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.

Vertical distribution of Fe and Fe(III)-reducing bacteria in the sediments of Lake Donghu, China

“…The oxidation of organic matter with the reduction of Fe(III) is one of the most important redox reactions in anoxic environments (Hori et al 2010;Bongoua-Devisme et al 2013). Wang et al (2011) have confirmed that Fe(II)-oxidizing bacteria (FeOB) are ubiquitous in wetland sediments. Fe(III) oxides, such as poorly crystalline ferrihydrite produced by FeOB, were shown to be suitable for dissimilatory Fe(III)-reducing bacteria (FeRB) (Straub et al 1998;Blothe and Roden 2009).…”

Taxonomic and Functional Metagenomic Profiling of the Microbial Community in the Anoxic Sediment of a Sub-saline Shallow Lake (Laguna de Carrizo, Central Spain)

“…Among these sequences a large proportion affiliated with purple sulfur bacteria (Chromatiaceae; typical inhabitants of stagnant pools) and versatile heterotrophs such as Pseudomonas and Xanthomonas-like organisms, followed by sulfur-oxidizing phototrophs such as Lamprocystis, and one sequence distantly affiliated to methanotrophic organisms such as Methylocaldum(Figure S3). They were closely related to communities found in solar salterns[1,2], waters and sediments of freshwater reservoirs[55,83], wetland soils as well as karst and phreatic sinkholes and deepsea marine sediments[82]. Eleven clones (5.6%) affiliated to Alphaproteobacteria that were composed in essence of Sphingomonadaceae and Rhodobacteraceae-like organisms.Epsilonproteobacteria, constituting 2.1% of the Carrizo Lake bacterial clones, were affiliated to organisms distantly related to chemolithotrophic Sulfurovum litotrophicum and Sulfurimonas autotrophica, both involved in the redox sulfur cycle, and to uncultured bacteria from activated wastewater sludges.…”

“…Anoxic lake sediments from around the world, including those from saline and alkaline soda lakes [2,72], hypersaline lakes [73], athalassohaline lakes [28], shallow suboxic-to-anoxic freshwater ponds [5], sulfurous karstic lake [44], eutrophic lakes -including shallow [17,48,74,76], sulfur-rich minerotrophic peatlands [31], warm monomictic and meso-eutrophic lakes [68,69], freshwater tidal marshes [82], meromictic lakes [39,42], as well as metal miningimpacted lakes [8,13,19,59], have been studied, but most of this interest is centred on their phylogeny. Most of the communities were dominated by (un)culturable methane-producing archaea Methanomicrobiales, Methanobacteriaceae and Methanosarcinales and Crenarchaeota from uncultivable groups such as Miscellaneous Crenarchaeota group, Marine Group I, Marine Benthic Group B and C, Freshwater group, Group I3 and Rice Clusters IV and VI.…”

The influence of human settlement on the distribution and diversity of iron-oxidizing bacteria belonging to the Gallionellaceae in tropical streams

“…Due to the importance of Fe in biogeochemical redox cycles and its role as a potential microbial energy source, considerable research efforts have been invested in aiming to reveal the nature and numbers of ferrous iron Fe(II)-oxidizing bacteria (FeOB) in the environment (for example Ghiorse, 1984; Emerson and Weiss, 2004; Wang et al, 2009, 2011). …”