title: Distribution and diversity of Gallionella-like neutrophilic iron oxidizers in a tidal freshwater marsh.
abstract: Microbial iron oxidation is an integral part of the iron redox cycle in wetlands. Nonetheless, relatively little is known about the composition and ecology of iron-oxidizing communities in the soils and sediments of wetlands. In this study, sediment cores were collected across a freshwater tidal marsh in order to characterize the iron-oxidizing bacteria (FeOB) and to link their distributions to the geochemical properties of the sediments. We applied recently designed 16S rRNA primers targeting Gallionella-related FeOB by using a nested PCR-denaturing gradient gel electrophoresis (DGGE) approach combined with a novel quantitative PCR (qPCR) assay. Gallionella-related FeOB were detected in most of the samples. The diversity and abundance of the putative FeOB were generally higher in the upper 5 to 12 cm of sediment than in deeper sediment and higher in samples collected in April than in those collected in July and October. Oxygen supply by macrofauna appears to be a major force in controlling the spatial and temporal variations in FeOB communities. The higher abundance of Gallionella-related FeOB in April coincided with elevated concentrations of extractable Fe(III) in the sediments. Despite this coincidence, the distributions of FeOB did not exhibit a simple relationship to the redox zonation inferred from the geochemical depth profiles.
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB, Wageningen, Netherlands.
authors.forename: Juanjuan
authors.initials: J
authors.lastname: Wang
authors.forename: Susann
authors.initials: S
authors.lastname: Vollrath
authors.forename: Thilo
authors.initials: T
authors.lastname: Behrends
authors.forename: Paul L E
authors.initials: PL
authors.lastname: Bodelier
authors.forename: Gerard
authors.initials: G
authors.lastname: Muyzer
authors.forename: Marion
authors.initials: M
authors.lastname: Meima-Franke
authors.forename: Frank
authors.initials: F
authors.lastname: Den Oudsten
authors.forename: Philippe
authors.initials: P
authors.lastname: Van Cappellen
authors.forename: Hendrikus J
authors.initials: HJ
authors.lastname: Laanbroek
mesh_terms: D058645:Denaturing Gradient Gel Electrophoresis; D005618:Fresh Water / Q000382:microbiology*; D043372:Gallionellaceae / Q000145:classification* / Q000235:genetics*; D014644:Genetic Variation; D007501:Iron / Q000378:metabolism*; D054892:Metagenome; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D012621:Seasons; D053833:Wetlands
chemical_list: D007501:Iron