organized extracellular biomineral structures, and of these, only one stalk former has a sequenced 16S rRNA gene, listed as G. ferruginea in the GenBank database. Here we report the isolation and characterization of a novel stalk-forming Fe-oxidizing bacterium, strain R-1, from a freshwater Fe seep. Despite a strong morphological similarity to G. ferruginea, this isolate has only 93.55% 16S rRNA gene sequence similarity with the previously determined sequence. R-1 only grows on Fe(II) substrates, at pH 5.6 to 7.0 and from 10°C to 35°C, with a doubling time of ∼15 h at pH 6.3 and 22°C. It is a Betaproteobacterium, most closely related to uncultured bacteria from microaerobic Fe(II)-rich groundwater springs. The most closely related isolates are Sideroxydans spp. (94.05-94.42% sequence similarity), FeOB that are not known to produce morphologically distinct minerals. To our knowledge, this is the first reported stalk-forming freshwater FeOB isolate distinct from Gallionella.
authors.affiliation: Department of Geological Sciences School of Marine Science and Policy, University of Delaware, Newark, DE 19716, USA.
authors.forename: Sean T
authors.initials: ST
authors.lastname: Krepski
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hanson
authors.forename: Clara S
authors.initials: CS
authors.lastname: Chan
mesh_terms: D020562:Betaproteobacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D005296:Ferrous Compounds / Q000378:metabolism*; D005618:Fresh Water / Q000382:microbiology; D043372:Gallionellaceae / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D060587:Groundwater / Q000382:microbiology*; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D005296:Ferrous Compounds; D012336:RNA, Ribosomal, 16S