Repeated Anaerobic Microbial Redox Cycling of Iron
| Autor: | Aaron J. Coby, Evgenya S. Shelobolina, Flynn W. Picardal, Eric E. Roden, Huifang Xu |
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| Rok vydání: | 2011 |
| Předmět: |
DNA
Bacterial Geologic Sediments Goethite Inorganic chemistry Microbial metabolism Fresh Water Acetates Dechloromonas DNA Ribosomal Ferric Compounds Applied Microbiology and Biotechnology Redox Denitrifying bacteria chemistry.chemical_compound Nitrate RNA Ribosomal 16S Cluster Analysis Ammonium Anaerobiosis Ferrous Compounds Phylogeny Nitrates Bacteria Ecology biology Chemistry Biodiversity Sequence Analysis DNA biology.organism_classification Geomicrobiology Quaternary Ammonium Compounds visual_art Environmental chemistry visual_art.visual_art_medium Oxidation-Reduction Food Science Biotechnology Geobacter |
| Zdroj: | Applied and Environmental Microbiology. 77:6036-6042 |
| ISSN: | 1098-5336 0099-2240 |
| DOI: | 10.1128/aem.00276-11 |
| Popis: | Some nitrate- and Fe(III)-reducing microorganisms are capable of oxidizing Fe(II) with nitrate as the electron acceptor. This enzymatic pathway may facilitate the development of anaerobic microbial communities that take advantage of the energy available during Fe-N redox oscillations. We examined this phenomenon in synthetic Fe(III) oxide (nanocrystalline goethite) suspensions inoculated with microflora from freshwater river floodplain sediments. Nitrate and acetate were added at alternate intervals in order to induce repeated cycles of microbial Fe(III) reduction and nitrate-dependent Fe(II) oxidation. Addition of nitrate to reduced, acetate-depleted suspensions resulted in rapid Fe(II) oxidation and accumulation of ammonium. High-resolution transmission electron microscopic analysis of material from Fe redox cycling reactors showed amorphous coatings on the goethite nanocrystals that were not observed in reactors operated under strictly nitrate- or Fe(III)-reducing conditions. Microbial communities associated with N and Fe redox metabolism were assessed using a combination of most-probable-number enumerations and 16S rRNA gene analysis. The nitrate-reducing and Fe(III)-reducing cultures were dominated by denitrifying Betaproteobacteria (e.g., Dechloromonas ) and Fe(III)-reducing Deltaproteobacteria ( Geobacter ), respectively; these same taxa were dominant in the Fe cycling cultures. The combined chemical and microbiological data suggest that both Geobacter and various Betaproteobacteria participated in nitrate-dependent Fe(II) oxidation in the cycling cultures. Microbially driven Fe-N redox cycling may have important consequences for both the fate of N and the abundance and reactivity of Fe(III) oxides in sediments. |
| Databáze: | OpenAIRE |
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